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Three fingers on a new soft robotic gripper each have specialized sensors that can estimate the size and shape of an object accurately enough to identify it from a set of multiple items.  Robots have many strong suits, but delicacy traditionally hasn't been one of them. Rigid limbs and digits make it difficult for them to grasp, hold, and manipulate a range of everyday objects without dropping or crushing them. Recently, researchers from MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL) have discovered that the solution may be to turn to a substance more commonly associated with new buildings and Silly Putty: silicone. At a conference this month, researchers from CSAIL Director Daniela Rus' Distributed Robotics Lab demonstrated a 3-D-printed robotic hand made out of silicone rubber that can lift and handle objects as delicate as an egg and as thin as a compact disc. Just as impressively, its three fingers have special sensors that can estimate the size and shape of an object accurately enough to identify it from a set of multiple items. "Robots are often limited in what they can do because of how hard it is to interact with objects of different sizes and materials," Rus says. "Grasping is an important step in being able to do useful tasks; with this work we set out to develop both the soft hands and the supporting control and planning systems that make dynamic grasping possible." The paper, which was co-written by Rus and graduate student Bianca Homberg, PhD candidate Robert Katzschmann, and postdoc Mehmet Dogar, will be presented at this month's International Conference on Intelligent Robots and Systems. The hard science of soft robots The gripper, which can also pick up such items as a tennis ball, a Rubik's cube and a Beanie Baby, is part of a larger body of work out of Rus' lab at CSAIL aimed at showing the value of so-called "soft robots" made of unconventional materials such as silicone, paper, and fiber. Researchers say that soft robots have a number of advantages over "hard" robots, including the ability to handle irregularly-shaped objects, squeeze into tight spaces, and readily recover from collisions. "A robot with rigid hands will have much more trouble with tasks like picking up an object," Homberg says. "This is because it has to have a good model of the object and spend a lot of time thinking about precisely how it will perform the grasp." Soft robots represent an intriguing new alternative. However, one downside to their extra flexibility (or "compliance") is that they often have difficulty accurately measuring where an object is, or even if they have successfully picked it up at all. That's where the CSAIL team's "bend sensors" come in. When the gripper hones in an object, the fingers send back location data based on their curvature. Using this data, the robot can pick up an unknown object and compare it to the existing clusters of data points that represent past objects. With just three data points from a single grasp, the robot's algorithms can distinguish between objects as similar in size as a cup and a lemonade bottle. "As a human, if you're blindfolded and you pick something up, you can feel it and still understand what it is," says Katzschmann. "We want to develop a similar skill in robots—essentially, giving them 'sight' without them actually being able to see." The team is hopeful that, with further sensor advances, the system could eventually identify dozens of distinct objects, and be programmed to interact with them differently depending on their size, shape, and function. How it works（“We want to ... give robots‘sight’ without them actually being able to see,” says MIT grad student Robert Katzschmann. ） Researchers control the gripper via a series of pistons that push pressurized air through the silicone fingers. The pistons cause little bubbles to expand in the fingers, spurring them to stretch and bend. The hand can grip using two types of grasps: "enveloping grasps," where the object is entirely contained within the gripper, and "pinch grasps," where the object is held by the tips of the fingers. Outfitted for the popular Baxter manufacturing robot, the gripper significantly outperformed Baxter's default gripper, which was unable to pick up a CD or piece of paper and was prone to completely crushing items like a soda can. Like Rus' previous robotic arm, the fingers are made of silicone rubber, which was chosen because of its qualities of being both relatively stiff, but also flexible enough to expand with the pressure from the pistons. Meanwhile, the gripper's interface and exterior finger-molds are 3-D-printed, which means the system will work on virtually any robotic platform. In the future, Rus says the team plans to put more time into improving and adding more sensors that will allow the gripper to identify a wider variety of objects. "If we want robots in human-centered environments, they need to be more adaptive and able to interact with objects whose shape and placement are not precisely known," Rus says. "Our dream is to develop a robot that, like a human, can approach an unknown object, big or small, determine its approximate shape and size, and figure out how to interface with it in one seamless motion." Ref.KY45-TSL1401CLKY45-11242-11

This article will introduce to you how RFID sensors are applied to detecting food quality and monitoring food safety.   Catalog I. Brief Introduction II. General Principles of Design and Operation of RFID Food Sensors III. Example of Applications FAQ I. Brief Introduction   Radio frequency identification (RFID) sensors are finding their diverse applications when an unobtrusive sensor form factor, battery-free design, and minimal sensor cost are the top three requirements for a new sensor. Examples of diverse applications include pharmaceutical, warehousing, agricultural, industrial, food safety, and security.    Benefits of RFID sensors for food quality and safety, as compared to tethered sensors, include the non-obtrusive nature of their installations, higher nodal densities, and lower installation costs without the need for extensive wiring.   In addition, a significant advantage of RFID and other electronic sensors over optical sensors is in the ability to perform measurements through non-transparent packaging.   There are several developed battery-free wireless sensing technologies based on magnetoelastic,16 thickness-shear modes, surface acoustic wave, magnetic acoustic resonance, and resonant LCR (inductor-capacitor-resistor) transducers. Several approaches for battery-free RFID sensing have been explored, e.g. based on chipless RFID sensors.   We recently developed a methodology to implement passive RFID tags for physical, chemical, and biological sensing. In our RFID sensing approach, the resonance impedance spectrum of the sensor antenna is measured and further correlated with the chemical, biological, or physical properties of the environment. This correlation is performed using the multivariable response of the RFID sensor computed from the measured impedance spectrum.   The complementary driving forces in successful sensor development are innovative ideas and the market size for new sensors. The market size is often but not always is supported by the regulatory requirements. If both driving forces are strong, the sensor development moves from its initial proof-of-concept technology readiness level to the commercialization of the sensor technology.   The sizes of markets for food safety testing products ($0.25 B) and pathogen detecting sensors ($0.5 B) and provide exciting opportunities for the development of new sensing technologies for food quality and safety.   Intelligent labeling of food products to indicate and report their freshness and other conditions is one of the important possible applications of the developed RFID sensors.   Unlike other food freshness monitoring approaches that require a thin-film battery for operation of an RFID sensor and fabrication of custom-made sensors, our developed passive RFID sensing approach combines advantages of both battery-free and cost-effective sensor design and offers response selectivity that is impossible to achieve with other individual sensors.   In this review, we summarize the result of the development of RFID sensors for food quality and safety. In these sensors, the electric field generated in the RFID sensor antenna extends out from the plane of the RFID sensor and is affected by the ambient environment providing the opportunity for sensing.   This environment may be in the form of a food sample within the electric field of the sensing region or a sensing film deposited onto the sensor antenna. Examples of applications include monitoring of freshness of milk, the freshness of fish, and bacterial growth.   II. General Principles of Design and Operation of RFID Food Sensors     (Figure 1) Operation principle of developed passive RFID sensors. (A) Sensor equivalent circuit described by the inductance LA, capacitance CA, and resistance RA of the sensing antenna coil, capacitance CS and resistance RS of the sensing region, and capacitance ...   In order to assess the broad applicability of the developed sensors for food safety applications, it is critical to understand the general principles of their design and operation (see Figure 1).   The equivalent circuit of the developed sensors forms an inductor-capacitor-resistor (LCR) circuit and is described by the inductance LA, capacitance CA, and resistance RA of the sensing antenna coil, capacitance CS and resistance RS of the sensing region, and capacitance CC and resistance RC of the integrated circuit (IC) chip (see Figure 1A).   Reading and writing of digital information into the RFID sensor and measurement of the impedance of the RFID sensor antenna are performed via mutual inductance coupling between the RFID sensor antenna and the pickup coil of a digital/analog sensor reader.   Impedance spectra Ž(f) of the sensor are measured using a laboratory or a portable network analyzer component and digital data from an IC chip is measured with a digital RFID reader component29 of our custom sensor reader.   Digital data include sensor calibrations, food manufacturing data, end-user data, etc. The network analyzers are used to scan the frequencies over the range of interest (typically centered at 13 MHz with a scan range of ~10 MHz).   The electric field generated in the RFID sensor antenna extends out from the plane of the RFID sensor (Figure 1B) and is affected by the ambient environment providing the opportunity for sensing. This environment may be in the form of a food sample within the electric field of the sensing region or a sensing film deposited onto the sensor antenna.   In both cases, the impedance of the antenna circuit Ž(f) is modulated through the changes in capacitance CS and resistance RS of the sensing region. This sensing region can be in the form of a full antenna or a complementary region in contact with the antenna.32 Numerous types of sensing materials applicable for food quality sensing were recently analyzed.   To achieve accurate and precise measurements using our sensors, we measure the real Zre(f) and imaginary Zim(f) parts of the impedance spectra Ž(f) and calculate several spectral parameters.   A schematic representation of the real Zre(f) and imaginary Zim(f) parts of the impedance spectrum Ž(f) of the sensor without possible effects from a pickup coil is illustrated in Figure 1C. Several calculated spectral parameters include the frequency position Fp and magnitude Zp of Zre(f) and the resonant F1 and antiresonant F2 frequencies of Zim(f).   Additional parameters can also be calculated (impedance magnitudes Z1 and Z2 at F1 and F2 frequencies, respectively, zero-reactance frequency, quality factor, etc). From the measured parameters, resistance, capacitance, and other parameters of the resonant antenna can be also determined. Figure 2 shows examples of RFID sensors applied in our studies for food quality and safety.       (Figure 2) Examples of employed RFID sensors based on (A) Texas Instruments RFID tag, (B) Avery Dennison RFID tag, (C) TagSys RFID tag.   Uncontrolled temperature fluctuations produce independent effects on the different components of the equivalent circuit. These independent effects are correlated with the spectral features of the resonance impedance spectra and are resolved by the multivariable response of the sensor.   For scenarios when the food is irradiated by ionizing radiation as a food safety measure to destroy bacteria, pathogens, and pests,39,40 conventional RFID IC memory chips do not survive the applied radiation dose that can be up to 30 kGy.   We have developed a technical solution to solve this problem where an IC chip is based on the Ferroelectric Random Access Memory (FRAM) technology and provides reliable gamma-resistant RFID tags and sensors.   The FRAM memory chips have 2000 bytes of user memory (MB89R118A, Fujitsu Microelectronics Ltd, Japan)42 and are made using a standard RF signal modulation circuitry fabricated using a 0.35-μm complementary metal-oxide-semiconductor (CMOS) process and a non-volatile FRAM memory.43 A photo of this IC chip is shown in Figure 3A while one of our RFID sensors with such an IC chip is shown in Figure 3B.   (Figure 3) Photographs of (A) FRAM IC memory chip MB89R118A and (B) Developed RFID sensor for gamma-sterilizable applications. Sensor diameter = 10 mm. III. Example of Applications       · Monitoring of milk freshness     · Monitoring of fish condition     · Direct monitoring of bacteria growth FAQ   1. What is RFID used for? Radio Frequency Identification (RFID) is the wireless non-contact use of radio frequency waves to transfer data. Tagging items with RFID tags allows users to automatically and uniquely identify and track inventory and assets.   2. What is RFID and how it works? RFID is a method of data collection that involves automatically identifying objects through low-power radio waves. Data is sent and received with a system consisting of RFID tags, an antenna, an RFID reader, and a transceiver.   3. What RFID means? Radio Frequency Identification (RFID) refers to a wireless system comprised of two components: tags and readers. The reader is a device that has one or more antennas that emit radio waves and receive signals back from the RFID tag.   4. Is RFID harmful to human? It is a non-ionizing type of radiation, but some researches show that it could have a negative impact on the human body in a long-term period [11, 12]. So, for the safety reasons, manufacturers of the RFID systems have limited the range of the RFID antennas used in their systems.   5. Is RFID tag and FASTag same? FASTag is a device that employs Radio Frequency Identification (RFID) technology for making toll payments directly while the vehicle is in motion. FASTag (RFID Tag) is affixed on the windscreen of the vehicle and enables a customer to make the toll payments directly from the account which is linked to FASTag.   6.What is RFID and its advantages? RFID technology automates data collection and vastly reduces human effort and error. RFID supports tag reading with no line-of-sight or item-by-item scans required. RFID readers can read multiple RFID tags simultaneously, offering increases in efficiency.   7. Why is RFID bad? Some negative effects are that its deadly, if RFID tags combine with static electricity you can die. Another negative effect is that the government is slowly taking away surviving resources and giving ultimatums, such as if you don't get the RFID tracking chip your public assistance will be terminated.   8.What are the disadvantages of RFID? a. Materials like metal & liquid can impact signal. b. Sometimes not as accurate or reliable as barcode scanners. c. Cost – RFID readers can be 10x more expensive than barcode readers. d. Implementation can be difficult & time consuming.   9.How do I charge my RFID FASTag? In order to recharge your FASTag sticker, just hit the Add Money option in your Paytm app. FASTag will automatically reserve some amount from your wallet, which can be used at toll plazas later. Do note that FASTag can be used only after 20 mins of adding money to the Paytm Wallet.   10. Can I use existing RFID for FASTag? If a vehicle already has an RFID tag, it might already be activated. When you buy the vehicle, RFID tag payment was also done. It might also have a minimum balance of INR 100 or 200 as is required by the bank. You can recharge it with your Customer ID or Wallet ID of FASTag.   11. How does RFID work without power? Passive RFID tags have no power of their own and are powered by the radio frequency energy transmitted from RFID readers/antennas. The signal sent by the reader and antenna is used to power on the tag and reflect the energy back to the reader.   12. What are the types of RFID tags? RFID tags can be grouped into three categories based on the range of frequencies they use to communicate data: low frequency (LF), high frequency (HF) and ultra-high frequency (UHF). Generally speaking, the lower the frequency of the RFID system, the shorter the read range and slower the data read rate.   13.How do I know if I have an RFID chip? The best way to check for an implant would be to have an X-ray performed. RFID transponders have metal antennas that would show up in an X-ray. You could also look for a scar on the skin. Because the needle used to inject the transponder under the skin would be quite large, it would leave a small but noticeable scar.   14. Does RFID require power? Active RFID tags possess their own power source – an internal battery that enables them to have extremely long read ranges as well as large memory banks. Typically, active RFID tags are powered by a battery that will last between 3 - 5 years, but when the battery fails, the active tag will need to be replaced.   15. What is the difference between a QR code and RFID? QR codes must always be “read-only”, whereas RFID tags can be “read-write”, depending on the radio frequency that's being used. ... So, not only are RFID tags futuristic and have more uses than QR tags, they also have many more applications. The read range is far superior for an RFID tag.   Ref. KY45-R300-F35-M14-C KY78-2867704

Printed organic photodetectors and large-area image sensors company, Isorg, has announced that its first large-sized high-resolution (500dpi) flexible plastic fingerprint sensor, co-developed with FlexEnable, won the 2017 Best of Sensors Expo – Silver Applications Award. The high-resolution, ultra-thin, 500dpi flexible image sensor (sensitive from visible to near infrared) offers system integrators advantages in performance and compactness. Its ability to conform to three-dimensional shapes sets it apart from conventional image sensors. The device provides dual detection: fingerprinting as well as vein matching. Due to its large-area sensing and high-resolution image quality, the device is highly suited to biometric applications from fingerprint scanners and smartcards to mobile phones, where accuracy and robustness as well as cost-competiveness are key. Several biometric solution providers have sampled the flexible image sensor, verifying its readiness for deployment in products and compliance with FBI Image Quality Standards (IQS). “Isorg is very honoured to have received an international award for our groundbreaking high-resolution flexible image sensor technology whilst attending the most important global trade event dedicated to sensor innovations,” said Emmanuel Guerineau, General Manager and CFO at Isorg. “We are delighted to have collaborated with FlexEnable to produce the world’s first printed electronics image sensor that overcomes the limitations of traditional sensors. Biometric solution providers will be able to take advantage of the key differentiating factors that our technology brings, such as customised formats in large and small sizes, and easy integration. We see these opening up new opportunities across multiple applications.” Isorg is planning to launch high-volume production of the flexible image sensor at its new plant in Limoges, France, in order to support its large-scale commercialisation in the global biometrics market. The global biometrics hardware market is expected to grow from $3.9bn (approximately £2.99bn) in 2016 to $6.2bn (approximately £4.76bn) by 2021, according to the Yole Développement report on ‘Sensors for Biometry and Recognition 2016′. Central to the 500dpi flexible image sensor is an Organic Photodiode (OPD), a printed structure developed by Isorg that converts light into current – responsible for capturing the fingerprint. Isorg also developed the readout electronics, the forensics quality processing software and the optics to enable seamless integration in products. FlexEnable, a specialist in developing and industrialising flexible organic electronics, developed the Organic TFT backplane technology, an alternative to amorphous silicon. This partnership between the two companies began in Q4 2013. “We are delighted that the large area flexible fingerprint sensor we developed with Isorg has been recognised with such a prestigious award. Thanks to being thin, light and glass-free, the sensor can be conformed to almost any surface to enable new form factors and use cases not possible with conventional fingerprint sensors,” said Paul Cain, Strategy Director at FlexEnable. Designed on a large area (3x3.2”; 7.62x8.13cm) plastic substrate, the flexible image sensor is ultra-thin (300µ), therefore remarkably lightweight, compact and highly resistant to shock. Sensors Expo and Conference, held in San Jose, California, is the largest gathering of engineers and engineering professionals involved in sensors and sensing-related technologies. For over 30 years, it has welcomed more than 6,400 professionals from across the US and over 40 countries to explore today’s sensor technologies and find the solutions to tomorrow’s sensing challenges. The Best of Sensors Expo Awards are announced in conjunction with Sensors Online, a leading resource and authority on sensing, communication and control. The awards are designed to spotlight the advances in both innovations and real-world applications of sensors. Ref.NOIL2SM1300A-GDCMT9V022IA7ATCMT9V011

Powercast has announced what it claims to be the industry's first RFID sensor tags which can include multiple sensors in a single tag, and provide the industry’s longest read range of 10m, or 32ft. High accuracy temperature, humidity and light sensors are now available, with more sensor types planned for the future. Tags for sensing the RFID reader’s field are also available and use an on-board LED to show field strength. Designed for industrial and manufacturing applications where it’s necessary to monitor data to ensure goods don’t fall outside of acceptable parameters, the ultrahigh frequency (UHF) RFID sensor tags enable environmental condition monitoring throughout the shipping journey, for example, of temperature-sensitive pharmaceuticals or perishable products packed with dry ice. Powercast offers two versions of its high-function RFID sensor tags: 1.The PCT100 enables battery-free wireless sensing and can read data within seconds.2.The PCT200 adds a battery with the ability to recharge using any standard RFID reader’s field, making the tag reusable without plugging in or changing batteries. With up to one month of battery life without recharging, the PCT200 provides long-lasting data-logging capabilities while outside the RF field. Users can easily set its data read times from one minute to one hour. The RFID sensor tags use Powercast’s patented RF-harvesting technology where the embedded Powerharvester receiver can generate power purely from a standard RFID reader. How it works: An RFID reader generates an electromagnetic signal, which the Tag’s NXP UCODE RFID chip captures via its receiving antenna. Powercast’s efficient, RF-to-DC converter (50-75% conversion efficiency) then transforms the signal into energy to power the microcontroller and sensors for measuring environmental conditions. The microcontroller then forwards that data over I2C to NXP’s RFID chip for storage in user memory, which the reader can then read out of memory. “We call it high-function RFID because these new passive RFID Sensor Tags have more than ten times the operational power of standard passive RFID tags enabling advanced features and unparalleled computing power,” said Dr. Charles Greene, Powercast’s COO/CTO. Key features:      EPC Class 1 Gen 2 compliant     ISO/IEC 18000-6C compliant     10m read range     High accuracy sensors     Wide RF range: -17 to 20dBm     Frequency range: 860-960MHz     'Find Tag' feature – enables locating one specific tag by illuminating on-board LED     Temperature range: -40 to 85°C     Compact, convenient, hard case package     RoHS compliantHigh conversion efficiency, up to 75% The PCT100 and PCT200 can be configured with one, two or three sensors in any combination of temperature, humidity and light.The PCT100 can also be configured with an onboard LED for showing an RFID reader’s field strength and to verify that it is reading properly. Sample quantities with evaluation software are available from distributors Mouser, Arrow and Future Electronics. Ref.RF/IF and RFID   

(Random telegraph noise from single molecule was adsorbed on SWNT.) Noise is low-frequency random fluctuation that occurs in many systems, including electronics, environments, and organisms. Noise can obscure signals, so it is often removed from electronics and radio transmissions. The origin of noise in nanoscale electronics is currently of much interest, and devices that operate using noise have been proposed. Materials with a high surface-to-volume ratio are attractive for studying the noise produced by nanoscale electronics because they are very sensitive to changes of their surfaces. A representative material of this type is carbon nanotubes, which are rolled sheets of the graphene hexagonal network, which is only one carbon atom thick. A Japanese collaboration led by Osaka University has explored the ability of single molecules to affect the noise generated by carbon nanotube-based nanoscale electronic devices. The team fabricated simple devices consisting of a carbon nanotube bridging two electrodes. The devices were exposed to different large molecules, causing some to bind to the carbon nanotube surface. It was found that different molecules gave unique noise signals related to the properties of the molecules. The strength of the interaction between the carbon nanotubes and molecules was able to be predicted from the obtained noise signals. "The signal generated by the carbon nanotube device changed following the adsorption of specific single molecules," says first author Agung Setiadi. "This is because the adsorbed molecule generated a trap state in the carbon nanotube, which changed its conductance." What this means is that the carbon nanotube-based devices were so sensitive that the researchers were able to detect unique signature from single molecules. The ability to characterize single molecules using highly sensitive nanoelectronics is an exciting prospect in the field of sensors, particularly for neuro- and biosensor applications. "Use of noise signals to identify molecular activity ((interaction) or (active orbital)) is attractive for developing advanced sensing devices," explains corresponding author Megumi Akai-Kasaya. "We demonstrated that noise can be exploited to improve the signal detection ability of a device." The results of this successful demonstration will be published in the near future in a follow-up article. Signal detection sensitivity may be increased through controllable noise generation. These carbon nanotube-based devices illustrate that it is possible to detect single molecules through their unique noise signatures in the device current signals. Improved knowledge of the molecular-level origin of noise should lead to the development of electronics that use noise to improve their performance rather than degrade it.. Ref.A1321ELHLT-TAS5030-ATST 

Electrical engineers at the University of California San Diego have developed a temperature sensor that runs on only 113 picowatts of power -- 628 times lower power than the state of the art and about 10 billion times smaller than a watt. This near-zero-power temperature sensor could extend the battery life of wearable or implantable devices that monitor body temperature, smart home monitoring systems, Internet of Things devices and environmental monitoring systems.   The technology could also enable a new class of devices that can be powered by harvesting energy from low-power sources, such as the body or the surrounding environment, researchers said. The work was published in Scientific Reports on June 30.   "Our vision is to make wearable devices that are so unobtrusive, so invisible that users are virtually unaware that they're wearing their wearables, making them 'unawearables.' Our new near-zero-power technology could one day eliminate the need to ever change or recharge a battery," said Patrick Mercier, an electrical engineering professor at UC San Diego Jacobs School of Engineering and the study's senior author.   "We're building systems that have such low power requirements that they could potentially run for years on just a tiny battery," said Hui Wang, an electrical engineering Ph.D. student in Mercier's lab and the first author of the study.   Building ultra-low power, miniaturized electronic devices is the theme of Mercier's Energy-Efficient Microsystems lab at UC San Diego. Mercier also serves as co-director for the Center for Wearable Sensors at UC San Diego. A big part of his group's work focuses on boosting energy efficiencies of individual parts of an integrated circuit in order to reduce the power requirement of the system as a whole.   One example is the temperature sensor found in healthcare devices or smart thermostats. While the power requirement of state-of-the-art temperature sensors has been reduced to as low as tens of nanowatts, the one developed by Mercier's group runs on just 113 picowatts -- 628 times lower power.   Minimizing power   Their new approach involves minimizing power in two domains: the current source and the conversion of temperature to a digital readout.   Researchers built an ultra-low power current source using what are called "gate leakage" transistors -- transistors in which tiny levels of current leak through the electronic barrier, or the gate. Transistors typically have a gate that can turn on and off the flow of electrons. But as the size of modern transistors continues to shrink, the gate material becomes so thin that it can no longer block electrons from leaking through -- a phenomenon known as the quantum tunneling effect.   Gate leakage is considered problematic in systems such as microprocessors or precision analog circuits. Here, researchers are taking advantage of it -- they're using these minuscule levels of electron flow to power the circuit.   "Many researchers are trying to get rid of leakage current, but we are exploiting it to build an ultra-low power current source," Hui said.   Using these current sources, researchers developed a less power-hungry way to digitize temperature. This process normally requires passing current through a resistor -- its resistance changes with temperature -- then measuring the resulting voltage, and then converting that voltage to its corresponding temperature using a high power analog to digital converter.   Instead of this conventional process, researchers developed an innovative system to digitize temperature directly and save power. Their system consists of two ultra-low power current sources: one that charges a capacitor in a fixed amount of time regardless of temperature, and one that charges at a rate that varies with temperature -- slower at lower temperatures, faster at higher temperatures.   As the temperature changes, the system adapts so that the temperature-dependent current source charges in the same amount of time as the fixed current source. A built-in digital feedback loop equalizes the charging times by reconnecting the temperature-dependent current source to a capacitor of a different size -- the size of this capacitor is directly proportional to the actual temperature. For example, when the temperature falls, the temperature-dependent current source will charge slower, and the feedback loop compensates by switching to a smaller capacitor, which dictates a particular digital readout.   The temperature sensor is integrated into a small chip measuring 0.15 × 0.15 square millimeters in area. It operates at temperatures ranging from minus 20 C to 40 C. Its performance is fairly comparable to that of the state of the art even at near-zero-power, researchers said. One tradeoff is that the sensor has a response time of approximately one temperature update per second, which is slightly slower than existing temperature sensors. However, this response time is sufficient for devices that operate in the human body, homes and other environments where temperature do not fluctuate rapidly, researchers said.   Moving forward, the team is working to improve the accuracy of the temperature sensor. The team is also optimizing the design so that it can be successfully integrated into commercial devices.     Ref. ADT7410TRZ-REEL DS18B20