Wireless Temperature Sensor Research Articles

Passive Wireless Temperature Sensor Based on Time-Coded UWB Chipless RFID Tags

In this paper, an RF identification sensor system is developed. It comprises passive sensors and an ultra-wideband (UWB) reader. The sensors are based on time-coded chipless tags. They consist of an UWB antenna connected to a delay line that is, in turn, loaded with a resistive temperature sensor. This sensor modulates the amplitude of the backscattered signals as a function of the temperature. The sensor tags are identified by changing the length of the delay line. In this paper, the operation principle and design of time-coded tags is presented and the integration of sensors in these tags is addressed. In addition, two measurement techniques are compared to implement the UWB reader. The first one is based on frequency sweeping and uses a vector network analyzer. The second one is based on a low-cost UWB radar. A full characterization of the sensor system is provided.

A Study of Wireless Monitoring early Warning Technology of Goaf Temperature Field

With regard to goafs where spontaneous combustion of coal is very likely to occur, wireless monitoring and early warning techniques in temperature field of goaf are raised. Wireless monitoring and early warning system in temperature field of goaf based on wireless sensor network is researched and developed. Comprehensive detection, identification and early warning in temperature field of goaf are realized. Key parameters of node deployment of wireless temperature sensor in goaf are figured out and the layout schemes are optimized. According to monitored temperature information, severity of coal spontaneous combustion in goaf is figured out; therefore, early warning methods at the position of fire source are determined. Results of industrial tests on site show that monitoring data acquisition, communication are of good timeliness and reliability, operation of the entire system is stable and key functions and technical specifications can meet the need of early identification and warning of coal spontaneous combustion.

Research on Energy Saving Supervision System of Colleges and Universities Heating Based on Control Theory of Time & Temperature Sharing

According to the spirit of relative documents issued by Ministry of Housing and Urban Rural Development and by Ministry of Education, and combined with the intermittent use features of public constructions in colleges and universities, Energy saving supervision system of colleges and universities is established by using automation control technology and content networking technology. By means of installing wireless temperature sensors, time & temperature sharing controllers and electric control valves, scientific management mode of remote temperature monitoring, time & temperature sharing controlling, and on-demand heating is achieved.

Dielectric studies of barium bismuth titanate as a material for application in temperature sensors

Ceramic nanocrystalline samples with composition Ba1−3aBi2aTiO3 were synthesized by sol–gel method, for different values of parameter a (for a = 0.0165, 0.033, 0.050). In order to determine whether barium bismuth titanate is suitable for application in temperature sensors, dielectric properties measurements were conducted on the prepared samples, as a function of both temperature (from room temperature up to 190 °C) and frequency (from 50 kHz to 1 MHz). Real and imaginary parts of dielectric constant were determined using an Impedance Analyzer HP-4194A. Depending on parameter a two different behavior were determined: (1) classical ferroelectric behavior, for the sample with low a value and (2) relaxor behavior for the samples with higher a values. Thus, a typical characteristic of relaxor ferroelectrics with a broad and dispersive dielectric maximum was observed for the samples Ba0.85Bi0.1TiO3 and Ba0.90Bi0.066TiO3. Temperature dependence (for real part of dielectric constant er′) is almost linear, for lower temperatures than peak value (slope +1.3 1/ °C), and higher than this value (slope −1 1/ °C). The feature of linearity is very important from practical aspects of application of this material in wireless temperature sensors. The temperature coefficient of dielectric constant for the sample with the best linearity (Ba0.95Bi0.033TiO3 at 1 MHz) was found to vary from positive one +3.72 × 10−3 1/ °C to negative value −2.85 × 10−3 1/ °C, in the temperature range 25–190 °C.

Temperature field reconstruction for minimally invasive cryosurgery with application to wireless implantable temperature sensors and/or medical imaging

There is an undisputed need for temperature-field reconstruction during minimally invasive cryosurgery. The current line of research focuses on developing miniature, wireless, implantable, temperature sensors to enable temperature-field reconstruction in real time. This project combines two parallel efforts: (i) to develop the hardware necessary for implantable sensors, and (ii) to develop mathematical techniques for temperature-field reconstruction in real time—the subject matter of the current study. In particular, this study proposes an approach for temperature-field reconstruction combining data obtained from medical imaging, cryoprobe-embedded sensors, and miniature, wireless, implantable sensors, the development of which is currently underway. This study discusses possible strategies for laying out implantable sensors and approaches for data integration. In particular, prostate cryosurgery is presented as a developmental model and a two-dimensional proof-of-concept is discussed. It is demonstrated that the lethal temperature can be predicted to a significant degree of certainty with implantable sensors and the technique proposed in the current study, a capability that is yet unavailable.

Pseudo-orthogonal frequency coded wireless SAW RFID temperature sensor tags

SAW sensors are ideal for various wireless, passive multi-sensor applications because they are small, rugged, radiation hard, and offer a wide range of material choices for operation over broad temperature ranges. The readable distance of a tag in a multi-sensor environment is dependent on the insertion loss of the device and the processing gain of the system. Single-frequency code division multiple access (CDMA) tags that are used in high-volume commercial applications must have universal coding schemes and large numbers of codes. The use of a large number of bits at the common center frequency to achieve sufficient code diversity in CDMA tags necessitates reflector banks with >30 dB loss. Orthogonal frequency coding is a spread-spectrum approach that employs frequency and time diversity to achieve enhanced tag properties. The use of orthogonal frequency coded (OFC) SAW tags reduces adjacent reflector interactions for low insertion loss, increased range, complex coding, and system processing gain. This work describes a SAW tag-sensor platform that reduces device loss by implementing long reflector banks with optimized spectral coding. This new pseudo-OFC (POFC) coding is defined and contrasted with the previously defined OFC coding scheme. Auto- and cross-correlation properties of the chips and their relation to reflectivity per strip and reflector length are discussed. Results at 250 MHz of 8-chip OFC and POFC SAW tags will be compared. The key parameters of insertion loss, cross-correlation, and autocorrelation of the two types of frequency-coded tags will be analyzed, contrasted, and discussed. It is shown that coded reflector banks can be achieved with near-zero loss and still maintain good coding properties. Experimental results and results predicted by the coupling of modes model are presented for varying reflector designs and codes. A prototype 915-MHz POFC sensor tag is used as a wireless temperature sensor and the results are shown.

A Low-Profile Wireless Passive Temperature Sensor Using Resonator/Antenna Integration Up to 1000$^{\circ}$C

A novel wireless temperature sensor is presented herein for high-temperature applications. This sensor is robust in harsh environments using stable materials and purely passive structures. The resonant frequency of the sensor is determined by the temperature-dependent dielectric constant of the substrate material. The temperature can be wirelessly detected by sensing the resonant frequency of the sensor. The integration of the resonator and antenna enables realization of low-profile and compact sensors. Measured resonant frequency of the sensor decreases from 5.12 to 4.74 GHz when the temperature increases from 50°C to 1000°C. This corresponds to a variation of dielectric constant from 9.7 to 11.2 for the alumina substrate. The presented sensor structure is scalable in size or frequency based on the design requirements.

Multilayer test method for water vapor transmission testing of construction materials

Water vapor transmission (WVT) measurements conducted with highly permeable materials are complicated by the instability of boundary conditions, more specifically by changes in vapor pressure and air velocity on either or both sides of the specimen. Such effects pose a greater challenge in determining the water vapor transport characteristics of thin, flexible, and highly permeable construction materials. This article presents a novel approach to WVT testing that improves some of these issues. The approach denoted as ‘multilayer test’ involves testing simultaneously several vertically stacked material layers each separated by air gap with equal thickness. Wireless relative humidity and temperature sensors mounted on the opposing surfaces of each layer provide continuous temperatures and relative humidity monitoring near the specimen surfaces. The test is conducted in a controlled environment with the set-up kept on an analytical balance. Change in the weight of the system is determined automatically at predetermined time intervals, and fluxes are calculated. Two approaches are used in determining the permeance of each material layer. The results of both approaches are compared. The multilayer WVT tests provide several benefits over traditional ‘Dry’ or ‘Wet’ cup WVT test method in that; the boundary layer effects due to moving air above the specimen surface can be accounted for, and simultaneous testing of multiple specimens provides greater statistical confidence. The method is particularly advantageous in cases when the transport coefficient has a strong dependence on moisture content. Using data from a single multilayer test, a continuous transport function can be derived. This article highlights that the multilayer test approach leads to significant reduction in experimental effort, resources required for testing, and test durations, and improves the precision of the material property data.

Indoor Light Energy Harvesting System for Energy-aware Wireless Sensor Node

This paper proposes a novel energy harvesting and power management circuit that includes maximum power point tracking (MPPT) circuit, energy storage circuit, energy instantaneous discharging circuit, and DC-DC boost converter. It harvests energy from indoor faint light by imposing the harvester to work close to its maximum power point and supply power for sensor node. The measured result shows that the prototype circuit can harvest energy from indoor light condition with input power of 72.74μW and successfully drive a smart wireless temperature and humidity sensor node with power consumption of 105mW per operating cycle.

Energy scavenging system utilising MEMS switch for power management

A novel light energy scavenging system is presented, which employs a MEMS switch as the gate driver of a MOSFET in a power management circuit, for scavenging energy in ultra-low light condition. Measurements show that, in a 5lx illumination condition, the wireless temperature sensor node powered by a palm-size solar cell array can autonomously transmit RF data to a receiver 20 m away every 9 minutes. The experimental results demonstrate the most sensitive energy scavenging system ever reported, and offer great potential for realising practical self-sustaining wireless devices.

Design of Wireless Temperature Sensor Network Based on nRF905

The wireless sensor network (WSN) is the development trend of the technology of sensor. This paper, based on the nRF905 wireless module, introduces a wireless temperature gathering and transmitting system. From RF modules and master control module, the hardware platform has been designed, beyond that, the paper introduces the temperature sensor network software design. The test show that the system is stable, and datas are reliable.

Design of Wireless Temperature and Humidity Sensor Based on NRF24L01

According to the development of the Internet of things, a wireless cognitive transducer based on humidity-sensitive capacitor was designed. The ambient temperature and humidity are measured by temperature &humidity transducer which transfers the capacity into frequency signal with the help of RC oscillation, followed by the frequency with MSP430 SCM and the humidity accordingly. Thermal sensitive resister of the negative temperature system is used to measure the temperature. When measuring, the humidity can be compensated by temperature data, thus ensuring higher precision and stability of humidity measuring. The measured data are sent out by NRF24L01 through communication protocol to accomplish distant data collection of temperature and humidity, which foretells a bright prospect.

Chip Implementation with a Combined Wireless Temperature Sensor and Reference Devices Based on the DZTC Principle

This paper presents a novel CMOS wireless temperature sensor design in order to improve the sensitivity and linearity of our previous work on such devices. Based on the principle of CMOS double zero temperature coefficient (DZTC) points, a combined device is first created at the chip level with two voltage references, one current reference, and one temperature sensor. It was successfully fabricated using the 0.35 μm CMOS process. According to the chip results in a wide temperature range from −20 °C to 120 °C, two voltage references can provide temperature-stable outputs of 823 mV and 1,265 mV with maximum deviations of 0.2 mV and 8.9 mV, respectively. The result for the current reference gives a measurement of 23.5 μA, with a maximum deviation of 1.2 μA. The measurements also show that the wireless temperature sensor has good sensitivity of 9.55 mV/°C and high linearity of 97%. The proposed temperature sensor has 4.15-times better sensitivity than the previous design. Moreover, to facilitate temperature data collection, standard wireless data transmission is chosen; therefore, an 8-bit successive-approximation-register (SAR) analog-to-digital converter (ADC) and a 433 MHz wireless transmitter are also integrated in this chip. Sensing data from different places can be collected remotely avoiding the need for complex wire lines.

Implementation of SOPC based Telecom & Datacom for monitoring wireless sensor networks

In this paper, we used SOPC to develop WSN Control Center to be monitored by Telecom and Datacom. We design the Wireless/Wired Board to receive sensing data from wireless sensor network and through DM9000A Ethernet to provide network monitor over Internet. Especially, WSN Control Center use GSM/GPRS modem to do the emergency reports by Telecom. In the software Design, we programming and immigrating of uClinux Kernel 2.6 OS and the developing of CC1100 WSN application, the system can control and transmit sensing data in the wireless sensor network. This module can be established in communication protocol of the wireless temperature sensors. The data is interpreted by the uClinux OS will appear on the screen and Seven-segment Display; moreover, this system can be applied to the output seven segment LED, and through the connection of Ethernet. Our architecture provides a high degree of scalability and flexibility. It can connect to the Internet, so as to collect the sensor data in the SOPC embedded system, and it can be accessed at anywhere in the world.

Powering a wireless temperature sensor using sediment microbial fuel cells with vertical arrangement of electrodes

The application of wireless sensors is an important approach for monitoring natural water systems in remote locations; however, limited power sources are a key challenge for successful application of these sensors. Sediment microbial fuel cells (SMFCs) have shown potential as a sustainable power source with low maintenance requirements to power wireless sensors. This study examines electricity generation in lab-scale SMFCs with the sediment from Lake Michigan. Two SMFCs are operated in parallel with a difference in cathode arrangement (floating cathode vs. bottom cathode). The data show that the SMFC with a floating cathode produces more electricity and results in a shorter charging time when an ultracapacitor is connected to the circuit. To control electricity delivery and voltage elevation to a value that can drive a wireless temperature sensor, a power management system (PMS) is developed. With the PMS, both SMFCs can consistently power the wireless temperature sensor for data transmission to a computer, although the number of recorded data within the same period differs. This research provides an effective PMS for power control and valuable experience in SMFC configurations for the next onsite test of the developed SMFCs in Lake Michigan.

A wind-flutter energy converter for powering wireless sensors

This paper describes a low-speed wind energy harvesting system that transfers aerodynamically induced flutter energy into electrical energy. A random airflow generates mechanical vibrations due to the fluid–structure interaction between a flexible belt and the airflow. An electromagnetic resonator with copper coils and a permanent magnet is designed to efficiently harvest electrical energy from the induced mechanical vibrations. Different groups of springs are compared at various wind conditions to maximize the power output. Typically ∼7 mW of electrical energy can be obtained at ∼3 m/s wind speed with a 1 m long belt. A power conditioning circuit with a charge pump and a DC–DC converter is used to convert the generated voltage into a stable 3.3 V DC for consumption. It is demonstrated that this generator can be used to drive a commercial wireless temperature sensor.

Design of Measure Control System for Thermal Defects Based on ZigBee

To measure and control thermal defects of power station, continuous power is provided to the ZigBee wireless temperature sensors by using monocrystalline silicon solar cells and thermoelectric generation modules, which can collect and process the real-time temperatures of high voltage equipments in the station. Simultaneity, the system can solve the problem that overheat faults can not alarm timely when efficiency of solar cell decreases during the continuous rainy days. The remote real-time controlling is realized by using client and server programs of VC + +.NET. The lossless compression and real-time image transmission are implemented through employing the screen grid-division method and the Huffman compression algorithm. All of these provide a technical assurance to the remote controlling of heat vice of high-voltage equipments in multi-stations.

A wireless inductive-capacitive (L-C) sensor for rotating component temperature monitoring

Abstract Temperature monitoring is critical in almost every type of machinery and application, especially in rotating components such as jet turbines, engines, and power plants, etc. These components involve harsh environments and where the physical connections for monitoring systems are impossible. This paper presents a resonant inductive-capacitive (L-C) circuit based wireless temperature sensor suitable for working in these harsh environments to monitor the temperature of rotating components. Design and performance analysis of the wireless temperature sensor has been conducted and the sensor prototype was successfully fabricated and calibrated up to 200°C with sensitivity of 30 kHz/°C. As a result it is confirmed that temperature monitoring of a rotating component can be carried out without requiring physical connection, power supplies or active elements in the sensor circuit.

High temperature interrogation unit for wireless SAW-based temperature sensors

Surface acoustic waves (SAW) have been studied for more than 50 years and are mainly used as frequency filters. Using appropriate design considerations, these devices are sensitive to external conditions including temperature, pressure, strain or chemical/biological mass loading: hence, SAW sensors are implemented and provide unique characteristics [1]. Amongst the original characteristics, the linear behavior of the piezoelectric substrates provides interrogation ranges hardly achieved with silicon-based radiofrequency devices, extreme working temperatures and simple manufacturing conditions with a single cleanroom process step: hence, SAW transducers provide ideal transducers for passive sensors interrogated through a radiofrequency wireless link. This work is devoted to the development of a wireless interrogation system able to operate under high temperature environments (650 to 900°C for the sensors). As wireless passive SAW-based sensors are considered here, the sensor reading allows the interrogation unit (so-called reader) to be far enough (some meters) to avoid facing such temperature conditions. However, the reader must be able to operate at temperatures in the 100-150°C range, beyond the usual industrial grade integrated circuit characteristics. Therefore, the capability of the reader to operate under such conditions and hence to meet the above specifications is considered. The sensor and the interrogation unit are here both submitted to “high” temperature environments, with different meaning whether passive surface acoustic wave (SAW) sensors or reader including CMOS and radio-frequency (RF) components are considered. We qualify the maximum operating temperature of our reader designed using commercial off the shelf (COTS) components with standard temperature requirements. The reader is tested from room temperature up to failure, which is met around 140°C. The cause of the failure is due to a communication chip (RS232-USB converter): the whole interrogation unit is thus expected to reach even higher temperatures without significant performance losses.

Wireless Temperature Sensing with BST-Based Chipless Transponder Utilizing a Passive Phase Modulation Scheme

A passive wireless temperature sensor with identification capabilities based on a phase modulation scheme is discussed in this paper. The approach presented utilizes a pulse backscatter technique based on slow wave (metamaterial) transmission lines. The focus of the work are the material engineering for the temperature-sensitive element and the integration of this element into a passive phase modulation circuit and the entire sensor tag. The approach makes use of temperature-sensitive bariumstrontium-titanate thick film capacitances. The discussed principle has been experimentally verified with a prototype.