The following links are to information and resources such as institutions and organizations, databases or specialized links pages, articles, referenced data or well-written handbooks. All of the web sites noted here have been reviewed by SRC and selected for professional quality, relevance and content. Readers are invited to suggest links for any of the categories. Links are added at SRC's discretion and without obligation. Link exchanges with appropriate sites are welcomed.

Sensors and Instrumentation
(see also smart materials)

>>>>BACKGROUND SOURCES

ISA The Instrumentation, Systems and Automation Society. "Connecting people and ideas in automation and control." See also, ISA Sensors guide short descriptions of some key technologies for flow, level, position, pressure and temperature and ISA Intech News

Refereed Journals:
Sensors and Actuators A: Physical an Elsevier journal "devoted to disseminating information on all aspects of research and development of solid-state devices for transducing physical signals. " This is part of the Elsevier site which provides online electronic services, much of which require a subscription. However there is a lot of useful information for the non-subscriber, such as a searchable table of contents for 1,100 or so Elsevier Journals which occasionally links to a journal with searchable abstracts, as for example, JASM (The Journal of the American Society for Mass Spectrometry.)
IEEE Sensors - The IEEE Sensors Journal; a collection of sensors tutorials; sensors related conference announcements. <LS>
Sensors journal - is a peer-refereed scientific journal, published online monthly.
Review of Scientific Instruments - AIP Pub.
Measurement Science and Technology - IOP Pub.

Trade journals:
Sensors Magazine a very informative site, including full text access to articles - articles archive - free subscription to the magazine if you work in the field of sensors.
Other trade journals: Control Engineering - part of the manufacturing.net library of magazines
Spectroscopy Magazine - this site includes spectroscopy tutorials mostly focused on ICP-MS, links and more.

Some other broad or basic background information sites:
Sensors Web Portal - an online library of reference articles relating to a wide range of different physical and chemical sensors. Courtesy IFSA. <LS>
Encyclopedia of Analytical Instrumentation - explanations of a wide range of analytical techniques under 17 different titles including electrochemistry and spectroscopy (e.g. about 20 technologies), courtesy of Brian Tissue, Virginia Tech.
The Basics of NMR - an excellent hypertextbook on the basics of NMR spectroscopy written by Joseph. P. Hornak, Ph.D., (freely accessible online, well written and organized including embedded graphics).
Short course on sensorics - this site outlines the basics of a broad range of sensing principles, physical and chemical effects, related specialized structures referenced to measurement parameters and applications and covering many different types of sensor, such as electrochemical, biosensors, Hall effect, acoustic wave, ISFET's and so on. Excellent animated graphics with brief text explanations. Suitable for a quick review or if you are completely new to sensors. [BTW: origin of the term "sensorics' is unknown and not in common use.] Dept. Electronics Techn.,Budapest University of Technology & Economics.
Advanced Sensors Database for Food Manufacturing - a site provided by the Center for Food Manufacturing at Penn State. Describes specific sensors technologies, namely X ray, machine vision, NMR, fluorescence, ultrasound and impedance which are variously used to measure defects, color, internal properties, texture, moisture, firmness, chemical composition, oil content and foreign materials along with a flow sensors database describing the various flow sensing technologies used in the food industry.
Omega online technical reference - a large site including a series of short articles related to sensing pressure, strain, force, liquid level and flow (including principles of valves), pH, conductivity, turbidity, data acquisition and access to Omega's Transactions in Measurement and Control.
Vibration sensor selection guide and information on conductivity measurements of liquids - Cole Palmer Technical Library.
Microphone Handbook - PCB Piezotronics Inc. make a range of piezoelectric based sensors, including dynamic pressure, vibration, load, torque, acceleration, shock and acoustics and provide some information about the technologies.
The MEMS and Nanotechnology Clearinghouse
Sensorland.com - On-Line information for engineers to learn about and source all types of Sensors and Measurement Equipment. <SRC LE>

A few possibly less familiar example technologies:

Attitude sensors for satellites - descriptions of a number of different types by TNO.
Touch Technologies - touch screen technologies for use with computer monitors, terminals and flat panel displays - Elo Touch.
SenSable Technologies - haptic systems
Cyberlaboratory - a well designed site provided by Mettler-Toledo describing the basics of density measurement and refractometry, the different types of instrumentation and a collection of applications articles in pdf format, including beer and wine analysis.
Keyence - free downloads of application guides including machine vision, thickness measurement, eccentricity and vibration measurements.
Fingerprint sensor chip technology - thermal using pyroelectrics, Atmel
Laser based particle size analysis - includes brief explanations of Fraunhofer and Mie theory. CILAS.
Fundamentals of Ultrasonic Imaging and Flaw Detection and Ultrasonic Non-Destructive Testing - Advanced Concepts and Applications - tutorials provided by National Instruments.
Data acquisition technical notes and tutorials - courtesy of Biodata Ltd. <LS>

>>>>ACCELEROMETERS
units of acceleration: 1g = standard value of acceleration due to earth's gravity; 1Gal=1cm/s.s, (in honour of Galileo). Not to be confused with gram and gallon.

Accelerometers are used to measure acceleration, vibration, shock, tilt and inclination in a variety of industrial systems applications and consumer products. Higher performance versions are used in inertial navigation systems. Newton's Law, F=ma, dominates the principle of operation. A test or proof mass is typically built-in which responds to the local acceleration. As a rough guide, the larger the device, and hence test mass, the larger is the resulting inertial force due to an acceleration, which thus gives rise to greater measurement sensitivity. Since mass scales as the cube of linear dimension, ultimate sensitivities scale dramatically with sensor size. Low cost MEMS devices can have sensitivities in the region of mg's (milli gees). The larger instrument grade non-MEMS discrete devices used for instance in navigation systems may have sensitivities in the region of microg's, while the much larger gravimetric instruments can have sensitivities roughly 1000 times more than that or in the region of 1 micro Gal.

MEMS overview - this page illustrates early work on the development of a MEMS accelerometer - Sandia.
Heatbeat Sensor - a system called SecureCar for recognizing and monitoring occupancy based on faint heartbeat sounds and which uses two ultra sensitive, micro-accelerometers. Developed by Ford Motor Company.
Optical Accelerometer based on Fabry-Perot Interferometry - research to develop a navigation grade device - J.Eklund, Univ.Cal., Irvine.

Commercial examples:

iMEMS Accelerometers - small, low cost, used in automotive air bag systems as well as for other industrial and consumer device applications. Analog Devices.
MEMSIC - MEMs based technology based on a proprietary natural gas convection principle instead of the typical solid proof mass. Acceleration is a factor determining natural convective heat transfer coefficients.
Jewell Instruments - range of sensitivities.
Honeywell accelerometers - for navigation systems, industrial control, measurement and energy applications.
Honeywell Sensotec accelerometers - includes brief explanations of piezoelectric and piezoresistive types.
Optical accelerometer - primary application stator winding vibration measurement in electric generators and motors (100mV/g) - FOA.
Fiber optical accelerometers - light is reflected off a vibration sensitive flat spring causing intensity modulation - single and dual axis versions - multiple applications (100mV/g) - Optoacoustics.

Subtopic: Gravity sensing
Instruments that measure the local gravitational field are extremely sensitive accelerometers and find application in geosurveys and exploration. Different technologies are used compared with typical industrial accelerometers. In this application, the instruments are called gravimeters or gravitometers, terms which unfortunately are also shared by some completely different types of sensor. The typical unit of measure is the Gal, where 1 Gal = 1cm/s.s.

Mass and Spring Gravity Measurements - Univ. Melbourne.
Gravimetry: Absolute gravity - This site describes example instruments and includes an online version of "A Free-Fall Determination of the Newtonian Constant of Gravity" by J. P. Schwarz, et al, published in Science, 282, 2230-2234, 1998. Also known as big G, this constant indicates the strength of the gravitational interaction. The paper describes the experimental apparatus and technique devised, results and analysis.. Geosciences Research Division, National Geodetic Survey.
Micro g LaCoste - commercial gravimeters.
LIGO - Laser Interferometer Gravitational Wave Observatory. This is essentially a very large and sensitive gravimeter and it was built to allow various cosmological observations for research purposes - Caltech and MIT.


>>>>DISTRIBUTED SENSOR NETWORKS

ACM Transactions on Sensors Networks - Journal.
The NASA/JPL Sensor Webs Project - Development of an advanced system for communicating data to and from distributed sensing and instrumentation platforms (or pods), applied to environmental monitoring.
Wireless Sensor Research at NIST - Research activities include the fundamental physics that are involved in transmitting signals, new application areas for wireless sensors, developing efficient means of transmitting messages through networks, and developing standards to ease their use.
SensorWare Systems - a company which markets Sensor Web systems, (originally developed at NASA). See for example, real time streaming data graphs from a SensorWare Systems installation at Huntington Botanical Gardens.
Wireless Sensors Networks - Crossbow Technology.
Wireless Sensor Networks Blog
Dust Networks - embedded wireless sensor networking for monitoring and control. Informative site. See for example a white paper, Technical Overview of Time Synchronized Mesh Protocol (TSMP).
Sensors networks - an information rich site courtesy of A. Bharathidasan, which includes links to research activities, applications and literature, including a review of the current status and issues concerning sensor networks, (.pdf) by A. Bharathidasan, V. A. S. Ponduru; Department of Computer Science,University of California, Davis, CA.
Wireless Sensor Networks for Medical Care- a project by Division Engineering and Applied Sciences, Harvard Univ.
Wireless Sensor Networks- 18 page article by F.L.Lewis, Advanced Controls, Sensors, and MEMS Group, Automation and Robotics Institute, Univ. Tex., Arlington.
Scaleable Wireless Web-enabled Sensor Networks- A 38 page pdf white paper from MicroStrain.
E-Textiles at Virginia Tech - e-textiles / intelligent fabrics is a developing area and represent another example of distributed sensor network.
Smart Sensors to Network the World - article by D.E.Culler, H.Mulder, Sci.Am., 2004.
Instrumenting the World - a short article, Intel.

Subtopic: Sensor data fusion
Data fusion concerns how to make sense of the data from multiple sensors in an environment so as to be able to discern specific events rapidly for alarms, extraction of information or control signal purposes and has been growing in importance over the course of the past decade. An early successful example of data fusion was the use of neural networks to process the data from an array of MOS sensors thus giving rise to electronic nose technology. Today distributed sensor networks are rapidly growing in complexity and diversity of applications. Hence, data fusion is emerging as a distinct area of research. It encompasses signal processing methodologies such as neural networks, fuzzy logic and Kalman filtering and fusion techniques are guided by application objectives and network structure, (topologies such as centralized, hierarchical, mesh, and sensor data types, etc.).

Information Processing in Sensor Networks - annual conference series hosted by Virginia Tech.
Data fusion research related to image sources - The Sensor Networks Group, Dept. E.E.Eng., Univ. Melbourne.
Bayesian Approaches to Multi-Sensor Data Fusion - O. Punska, MPhil Thesis, Univ. Cambridge, UK, 1999. (.pdf)
Ice regime of lakes and inland seas from multi-sensor data fusion - natural and anthropogenic factors - an abstract on work concerning the fusion of multi-sensor satellite data, A. V. Kouraev et al, Geophysical Research Abstracts, Vol. 7, 00932, 2005. (pdf)
Fuzzy Systems - a short tutorial about fuzzy logic provided by Quadralay Corporation.

Subtopic: Distributed computing

Information on recent distributed computing research for sensor networks at Dept Computer Science & Engineering, Washington University, St.Louis

>>>>ELLIPSOMETRY
Ellipsometry is an optical technique devoted to the analysis of surfaces and films.

Spectroscopic ellipsometry - SOPRA.
Beaglehole Instruments
Spectroscopic ellipsometry at the University of Michigan - research by Dr. F. Terry in the characterization of semiconductor fabrication processes. <LS>

>>>>FIBER OPTIC SENSORS (see also Smart Materials, Magnetic Field Sensors, Accelerometers and Biomedical sensors)
Fiber optic sensors can be divided into two categories: 1. extrinsic types comprising a sensing tip and the fiber relays light for activating or interrogating the sensor and then relays optical information back from the tip; 2. intrinsic types where the fiber itself is the sensor, which, for example, may undergo a length change for strain measurements, etc.

Fiber optic sensors - a short, well-written tutorial, courtesy of Canadian Instrumentation & Research Ltd.
Understanding Fiber Optic Gyroscopes - slide presentation, Physics Dept., METU.
Walt Group at Tufts - research into optical sensor arrays for chemical sensing, The Walt Group, Tufts University.

Commercial Examples:

FISO Technologies, Inc. - Fiber optic sensors for temperature, pressure, strain displacement, refractive index, force and load.
Fiber optic displacement transducer - MTI Instruments, Inc.
Fiber optic electric field and voltage sensors - SRICO.
Fiber optic temperature sensor - based on GaAs, (i.e. extrinsic), however you have to dig deep into the site to find it!, GetSpec.
Distributed pressure, temperature and strain - intrinsic types, various measurement systems utilizing OTDR (optical time domain reflectometry), Sensornet.

>>>>FLOW SENSORS
Flow is one of the more difficult measurements. This is due to the diversity of media types and conditions, application environments and performance requirements, along with the fact that flow is not a scalar quantity such as pressure or temperature. The bulk of commercial fluid flow sensors are designed for metering flows of liquids and gases in closed-conduits, (pipes and tubes), and these devices encompass about a dozen different distinct technologies. Applications for free field measurements encompass oceanographic measurements, meteorology and fluid dynamics R&D and come under the names of anemometers and current meters. They may be mechanical, thermal, optical or ultrasonic. Open-channel liquids flow measurements entail other technologies which find application in rivers, streams and irrigation channels. There are also a myriad of specialized devices used in specific fields, for example in biomedical applications, (see biomedical section), and for instance in the oil industry where the flow may be a mixture of oil and water or multiphase. Additionally, some flow sensors boast multiparameter capabilities and can provide additional information on the flow and state of the flow media. For instance, coriolis meters also provide density information, ultrasonic can also provide velocity of sound information and other meters incorporate additional sensors for temperature, on-board processing for derived parameters and so on.

The Flow Control Network The home site of Flow Control Magazine provides a wide range of fluids handling (measurement and control) information, links and a searchable database.
Flow Meter Directory - An internet resource for information on suppliers and manufacturers of Coriolis Mass Electromagnetic, Medical, Multiphase, Open Channel, Orifice plate, Positive Displacement, Target, Turbine, Thermal Mass, Ultrasonic, Variable Area, Venturi, Vortex shedding flowmeters. Also accepts submission of technical articles from students and industry professionals on flow measurement related topics. <SRC LE>

Closed-conduit:

An Introduction to Closed-Conduit Flow Sensing - includes a review of 8 different technologies. (Slide format; 3.0 Mb) Provided by Sensors Research Consulting, Inc.
Turbine flowmeters - a technical review article including theory of operation and applications - axial turbines (single and dual rotor) insertion axial turbines, propeller meters, spirometers and multi-jet turbines. Provided by Sensors Research Consulting, Inc.
Handbook of multiphase flow metering - Norwegian Society for Oil and Gas Measurement & Tekna; (115 pages, large pdf file)

Free field:

Dantec Dynamics - products include laser Doppler anemometry (LDA), particle image velocimetry (PIV), laser-induced fluorescence (LIF) and hot wire (CTA) anemometer systems. Applications include research and diagnostics into flow, turbulence, microfluidics, spray atomisation and combustion processes. The site provides descriptions of the basic measurement principles of the various techniques.
Ultrasonic - 2D and 3D meters for a range of applications including ocean, waterway, research and hydrology. SonTek.
Cup anemometer - three-cup rotor assembly - research and commercial applications in meteorology and wind energy - WindSensors, Denmark.

Open channel:
There are two basic methods. One is to measure the head of liquid upstream of a flume or weir in the channel. Common types used include rectangular and V-notch weirs, Parshall and Palmer Bowlus flumes. The other method, which is more practical for streams and rivers, is to measure the flow velocity at specific locations (profiling) and from there calculate the net flow.

Open Channel Velocity Profiling - tutorial. Also white paper on a system for open channel flow measurement which uses a radar-based surface velocity measurement along with auxiliary ultrasonic and electromagnetic sensors. Marsh-McBirney, Inc.
Weirs and flumes - Rickly Hydrological Company.
Open channel flow meter - ultrasonic measurement of liquid surface height for use with weirs and flumes. Eesiflo

>>>MACHINE OLFACTION (a.k.a. electronic nose; gas sensor array devices)
Typically comprising an array of discrete gas sensors, some of which may be semiconductor types, which have overlapping sensitivities and which may be linked into a neural network which is trained to recognize specific odors or compounds.

Electronic nose and olfactory article in R&D Magazine - April 1998.
NOSE II Network Archive

Commercial Examples:

Electronic Nose & electronic tongue odor & taste control - Alpha M.O.S.
Cogniscent Inc. - fluorescent optically active sensor array devices trained to recognize a range of trace level gases and odors for industrial and security applications.

>>>>MAGNETIC FIELD SENSORS
Field measurement types include: induction (search) coils, fluxgate, fiber optic, SQUID, Hall effect, magnetoresistive, proton precession, and optically pumped. Switches and position sensors additionally include reed switches and Wiegand sensors.

Some background and applications:

Magnetometer used in the Advanced Composition Explorer (ACE) spacecraft - triaxial fluxgate type for the measurement of the local interplanetary magnetic field.
Geophysical Institute Magnetometer Array - University of Alaska
Introduction to Magnetochemistry - David Young.
Brief descriptions of different types of magnetometers - by RS Operations, LLC.
Electronic signal processing in an optical-fiber based magnetometer - relates to an extrinsic Fabry-Perot Interferometric type, Masters Thesis, J, Ranade, 1997, Virginia Tech. (.pdf)
Fiber optic magnetic sensors for underwater traffic control- Naval Research Lab.
Position sensing systems - multiple applications - Ascension Technology Corporation.
The Giant Magnetoresistive Head - IBM Research (includes animations)
GMR spintronics magnetic sensors - For example see Eddy-Current testing with GMR Magnetic Sensor Arrays, C. H. Smith, et al. (pdf), NVE, Nonvolatile Electronics, Inc.
Compass chip, spinning-current Hall plate ASIC and application as an electronic compass. Xensor Integration, Delft, Netherlands.
"Novel magnetic force microscope using non-optical piezoelectric quartz tuning fork detection design", abstract of a paper by M. Todorovic and S. Schultz, UCSD.

Commercial Examples:

Low power Hall effect switch - online article, Allegro Microsystems, Inc.
Reed and Hall effect position and movement sensors - Hamlin Electronics.
Magnetostrictive sensors - linear position and liquid level, MTS Systems Corp.
Magnetic sensors applications from Honeywell - A range of applications including vehicle detection, position sensing, magnetometry, compassing, telematics, GPS Navigation, current sensing and Navigation Systems.
Bartington Instruments Ltd - fluxgate and induction types.
GEM Systems Inc. - Overhauser proton precession and optically pumped potassium magnetometers.
Applied Physics Systems - DC SQUID and fluxgate magnetometers.
SQUID AG - a SQUID magnetometer system designed for use in cardiology (magnetocardiology).
Wiegand effect sensors - generate output pulses when alternating magnetic fields pass near the sensor - HID Corporation.

>>>>MAGNETOTELLURIC SENSING
Magnetotelluric (MT) sensing is a technique used for investigating the structure and composition of the earth's lithosphere (surface down to about 10 or even 100 km) for geophysics research and oil, gas, water or mineral exploration. Variations in electrical impedance of the earth's crust to naturally occurring electromagnetic waves are calculated and mapped based on surface measurements of preferably both the magnetic and electric fields.

Magnetotelluric research overview - University of Washington.
Magnetotelluric Network - An international electronic forum for the free exchange of knowledge, programs and data between scientists engaged in the study of the Earth using electromagnetic methods, principally the magnetotelluric technique.

Commercial Example:

Electromagnetic Instruments, Inc.- MT sensing including transmitters which supplement the natural fields at certain higher frequencies for shallower depths and marine (ocean floor) systems for oil. An example impedance map for gold prospecting.

Allied topic: Electrical Resistance Tomography (ERT)
ERT is a technique for obtaining subsurface images at depths of 10 to 500 feet by the measurement of electrical conductivity variations.

Electrical Resistance Tomography - 34 page Lawrence Livermore National Laboratory (LLNL) Report, pdf format.
Electrical Resistance Tomography (ERT) - shorter reference giving the basics of ERT including FAQ's and images, LLNL. See also the LLNL IPAC page.
An Overview of Electrical Tomographic Measurements in Pharmaceutical and Related Application Areas, full length article available online by G.T.Bolton, K.M.Primrose, Industrial Tomography Systems, Manchester,UK.

>>>MICROFLUIDICS and Array Technologies (technologies used in lab-on-a-chip; biochips; gene chips; total analysis systems TAS; microreactors; mixers)

Gene-chips (DNA Microarray) page - an excellent database courtesy of Dr. L. Shi.
Ultrasonic microfluidic devices - research at UC Berkeley.
Dog-on-a-chip - large scale nanotechnology.

Commercial Examples:

Caliper Technologies Lab-on-a-chip manufacturer.
Coventor - software for designing microfluidics devices.
Orchid Cellmark - (formerly Orchid Biosciences and Biocomputer) - SNP-IT tag array.
Micronics - H-filter, T-sensor, Microcytommetry, ORCA microfluidics.
Lab-On-A-Chip / BioMEMS Systems CFDRC - a contract R&D company.

>>>MOISTURE IN GASES
Technologies and commercial examples:

Aluminum oxide type - applications HVAC,clean rooms, respiratory treatment rooms, etc. General Eastern (now part of GE Sensing).
Chilled mirror hygrometers - Buck Research.
Technical articles and application notes - GE.
Nyad - capacitive, ppm level sensitivity (down to -130C dewpoint).
Honeywell integrated absorption capacitive relative humidity/temperature sensors; polymer based, applications include refrigeration, drying and meteorology.
Hygrometrix - Shear/stress strain gauge types, measure RH.
CRDS - Cavity ring down spectroscopy - ultra sensitive laser based IR absorption detection principle intended for semiconductor gas applications - Tiger Optics.
Tracer - 1 ppb sensitivity electrolytic by Meeco.
High temperature humidity measurement - up to 2400F, MAC Instruments.

>>>>OIL IN WATER; WATER IN OIL
In the oil industry water in oil sensors are called water cut meters, while oil in water are often called oil cut meters. Technologies include UV fluorimetry, dielectric constant measurements, microwave resonance (measures both dielectric constant and conductivity) and neutron probes.

Neutron radiography- a certain type of 'neutron probe' for detecting moisture, Cornell Univ.
Multiphase Flowmetering - part 1 part2 - AGAR Corporation.

Commercial examples:

UV Aquatracka - environmental - deeply submersible high sensitivity fluorimeter - principally for undersea oil pipeline leak detection, Chelsea Instruments Ltd.
Oil in water monitors - UV Fluorescence; multiple applications; Turner Designs Hydrocarbon Instruments, Inc. <LS>
Water in oil sensor - dielectric constant measurement; Eesiflo. <LS>

Oil industry:
Multiphase flowmeters and water-cut meters - Roxar.
Oil in water - microwave load-pull - Phase Dynamics.
Water cut - using time domain transmissometry - ESI.

>>>>POSITION SENSORS
The category of position sensors is usually taken to refer only to linear and angular displacement. However, it can also refer to sensors used for determining spatial location in a broader sense, including GPS, navigational sensors and so on.

Position transducers - a brief review of optical encoders, LVDT (linear variable differential transformer), magnetostrictive linear displacement transducer, (MLDT), resistive and inductive types.
Fundamentals of Electroacoustics - an introduction to ultrasonic transducers with an emphasis on ranging applications in air and water - MASSA.
Macrosensor - Tutorial on LVDT position sensors. <SRC LE>
Position Measurement & Control - a free newsletter downloadable in .pdf format provided by SpaceAge Control, Inc.
GPS Tutorial - Courtesy of Trimble.
Precision navigation - an online tutorial covering inertial navigation systems (INS), global positioning system (GPS) and Doppler velocity sensors (DVS), University of New Brunswick, Geodesy Group.

Commercial examples:

Magnetostrictive - Turck.
Novotechnik - Applications for inductive, capacitive and conductive position sensors in medical, plastics manufacturing and automotive. <LS>
Magnetic position sensors and Ultrasonic position sensors. Honeywell.
Optical position sensitive detectors - can be used for non-contact distance measurement, laser beam alignment and optical tracking of an object, Hamamatsu Photonics.
Position sensing systems - location in 3D space. Ascension Technology Corporation.
Capacitive Position Gauge for Nanometrology Applications - PI

>>>>REMOTE SENSING
The term "Remote sensing" most commonly refers to earth satellite based sensing, but also describes remote sensing from other platforms.

Remote sensing tutorial - GIS Development: The Geospatial Resource Portal
Remote sensing technologies in viticulture UNE, Australia.
Airborne Sensor Facility - NASA Ames Research Center.
Remote Sensing Tutorial - an online version of a large course, courtesy of N. Short, NASA Goddard Space Flight Center.
NASA Space Instrument and Sensing Technology - This page contains information on NASA's Instrument and Sensing Technology development programs. For example see a review of Satellite Laser Ranging Technologies. (a smaller, less up-to-date site)

>>>>RFID / smart tags
The development of RFID (radio frequency identification) was and is largely driven by smart packaging for supply chain management by large retail companies. However, a host of additional applications are currently emerging.

RFID Research Group at UNT - a library site including links to . Articles on RFID, whitepapers, including an RFID Primer and more
RFID Journal - "technology news and features" - focuses mainly on industry issues.
Announcement of World's first RFID sensor chip for DNA analysis - Hitachi.

Commercial:

RFID - a company site which also provides useful information about the various types of RFID devices including RFID sensors. TagSense.
KSW Microtec - Smart active labels with integrated temperature sensor. Brief pdf
RFID & Asset Tracking - Crossbow Technology, Inc.

>>>>SAW SENSORS (Surface Acoustic Wave)
SAW devices are high frequency electronic filters which also have a number of sensing applications including vibration, displacement, torque, moisture, gas and liquid sensing and as passive receivers and transmitters in RFID devices.

Advances In Surface Acoustic Wave Technology, Systems and Applications, ed. Clemens C W Ruppel & Tor A Fjeldly, Oct.2000, World Scientific Publishing.
A Review of Wireless SAW Sensors, A. Pohl, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, Vol 47, No2, March 2000, 16 pages, full text in pdf format. Includes a section on applications, including sensors for the "intelligent tire".
Transense Technologies plc - automotive tire pressure and torque.
Review of Chemical Sensors for the In-Situ Monitoring of Volatile Contaminants, Sandia Report, March 2002. Pdf 34 pages. See sections 2.1.3 micro Chem Lab., and 2.3 Surface Acoustic Wave Sensors/Portable Acoustic Wave Sensors, which also contains active links to current development activities at Sandia and elsewhere. See also SAW Chemical Microsensor Arrays and Integrated SAWs using GaAs
SAW Sensor Systems - applications include passive RFID and temperature. Site also includes an explanation of the principles of operation for temperature sensing and RFID combined. Carinthian Tech Research.

>>>>TEMPERATURE SENSORS
Contact methods include thermocouples, thermopiles, negative and positive temperature coefficient (NTC, PTC), thermistors, which are fabricated from various semiconductor materials, platinum, nickel and copper RTD's (resistive temperature devices), liquid in glass, semiconductor junction. Non contact methods include IR radiometers and pyrometers, thermographic imaging cameras using quantum detectors, bolometer arrays and pyroelectric materials. Passive imaging systems are also referred to as FLIR systems - forward looking infra red. Applications are extensive including medical, power distribution inspection, building heat loss and so on.

Temperature Sensing - a well-organized "information repository on devices that measure temperature" courtesy of Ray Peacock. See also TempSensor.net
Temperature World - temperature news, resources and links.
Articles on temperature sensors, including a very comprehensive technical discussion of temperature, about temperature, plus thermocouple charts and RTD charts; Thermometrics Corp. <SRC LE>
Thermometrics is in fact a different company and is a division of GE Industrial. Thermometrics focus on thermistors. What is a thermistor. Site provides a range of NTC and PTC thermistor application notes. Also see an interesting IR thermopile MEMS sensor under the name GE Thermometrics Technologies Ltd.

>>>>TERAHERTZ (THz) imaging and spectroscopy
THz lies between the far infrared and microwave portions of the EM spectrum. It is considered safe to living tissue and can penetrate nonconductive materials allowing imaging through, for instance, clothing and walls, plus it can be used to detect the presence of many different chemical species that have vibrational and rotational spectra in that frequency range.

THz Science and Technology - an informative site from one of the leading THz R&D groups, Center for THz Research, RPI. See for instance about THz wave and THz Sensing and Imaging

Commercial examples:

Teraview - site describes multiple applications in medical, security, material and molecular structure characterization.
Thruvision - security screening.

top of page

Biomedical

The WWW Virtual Library of Biotechnology A significant resource. " This field covers biotechnology, pharmaceutical development, genetic engineering, medical device development, and related fields such as pharmacology and toxicology …. emphasis on product development and the delivery of products and services."
The WWW Virtual Library of Biosciences
Harvard Department of Molecular and Cellular Biology - Biology links
FDA US Food and Drug Administration
Bio Online - a web resource for life sciences.
Medical Device Link by Canon Communications, LLC provides supplier directories, links, a database of consultants and online articles from several trade magazines including Medical Device & Diagnostic Industry
GASNet - "The world's first globally distributed anesthesia server network" - maintained by Yale University
Photobiology online - A cooperative presentation of the European and American Societies for Photobiology "Photobiology is that branch of biological science which studies the interactions of light with living organisms." - site includes reference data.
National Biophotonics Resource "The NBR is a NIH Biomedical Resource dedicated to the application of photon based techniques for the study of dynamics of living systems." - a fascinating site hosted by the University of Wisconsin.

Guide to Pulmonary Artery Catherisation by Andrew Pybus - a comprehensive online text concerning PAC which is geared towards medical and nursing staff.
Spirometry Handbook The measurement and Interpretation of Ventilatory function in Clinical Practice by R. Pierce, MD and D.P. Johns, Ph.D.
The Basics of MRI, an excellent hyper-textbook written by Joseph. P. Hornak, Ph.D, concerning clinical magnetic resonance imaging.
Introduction to Pulse Oximetry, a web site dedicated to pulse oximetry.
Capnography/Capnometry during Mechanical Ventilation, AARC Clinical Practice Guideline, Reprinted from Respiratory Care [Respir. Care 1995;40(12):1321-1324].
Clinical Ultrasound, PPT file, Basic principles by Dr. Katherine Ferrara, Dept. of Molecular & Medical Pharmacology, UCLA, 1999.
Jounal of Clinical Ultrasound, Wiley.
CHORUS, Collaborative Hypertext of Radiology, Medical College of Wisconsin.
Journal of Diagnostic Radiography and Imaging, RSM Press.
Metabolic measurements using indirect calorimetry During Mechanical Ventilation 2004 Revision & Update, AARC Clinical Practice Guideline, Respiratory Care Journal.
Medical trace gases, Infrared Laser Spectroscopy Group, Heinrich Heine Universitat, Dusseldorf. [Breath gas analysis for trace gases is receiving interest as a diagnostic technique because the presence of trace amounts of certain gases has been linked to a range of specific patient conditions.]
Optical Nose Technology competes with breathalyzers and blood tests, Laser Focus World.
Description of a miniature implantable drug delivery pump - extremely small, self-contained pumps for delivering down to 4nL/min, Eksigent Medical.

>>Some R&D Projects

Veterinary telemedicine - An NSF funded project to research and develop intelligent, mobile medical monitoring devices for cattle herds. Results are expected to have application to distributed medical systems for humans as well as cattle. Dept. Computing and Information Sciences, Kansas State Univ.
A new spirometer mouthpiece, - spirometer mouthpieces are small flow sensors. This is a brief summary of an SRC R&D project.
Design of a Biodiagnostic chip - to be worn on the wrist in a wristwatch package. A CFDRC project conducted in conjunction with Univ. Cincinatti, see MicroSystems and BioMEMS Lab
Miniaturize Artificial Nose System for Medical Application - an R&D project to develop technology to detect trace breath gases as an advanced diagnostic technique for a series of patient conditions. F.K.C. Harun, Sensors Research Laboratory, Engineering, Univ.Warwick, UK.
Tracking Information Flow in the Brain - R&D at MIT on a calcium nanosensor.

>>Commercial examples of biomedical sensors:

Tissue vitality monitoring - In-vivo, real-time, fiber optic microsensors from Oxford Optronix. ptO2 via fluorescence, (pdf article), blood flow via laser Doppler, (pdf article) and tissue temperature.
Fiber optic pressure and temperature sensors for medicine - based on Fabry-Perot cavity - RJC Enterprises, LLC.
Impedance cardiography - a system for non-invasive cardiac output and other hemodynamic parameters and a system for determining skin perfusion / microcirculatory health - Vasamed (formerly Optical Sensors, Inc.)
Pulse oximeters - Nellcor.
Pulse oximeters ; Patient monitors; and a vast range of medical instrumentation (see also the company web site map) - all from the giant GE Healthcare, (currently plans to acquire the Finnish company Instrumentarium - which is Datex in the US).
Ingestible thermometer pill - HQ Inc.
SmartPill GI Monitoring System another ingestible sensor which instead transmits pressure, pH and temperature as it transits the GI tract. (not yet released) SmartPill Corp.
Real-Time Continuous Glucose Monitoring - Medtronic MiniMed.
Implantable blood glucose sensor - under development by SMSI.
Intraoperative, Perivascular Flowprobes - miniature ultrasonic probes that are designed for flow measurements during surgery. Transonic.
Locating medical instruments in 3D space - using magnetic tracking - Ascension Technology.Corporation.

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Research Centers (see also Universities)

NASA Langley Research Center
NASA Ames Research Center
NASA Glenn Research Center
NASA Jet Propulsion Laboratory - the JPL Technical Reports Server gives access to nearly 7000 JPL research reports.
David Sarnoff Research Center
MCNC (formerly the Microelectronics Center of North Carolina)
Sandia National Labs
Sensor Technology at the Lawrence Livermore National Lab - brief details of 40 or 50 different projects - the pages have not been updated for several years (!) but the content is nevertheless interesting.
Biosensors at ORNL - development activities on biosensors and other medical and environmental sensors, for example a 2 × 2-millimeter silicon chip attached to the skin that can measure body temperature. The chip contains a temperature sensor in an integrated circuit, a lithium thin-film battery that supplies the very low level of power required by the circuit and signal processing and transmission electronics, and an antenna that sends the data by radio signals to a monitor when the chip is queried. Ferrell (ORNL) calls this biosensor a "medical telesensor ASIC" and expects that a chip can also be developed to measure blood oxygen level.
Pacific Northwest National Laboratory (PNNL) - Sensors & Electronics - work on biological, chemical, physical property and nuclear radiation sensors.
Bell Labs (Lucent Technologies)
The Royal Institution of Great Britain Established by Royal Charter in 1799: The oldest independent research establishment in the world.
Division of Materials Research, NSF
Woods Hole Oceanographic Institution
Oceanographic research laboratories - a comprehensive listing to "laboratories and universities active in marine biology and physical oceanography", provided by Open Seas Instrumentation, Inc. <LS>
The International SeaKeepers Society - sensor R&D. Seakeepers is a nonprofit organization that actively protects the oceans by equipping luxury yachts, other vessels, and platforms around the world with sophisticated ocean and atmospheric monitoring sensors.
NOAA Environmental Technology Laboratory - a government lab which performs research and develops oceanic and atmospheric remote sensing systems, including LIDAR and radar techniques, in support of NOAA's environmental monitoring charter.
Mount Washington Observatory
National Renewable Energy Laboratory
Battelle
Delft Institute of MicroElectronics and Submicron Technology - DIMES - "The mission of DIMES is to be an international center of excellence dedicated to promoting research and training in micro- and nanoelectronics through infrastructure, technology development, and innovation in process, device, circuit and system technologies." Four research themes: high frequency technology for communications; integrated smart microsystems; nano-electronics; large-area electronics.
EPRI - The Electrical Power Research Institute.
SI&NDE The sensors, instrumentation and nondestructive evaluation section. Argonne National Lab.
Gas Research Institute.
NSF Grants Database - updated weekly - provided by the Community of Science.
Fraunhofer Technology Center Hialeah - the U.S. subsidiary of "Europe's largest applied research organization"
Centre for Chemical Sensors (CCS) at ETH Zurich - research on optical, potentiometric and amperometric chemical sensors and biosensors. Site also provides links to other European R&D groups working on chemical sensors.

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Universities

University websites can be a significant source of information, including descriptions of current research, online literature, library facilities, conferences, meetings, links and so on. Many of the sites are large. In the US the URL's are often http://www.universityname.edu/
UK Universities Image Sensitive Map This map provides links to the websites of all the Universities in the UK - start here and explore.
Web U.S. Universities by State courtesy of the University of Texas at Austin
U.S. Colleges & Universities by State courtesy of the University of Hartford <LS>
California Institute of Technology (http://www.caltech.edu/)
Carnegie Mellon University - have a range of research centers including The Robotics Institute
University of California at Berkeley. (See also: Berkeley Sensor & Actuator Center)
UCLA For instance the Department of Mathematics offers a series of research articles via FTP.
University of Southern California for example review projects at USC's Biomedical Simulations Resource.
University of Cincinnati (see also The Center for Microelectronics & MEMS)
University of Maine (research includes their Sensors Technology Laboratory)
Michigan State University (see the NSF Center for Sensor Materials)
Princeton University (research includes for example Gas Dynamics and Fluid Dynamics )
Terahertz Research Groups and Facilities links provided by THz group at RPI
Rutgers University
Ohio State University - Center for Industrial Sensors and Measurements and the Center for Materials Research
Penn State - see for example, the International Center for Actuators and Transducers (ICAT) at the Materials Research Laboratory, designated as "the world center for fundamental research on actuator and transducer materials, the design and fabrication process, as well as the applications of solid state actuators to precision machines, micropositioners, ultrasonic motors, etc."
University of Pennsylvania - see List of Research Centers and Institutes
Nanosensors for Aqueous Environments - one part of an NSF EPSCor research program, Univ. Idaho.
Stanford University - hosts two well-known sensors research facilities, namely the Micro Structures & Sensors Laboratory and the Stanford Transducers Laboratory, as well as the Center for Turbulence Research an internationally recognized institution for turbulence research.
S-SENCE Swedish Sensor Centre. Centre for bio- and chemical sensor science and technology, Linkopings University.
Biosensors at the Cranfield Biotechnology Centre - University of Cranfield - extensive.
Center for Biologically Inspired Materials & Material Systems - Duke University.
Sensors Research Laboratory - Univ. Warwick, U.K.
National Centre for Sensor Research - Dublin City University.
Microsystem Technology Lab, Signals Sensors & Systems, School of Electr. Eng., Royal Institute of Technology, (KTH), Stockholm.
University of Illinois at Chicago see the Microfabrication Applications Laboratory and Microfluidics Lab.
Micro Nano Technology Research Group, Dept. Electrical and Computer Engineering, Univ. Illinois at Urbana-Chapaign. The micro and nanotechnology laboratory focuses on microscale and nanoscale fabrication technology, bioinspired sensors, and multiscale integrated systems. For example: they "have developed an artificial MEMS haircell sensor.
MIT - for example Crystal Physics and Electroceramics Laboratory and MIT Touch Lab
Yale University
At Twente University, Netherlands, see Micromechanical Transducers Group at the Mesa Institute and the Laboratory for Biomedical Engineering
Sensors research at the Institute of Physical and Theoretical Chemistry, University of Tubingen, Germany.

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Standards Organizations, Institutions and Information

ISO International Organization for Standardization, (Switz.) Also provides links to worldwide standards organizations.
NIST The National Institute for Standards and Technology (USA). See also the NIST Physics Laboratory
NPL The National Physical Laboratory is the UK measurement standards laboratory. Useful information plus one or two fun things. For instance you can see a descendant of Newton's apple tree! and there's an online barograph, should you need to know the barometric pressure at Teddington very accurately.
INMS - "The Institute for National Measurement Standards (INMS) draws together activities at Canada's National Research Council related to metrology to provide the foundation for Canada's National Measurement System…."
National Standards Systems Network A national resource for global standards maintained by ANSI -provides a free search for standards by a single word, developing agency's name, title or number.
ANSI American National Standards Institute. ANSI also provide a searchable catalog.
API American Petroleum Institute - search, order and download API standards.
WWW Virtual Library of Standards and Standardization Bodies
ASTM American Society for Testing and Materials - an informative site offering a search of ASTM standards and the ASTM International Directory of Testing Laboratories.
IEC - International Electrotechnical Commission.
IEEE Standards
ISA Standards Information.
NEMA Electrical Standards
ETSI The European Telecommunications Standards Institute - this site also provides a publications search where "You can now access the complete range of ETSI Publications, including European Standards in the telecommunications series (EN, ETS, I-ETS, EG, ES, ETR, GTS, TBR, TR, TS)."

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Units, conversion factors, etc.

International System of Units (SI) - part of the NIST reference on constants, units and uncertainty site - provides descriptions of the seven SI base units, example derived SI units, rules and style conventions for manuscripts, base unit definitions, for example, "The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.".
SI Manual in Healthcare, 2nd edition - SI units and conversion factors relevant to healthcare - written to assist the transition to SI in Canada - a collaborative program of the Hamilton Health Sciences Corporation, St. Joseph's Hospital and McMaster University.

>>>>CONVERSION FACTORS

Many web conversion factor calculators and tables look good but do not indicate the source or accuracy for the numerical values they use. It is strongly recommended that conversion factor values obtained from the following links or elsewhere are always cross checked.

Pressure units converter - provided by Omega.
Thermal Wizard - this resource includes a page of unit conversion calculators plus calculators for heat transfer and more. Provided by MAYA Heat Transfer Technologies, Ltd.
Online calculators for light measurements - International Light Technologies.
A Units Conversion Calculator - from Ocean News & Technology for length, area, volume, pressure velocity, weights and density.
Online conversion - a variety of calculators for different fundamental parameters as well as some less technical parameters.
Asknumbers.com Similar to online conversion.

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General interest

- serious

Acronyms list An extensive list of organization and technical acronyms, courtesy of NIST.
AGU - American Geophysical Union "dedicated to advancing the understanding of Earth and its environment in space and making results available to the public." - incorporates a science for everyonesection which features many well-written online articles organized into 8 subsections ranging from Atmospheric sciences to Space sciences.
American Association for the Advancement of Science - review the latest data on congressional appropriations for R&D - connect to Science magazine.
EEVL - an extensive well-maintained site offering a searchable catalogue of reviews and links to engineering Web sites, indexes to print literature and other specialist information services.
Encyclopaedia Britannica Online
Eric Weisstein's Mathworld - an extensive and perhaps the best mathematics web database.
ICSU - International Council for Science. "ICSU is a non-governmental organization, founded in 1931 to bring together natural scientists in international scientific endeavor. "
Industry Week - see for instance Industry Week's selection of the world's 50 best-managed companies.
Nature - the International weekly journal of science.
New Scientist
Mechanical Engineering Magazine Online published by ASME.
Oil online a site specifically designed for those involved in the oil industry. Based in Houston, TX.
Oil and Gas Online
PetroMin Magazine - "Asia's oil & gas exploration and production magazine". <SRC LE>
Pneumatics online - "the reference source for the pneumatics industry"
Tech Online - a series of web sites related to electronics engineering, including, among others, DSPnet, Embeddednet and the Tech Online University. Free registration.
SPIE - The International Society for Optical Engineering
The Scientist - "the news journal for the life scientist".
The Academy Complex - made up of the National Academy of Sciences, National Academy of Engineering, Institute of Medicine and the National Research Council. The NAE section of this site provides links to over 50 Professional Engineering Associations and Societies.
USGS - The U.S. Geological Survey.
W3C - The World Wide Web Consortium - provides the WWW Virtual Library which is a large collection of libraries in many different fields including science and engineering. For example the engineering section has libraries ranging from Acoustics and Vibrations to Welding Engineering
Nanotechnology links:
US National Nanotechnology Initiative
Nanotechweb - nanotechnology news and information from IOP.
Royal Society Survey of Nanotechnology
Lookstoogoodtobetrue run by a joint industry/law enforcement group, was built to educate consumers and help prevent them from becoming victims of Internet fraud schemes.
The World Factbook - CIA

>>>>GLOBAL WARMING
Also referred to as anthropogenic climate change

Intergovernmental Panel on Climate Change established in 1988, the purpose of the IPCC is to assess the state of knowledge on the various aspects of climate change including science, environmental and socio-economic impacts and response strategies.
Hadley Centre - UK Met Office is leading international research into what could happen under climate change, and the impacts on current and future generations. In my opinion this is the best site on the Internet for obtaining a reasonable, overall technical appreciation for this subject. The site outlines the factors involved, current data, the various climate models and the results of projections based on various scenarios.
Climate Change 2001: The Scientific Basis IPCC report.
Climate Change 2007: The Physical Science Basis; Summary for Policymakers IPCC report, pdf.
Carbon dioxide capture and storage - Summary for policy makers (62 pages, pdf file) - IPCC.
Introduction to Climate Change - United Nations Environment Programme / GRID Arendal.
Kyoto Protocol - what it is, country signatories, etc. - Wikipedia.
USGS - Global warming archive (this is only one small section - the USGS site is worth hunting through).
Impacts of Volcanic Gases on Climate, the Environment, and People - U.S. Geological Survey Open-File Report 97-262.
Atmospheric Aerosols and Global Climate - research at the University of New South Wales.
Climate change - some basics; this is a relatively short article written by a self described, non-expert, dated 1997; (J. Schloerer, Ulm University). I included this particular link reference because I personally found that it gives a quite reasonable, quick-read technical synopsis of the basic science involved. However, the article is otherwise out of date and the interested reader should refer to sources of more recent information concerning current trends, data and the more pronounced current convergence of informed scientific opinion.
ClimatePrediction.Net gateway Climate prediction.net is claimed to be "the largest experiment to try and produce a forecast of the climate in the 21st century." Read about it. This is a distributed computing project for running climate model predictions. I am not a fan of turning my PC over to outside control and I have not participated in this particular experiment. I therefore cannot provide any recommendations or comments concerning the overall effects and potential effects on a typical home, or otherwise, PC. If you decide to participate I recommend that you first research the site fully concerning those issues.

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- fun

The World Wide Web Virtual Library of Museums Undoubtedly the best online resource for the world's museums and galleries with mirror sites around the world.
A Virtual Space-Time Travel Machine An extensive and growing collection of unusual images which includes a large number of sophisticated visualizations of physical and mathematical processes, ranging from fluid mechanics to astrophysics and fractals.
Astronomical pictures & animations - "An online 4.8 gigabytes astronomical server."
Movies from the Edge of Spacetime - simulations depicting the "..dynamic behavior of black holes and gravitational waves" - National Computational Science Alliance, University of Illinois.
megaConverter - more than just a units converter.
ScienceDaily Magazine - an Internet magazine which is updated daily claiming "..your link to the latest research news" - light reading, well presented.
Your dictionary dot com This site provides access to a range of online dictionaries for over 300 languages.
The home page includes an online English dictionary and Thesaurus and word translation dictionaries between English and 5 other languages.

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