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Resources for Sensors, Measurements, Instrumentation and related Sciences

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 and selected for professional quality, relevance and content.

<LS> denotes a suggested link.

Last updated: November 19, 2010

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: R&D Magazine  See also manufacturing.net
Spectroscopy Magazine - this site includes spectroscopy tutorials mostly focused on ICP-MS, links and more.

Some other reference information sites and tutorials:

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).
Sensedu - 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 of specific types or a short course if you are completely new to sensors. Dept. Electronics Techn.,Budapest University of Technology & Economics.
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:

Advanced Imaging Absorption Spectrometer – An instrument for monitoring troposheric trace gases and aerosols - TNO.
Touch Technologies - touch screen technologies for use with computer monitors, terminals and flat panel displays – Tyco Technologies.
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>
Measuring climate change – This site provides a summary of some of the basic measurement techniques.
Sensors for Steel Rolling Mills – Kelk.


>>>>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.
 
Commercial examples:

Low g accelerometers – High g accelerometers – Gyroscopes – Microphones - 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.
LISA – An ESA/NASA joint mission to detect gravitational waves.  Three spacecraft will be positioned in sun orbit in a fixed triangular pattern each separated by 5 million km from the other.

>>>>AGRICULTURAL SENSORS

Soil moisture sensing technologies – including tensiometers, time domain reflectometry (TDF), capacitance, neutron probes, conductivity and a few others.
Dendrometers – A tutorial. Dendrometers are typically designed for the measurement of tree growth.
Phytograms- TM Irrigation management in response to plant hydration, metabolic activity, chemistry, etc. determined by in situ electrochemical sensors.
Hyperspectral imaging – A tutorial. In this spectroscopic technique individual narrow spectral regions are used as indicators of specific parameters related to crop and soil health and status. The equipment can be ground based locally or deployed on airborne or space platforms. See also for example Invasive weed mapping
Geosystems Research Institute conducts research in remote spectral imaging applied to aquatic plants as well as land based agricultural.
Satellite Imaging Corporation – describes some commercial vegetation analysis services.
Thermal infrared measurement as an indicator of plant ecosystem health - M. Susan Moran,USDA-ARS Southwest Watershed Research Center Tucson, Arizona.
Chlorophyll fluorescence – A 2000 review article – K.Maxwell, G.N.Johnson.
Portable photosynthesis measuring instruments
Laser Remote Sensing of Forest and Crops in Genetic-Rich Tropical Areas - E. Gerck, J. J. Hurtak, Lasertech
Wireless sensor networks in precision agriculture – Delft University.

>>>>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.
Center for embedded networked sensors CENS – UCLA.
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.
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.

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.
ISSNIP - Univ. Melbourne.
Bayesian Approaches to Multi-Sensor Data Fusion - O. Punska, MPhil Thesis, Univ. Cambridge, UK, 1999. (.pdf)
Sensor fusion helps buildings grow green – Intel.
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.
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 David Wadlow.
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. measurement principles
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.

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)
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.
Wiegand effect – Wikipedia.

Commercial Examples:

Hall effect sensors - 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).
 
>>>>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.- oil prospecting - Schlumberger  - site also shows 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.
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)

Ultrasonic microfluidic devices - research at UC Berkeley.
 
Commercial Examples:

Caliper Technologies Lab-on-a-chip manufacturer.
Coventor - software for designing microfluidics devices.
Micronics - H-filter, T-sensor, Microcytommetry, ORCA microfluidics.
Lab-On-A-Chip Devices 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.
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.
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.

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 newsletter provided by SpaceAge Control, Inc.
GPS Tutorial - Courtesy of Trimble.
Underwater vehicle navigation – a review paper - J. C. Kinsey, R. M. Eustice, L. L. Whitcomb. 12 commonly used sensors.

Commercial examples:

Novotechnik - Applications for inductive, capacitive and conductive position sensors in medical, plastics manufacturing and automotive. <LS>
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
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)
Canada Centre for Remote Monitoring – includes remote sensing tutorials.

>>>>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 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.

>>>>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.

Wireless Passive SAW Identification Marks and Sensors – L.M.Reindl; Clausthal Technical University. 115 page tutorial in slide format.
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.
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.
Khuri-Yakub ultrasonics group


>>>>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>
GE Sensing previously Thermonetrics. 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.

Commercial examples:

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

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Biomedical

The WWW Virtual Library of Biosciences
Harvard Department of Molecular and Cellular Biology - Biology links
FDA US Food and Drug Administration
Medical Device & Diagnostic Industry
American Society for Photobiology "Photobiology is that branch of biological science which studies the interactions of light with living organisms."
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.
Journal Respiratory Care
CHORUS, Collaborative Hypertext of Radiology, Medical College of Wisconsin.
Journal of Diagnostic Radiography and Imaging, RSM Press.
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.
Drug delivery system - extremely small, self-contained pumps for delivering down to 4nL/min, Eksigent Medical.
Complexity theory applied to health care systems

>>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.
MicroSystems and BioMEMS Lab – University of Cincinatti.
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. 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
Argonne National Lab.
Sarnoff Corporation
Sandia National Labs
Lawrence Livermore National Lab
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.
Alcatel Lucent Bell Labs
The Royal Institution of Great Britain Established by Royal Charter in 1799: The oldest independent research establishment in the world.
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  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 Earth Systems Research Laboratory
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.
 
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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
University of Southern California for example review projects at USC's Biomedical Simulations Resource.
University of Cincinnati
University of Maine
Michigan State University (see the NSF Center for Sensor Materials)
Princeton University (research includes for example Gas Dynamics and Fluid Dynamics )
Rutgers University
Ohio State University - Center for Industrial Sensors and Measurements
Penn State
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
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 Transducers Science and Technology Group
Sensors research at the Institute of Physical and Theoretical Chemistry, University of Tubingen, Germany.
Quantum Systems and Nanomaterials Group – Univ. Exeter.

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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.
INMS
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.
API American Petroleum Institute.
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.

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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.".
 
>>>>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.

Cole-Parmer – Conversion factors
Metric conversion factors
Online conversion
Asknumbers.com
megaConverter
Forest Product Conversion Factors – UN Report.
MartinDale’s Calculators On-Line Center

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The intent of this page is to provide a selection of potentially useful links.

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