Rational materials design based on prior knowledge is attractive because it promises to avoid time-consuming synthesis and testing of numerous materials candidates. However with the increase of complexity of materials, the scientific ability for the rational materials design becomes progressively limited. As a result of this complexity, combinatorial and high-throughput (CHT) experimentation in materials science has been recognized as a new scientific approach to generate new knowledge. This review demonstrates the broad applicability of CHT experimentation technologies in discovery and optimization of new materials. We discuss general principles of CHT materials screening, followed by the detailed discussion of high-throughput materials characterization approaches, advances in data analysis/mining, and new materials developments facilitated by CHT experimentation. We critically analyze results of materials development in the areas most impacted by the CHT approaches, such as catalysis, electronic and fun...

Combinatorial and High-Throughput Screening of Materials Libraries: Review of State of the Art

Modern gas monitoring scenarios for medical diagnostics, environmental surveillance, industrial safety, and other applications demand new sensing capabilities. This Review provides analysis of development of new generation of gas sensors based on the multivariable response principles. Design criteria of these individual sensors involve a sensing material with multiresponse mechanisms to different gases and a multivariable transducer with independent outputs to recognize these different gas responses. These new sensors quantify individual components in mixtures, reject interferences, and offer more stable response over sensor arrays. Such performance is attractive when selectivity advantages of classic gas chromatography, ion mobility, and mass spectrometry instruments are canceled by requirements for no consumables, low power, low cost, and unobtrusive form factors for Internet of Things, Industrial Internet, and other applications. This Review is concluded with a perspective for future needs in fundament...

Multivariable Sensors for Ubiquitous Monitoring of Gases in the Era of Internet of Things and Industrial Internet

Wireless sensors are devices in which sensing electronic transducers are spatially and galvanically separated from their associated readout/display components. The main benefits of wireless sensors, as compared to traditional tethered sensors, include the non-obtrusive nature of their installations, higher nodal densities, and lower installation costs without the need for extensive wiring.1–3 These attractive features of wireless sensors facilitate their development toward measurements of a wide range of physical, chemical, and biological parameters of interest. Examples of available wireless sensors include devices for sensing of pH, pressure, and temperature in medical, pharmaceutical, animal health, livestock condition, automotive, and other applications.4–7

Some implementations of wireless gas sensors can be already found in monitoring of analyte gases (e.g. carbon dioxide, water vapor, oxygen, combustibles) in relatively interference-free industrial and indoor environments.8,9 However, unobtrusive wireless gas sensors are urgently needed for many more diverse applications ranging from wearable sensors at the workplace, urban environment, and battlefield, to monitoring of containers with toxic industrial chemicals while in transit, to medical monitoring of hospitalized and in-house patients, to detection of food freshness in individual packages, and to distributed networked sensors over large areas (also known as wireless sensor networks, WSNs). Unfortunately, in these and numerous other practical applications, the available wireless gas sensors fall short of meeting emerging measurement needs in complex environments. In particular, existing wireless gas sensors cannot perform highly selective gas detection in the presence of high levels of interferences and cannot quantitate several components in gas mixtures.

1.1. Diversity Of Monitoring Needs Of Volatiles
The monitoring of numerous gases of environmental, industrial, and homeland security concern is needed over the broad range of their regulated exposure concentrations. Figure 1 illustrates the relationships between several regulated exposure levels spanning several orders of magnitude of gas concentrations. Typical examples of concentrations of regulated exposure are presented in Table 110–14 for three groups of toxic volatiles such as volatile organic compounds (VOCs), toxic industrial chemicals (TICs), and chemical warfare agents (CWAs). These examples demonstrate the need for gas sensing capabilities with broad measurement dynamic ranges to cover 2 – 4 orders of magnitude in gas concentrations.



Figure 1

Examples of regulated vapor-exposure limits established by different organizations: 

GPL: General Population Limit, established by USACHPPM – U.S. Army Center for Health Promotion and Preventative Medicine;


PEL: Permissible Exposure Limit, established


...





Table 1

Examples of regulated concentration levels (in ppm by volume) from three representative classes of toxic gases: VOCs, TICs, and CWAs.10–14



Additional needs for detection of volatiles originate from medical diagnostics, food safety, process monitoring, and other areas.15–17 In those applications, the types and levels of detected volatiles can provide the needed information for further control actions.

/pdf/materials-and-transducers-toward-selective-wireless-gas-1gh8vl1pkn.pdf

Materials and transducers toward selective wireless gas sensing.

Market demands for new sensors for food quality and safety stimulate the development of new sensing technologies that can provide an unobtrusive sensor form, battery-free operation, and minimal sensor cost. Intelligent labeling of food products to indicate and report their freshness and other conditions is one important possible application of such new sensors. This study applied passive (battery-free) radio frequency identification (RFID) sensors for the highly sensitive and selective detection of food freshness and bacterial growth. In these sensors, the electric field generated in the RFID sensor antenna extends 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 milk freshness, fish freshness, and bacterial growth in a solution. Unlike othe...

/pdf/battery-free-radio-frequency-identification-rfid-sensors-for-4f3lf7bowx.pdf

Battery-free radio frequency identification (RFID) sensors for food quality and safety

Aspects of the subject disclosure may include a planar antenna configured to transmit first signals as a first guided electromagnetic wave that is bound to a surface of a transmission medium, wherein the first guided electromagnetic wave propagates along the surface of the transmission medium without requiring an electrical return path, wherein the planar antenna includes an array of patch antennas that generates first near field signals in response to the first signals and a plurality of directors configured to guide a portion of the first near field signals from the array of patch antennas to the surface of the transmission medium, and wherein the portion of the first near field signals combines to induce the first guided electromagnetic wave that is bound to the surface of the transmission medium.

Antenna system with planar antenna and directors and methods for use therewith

Selective vapor sensors are demonstrated that involve the combination of (1) organic electronic sensing materials with diverse response mechanisms to different vapors and (2) passive 13.56 MHz radio-frequency identification (RFID) sensors with multivariable signal transduction. Intrinsically conducting polymers such as poly(3,4-ethylenedioxythiophene) and polyaniline (PANI) were applied onto resonant antennas of RFID sensors. These sensing materials are attractive to facilitate the critical evaluation of our sensing concept because they exhibit only partial vapor selectivity and have well understood diverse vapor response mechanisms. The impedance spectra Z(f) of the RFID antennas were inductively acquired followed by spectral processing of their real Zre(f) and imaginary Zim(f) parts using principal components analysis. The typical measured 1σ noise levels in frequency and impedance magnitude measurements were 60 Hz and 0.025 Ω, respectively. These low noise levels and the high sensitivity of the resonant RFID sensor structures resulted in NH3 determinations with the 3σ detection limit down to 20 ppb. This achieved detection limit was 25–50-fold better over chemoresistor sensors based on PANI films and nanowires.

Development of radio-frequency identification sensors based on organic electronic sensing materials for selective detection of toxic vapors

Monolithic rectangular coaxial lines and related transmission line resonators with dielectric support embedded within the body of the inner conductor are demonstrated in this letter. Effects of dielectric straps are thoroughly studied and conclusions are verified through simulations and experiments. A very low-loss of below 0.1 dB/cm and unloaded Q -factors around 400 are measured at Ka-band. It is shown that the high-end performance is maintained for different components distributed across a 6'' wafer.

Monolithic Rectangular Coaxial Lines and Resonators With Embedded Dielectric Support

Artificial neural network (ANN)-based modeling approach for the design of radio frequency microelectromechanical system (MEMS) switches is presented. In the proposed methodology, a finite element method analysis is performed for the switch characterization and for the creation of training and testing sets for the ANN. Developed full-wave/ANN models allow for circuit level design, simulation, and optimization in a schematic of a circuit simulator. The simulation time is reduced for two orders of magnitude, while the accuracy of the full-wave method is maintained.

ANN based electromagnetic models for the design of RF MEMS switches

We demonstrate passive (battery-free) radio frequency identification (RFID) devices for selective and sensitive chemical vapor sensing in the presence of ambient interfering gases. We developed two approaches for RFID sensing (1) when a sensing material is applied onto the resonant antenna to alter its impedance response and (2) when a complementary sensor is attached across an antenna and an integrated circuit (IC) memory chip to alter the impedance response of the sensor. In both approaches, these RFID sensors combine several measured parameters of impedance response with the multivariate analysis of these parameters. Thus, these individual sensors provide a unique capability of multiparameter sensing and rejection of environmental interferences. Sensitivity of developed RFID sensors provides detection of vapors at part-per-billion and part-per-million concentrations. Selectivity of developed RFID sensors facilitates selective quantitation of different individual vapors and their mixtures with a single sensor. Our passive RFID sensors were interrogated by the sensor reader at distances ranging from 0 to 33 cm and demonstrated their reliable operation even at the largest tested distance. In our sensing implementations, not the sensor but the sensor reader provides a 16-bit resolution and high signal-to-noise of the acquired signal. Rejection of interferences with a single sensor and the independence from costly proprietary RFID memory chips that have an analog input promise to impact numerous sensing applications.

Selective quantitation of vapors and their mixtures using individual passive multivariable RFID sensors

A rectangular coaxial line fed cavity backed patch antenna element for a Ka-band phased array at 36 GHz is presented in this paper. The antenna is fabricated by a sequential microfabrication surface micromachining process with ten structural layers. The patch is 2.8 mm long and 3.2 mm wide and has two slits for impedance matching and six holes for releasing the sacrificial photoresist. It is supported with the feeding probe and two metallic posts located in the plane with zero E-field. The electromagnetic-thermal-stress analysis and design are conducted with the finite element and finite integration codes. Individual antenna elements have impedance bandwidth of about 5.1% around 36 GHz, with simulated gain and radiation efficiency of about 6.8 dBi and 95%, respectively.

Yongjae Lee

Papers

Development of radio-frequency identification sensors based on organic electronic sensing materials for selective detection of toxic vapors

Monolithic Rectangular Coaxial Lines and Resonators With Embedded Dielectric Support

ANN based electromagnetic models for the design of RF MEMS switches

Selective quantitation of vapors and their mixtures using individual passive multivariable RFID sensors

Multi-physics design and performance of a surface- micromachined Ka-band cavity backed patch antenna