Temperature Microsensors Research Articles

Ultrasensitive, Fast-Response, and Stretchable Temperature Microsensor Based on a Stable Encapsulated Organohydrogel Film for Wearable Applications.

Ionic conductive hydrogel-based temperature sensors have emerged as promising candidates due to their good stretchability and biocompatibility. However, the unsatisfactory sensitivity, sluggish response/recovery speed, and poor environmental stability limit their applications for accurate long-term health monitoring and robot perception, especially in extreme environments. To address these concerns, here, the stretchable temperature sensors based on a double-side elastomer-encapsulated thin-film organohydrogel (DETO) architecture are proposed with impressive performance. It is found that the water-polyol binary solvent, organohydrogel film, and sandwiched device structure play important roles in the temperature sensing performance. By modifying the composition of binary solvent and thicknesses of organohydrogel and elastomer films, the DETO microsensors realize a thickness of only 380 μm, unprecedented temperature sensitivity (37.96%/°C), fast response time (6.01 s) and recovery time (10.53 s), wide detection range (25-95.7 °C), and good stretchability (40% strain), which are superior to those of conventional hydrogel-based sensors. Furthermore, the device displays good environmental stability with negligible dehydration and prolonged operation duration. With these attributes, the wearable sensor is exploited for the real-time monitoring of various physiological signals such as human skin temperature and respiration patterns as well as temperature perception for robots.

An Integrated Micro-Heating System for On-Chip Isothermal Amplification of African Swine Fever Virus Genes.

The loop-mediated isothermal amplification (LAMP) is widely used in the laboratory to facilitate rapid DNA or RNA detection with a streamlined operational process, whose properties are greatly dependent on the uniformity and rise rate of temperature in the reaction chambers and the design of the primers. This paper introduces a planar micro-heater equipped with an embedded micro-temperature sensor to realize temperature tunability at a low energy cost. Moreover, a control system, based on the Wheatstone bridge and proportional, integral, and derivative (PID) control, is designed to measure and adjust the temperature of the micro-heater. The maximum temperature rise rate of the designed micro-heater is ≈8°Cs-1, and it only takes ≈60s to reach the target temperature. Furthermore, a designed plasmid, containing the B646L gene of African Swine Fever Virus (ASFV), and a set of specific primers, are used to combine with the designed micro-heating system to implement the LAMP reaction. Finally, the lateral flow assay is used to interpret the amplification results visually. This method can achieve highly sensitive and efficient detection of ASFV within 40min. The sensitivity of this on-chip gene detection method is 8.4 copies per reaction, holding great potential for applications in DNA and RNA amplification.

Internet of Things-Enabled Patch With Built-in Microsensors and Wireless Chip: Real-Time Remote Monitoring of Patch Treatment.

We aimed to design, develop, and evaluate an internet of things-enabled patch (IoT patch) for real-time remote monitoring of adherence (or patch wear time) during patch treatment in child participants in clinical trials. This study provides healthcare providers with a tool for objective, real-time, and remote assessment of adherence and for making required adjustments to treatment plans. The IoT patch had two temperature microsensors and a wireless chip. One sensor was placed closer to the skin than the other, resulting in a temperature difference depending on whether the patch was worn. When the patch was worn, it measured temperatures every 30 seconds and transmitted temperature data to a cloud server via a mobile application every 15 seconds. The patch was evaluated via 2 experiments with 30 healthy adults and 40 children with amblyopia. Excellent monitoring accuracy was observed in both adults (mean delay of recorded time data, 0.4 minutes) and children (mean, 0.5 minutes). The difference between manually recorded and objectively recorded patch wear times showed good agreement in both groups. Experiment 1 showed accurate monitoring over a wide range of temperatures (from 0 to 30°C). Experiment 2 showed no significant differences in wearability (ease-of-use and comfort scores) between the IoT and conventional patches. The IoT patch offers an accurate, real-time, and remote system to monitor adherence to patch treatment. The patch is comfortable and easy to use. The utilization of an IoT patch may increase adherence to patch treatment based on accurate monitoring. Results show that the IoT patch can enable real-time adherence monitoring in clinical trials, improving treatment precision, and patient compliance to enhance outcomes.

Development of a new intelligent instrument for visibility and turbulence meteorological environment parameters in traffic network

The number of transport network systems in the world is increasing and the transport network passes through different geographical environments, there is an urgent need to develop an environmental meteorological monitoring equipment for the transport network security. So, in this study, a new intelligent instrument for monitoring the visibility and turbulence meteorological environmental parameters (temperature, pressure, humidity, etc.) of traffic networks (IVMPT) is developed. The feasibility of simultaneous measurement of visibility, turbulence and various meteorological elements is verified. The atmospheric visibility is measured based on the extinction principle and the atmospheric turbulence in a certain range based on the light intensity scattering principle. The commercial Visibility instrument (DNQ2-1) and Micro-temperature Sensor are used to compare with our new instrument. The results show that the difference between the visibility and turbulence measurements and the comparison instrument is 3% and 8.4%, respectively. After comparative examination, the new instrument meets the design requirements. In addition to environmental meteorological monitoring applications in the transport network, the instrument provides a new scientific instrument for the study of aerosol-turbulence interactions in basic science issues.

Flexible Pressure and Temperature Microsensors for Textile-Integrated Wearables

Environmental factors, such as pressure and temperature, are known to contribute to the formation of ulcers that seriously affect bedridden individuals. Researchers have proposed several technologies to achieve the long-term monitoring of those parameters, usually relying on sensing mats, which poses difficulties in correlating the measurements with specific parts of the body. In this work, we aim to develop microsensors to be integrated into patient clothing. They should be highly flexible, thin with a small footprint, and can be achieved by taking advantage of the microfabrication on polyimide (PI) thin-film substrates (total device thicknesses below 30 µm). Both resistive and capacitance transduction mechanisms were explored, targeting operation ranges of 1 to 40 kPa and 24 to 42 °C. The sensors were integrated into textiles using silicone elastomers and electrical connections based on conductive silver yarn. The experimental characterization showed a nominal capacitance of 21 pF, a sensitivity of −8.44 fF/kPa for the pressure sensors, and a 0.0021 Ω/Ω°C sensitivity of the temperature sensor (with resistance of 29 kΩ at 22 °C). The proposed approach can potentially be implemented not only in wearable devices but also in many other applications for health monitoring or human–machine interfaces.

A pressure- temperature microsensor based on synergistical sensing of dual resonators

Simultaneous measurements of pressure and temperature take wide attentions for several technical applications. This pressure–temperature microsensor fully utilizes the mechanical and thermal features of common semiconductor materials which can be achieved by micro-electro mechanical technologies, in contrast to typical simultaneous measurement systems that rely on optical properties of fiber materials. The idea is illustrated using two identical resonators that work synergistically to sense the pressure and temperature. The pressure and temperature sensing are determined by the reactions of pressure sensitive diaphragm to pressure and the differences in the coefficients of thermal expansion among the composed materials of the microsensor, respectively. The pressure and temperature sensitivity of the dual resonators in this work were calculated by numerical simulations and verified by experimental characterizations. Additional characterizations revealed that the measurement pressure and temperature errors of the developed microsensor were within −10 Pa to 40 Pa and −0.25℃ to 0.26℃ with corresponding accuracy of ± 0.01 %FS (Full scale) and ± 0.2 %FS, respectively.

Fabrication of high-frequency microfluidic oscillators with integrated thermal instrumentation

Fluidic devices were once a staple of control systems in harsh environments such as nuclear power plants or satellites, until they were superseded by electronic systems whose performance and size were rapidly improving. Nevertheless, the simplicity, robustness and autonomy of fluidic devices remain attractive features in many fluids engineering applications. In this study, a microfluidic oscillator, with a main jet only 20μm wide, is produced, instrumented and tested. Particular to this study is the use of temperature micro-sensors that were embedded inside the oscillator in order to perform non-intrusive measurements. In addition, air is used as a working fluid and is fed at high pressures so that the flow is choked at the inlet. The pulsation of the oscillators can reach frequencies of up to 9kHz and it was possible to measure the resulting fluctuations at different points inside the micro-channels. The sensors were able to detect harmonics at up to 50kHz. With this spatial and temporal information, it finally becomes possible to probe the inner dynamics of the micro-meter scale oscillator and to better understand phenomena such as high-frequency microjet switching under highly compressible flow conditions.

The effectiveness of motivational interviewing on adherence to wearing orthopedic shoes in people with diabetes at low-to-high risk of foot ulceration: A multicenter cluster-randomized controlled trial

AimTo evaluate the effectiveness of motivational interviewing (MI) performed by MI-trained podiatrists in improving adherence to wearing orthopedic shoes in comparison to usual care in people with diabetes at low-to-high risk of ulceration. MethodsPeople with diabetes with loss of protective sensation and/or peripheral artery disease, and with orthopedic shoes prescription were allocated to receive one MI-consultation by a podiatrist randomized to MI training (n = 53) or usual care only (n = 68). Adherence was measured as the percentage of steps taken while wearing orthopedic shoes, determined using an insole temperature microsensor and wrist-worn activity tracker during one week at 3 and 6 months. ResultsThe proportion of participants ≥80 % adherent to wearing their orthopedic shoes was higher in the control group than in the MI-intervention group at 3 months (30.9 % versus 15.1 %; p = 0.044), and not significantly different at 6 months (22.1 % versus 13.2 %; p = 0.210). Average adherence was also higher in the control group than the intervention group at both 3 months (60.9 % versus 50.9 %; p = 0.029) and 6 months (59.9 % versus 49.5 %; p = 0.025). ConclusionsOne podiatrist-led MI-consultation in its current form did not result in higher adherence to wearing orthopedic shoes in people with diabetes 3 and 6 months after inclusion.Trial registration: Netherlands Trial Register NL7710 (available on the International Clinical Trials Registry Platform).

Comprehensive Numerical Analysis of Temperature Sensitivity of Spherical Microresonators Based on Silica and Soft Glasses

In recent years, the use of optical methods for temperature measurements has been attracting increased attention. High-performance miniature sensors can be based on glass microspheres with whispering gallery modes (WGMs), as their resonant frequencies shift in response to the ambient parameter variations. In this work, we present a systematic comprehensive numerical analysis of temperature microsensors with a realistic design based on standard silica fibers, as well as commercially available special soft glass fibers (GeO2, tellurite, As2S3, and As2Se3). Possible experimental implementation and some practical recommendations are discussed in detail. We developed a realistic numerical model that takes into account the spectral and temperature dependence of basic glass characteristics in a wide parameter range. To the best of our knowledge, spherical temperature microsensors based on the majority of the considered glass fibers have been investigated for the first time. The highest sensitivity dλ/dT was obtained for the chalcogenide As2Se3 and As2S3 microspheres: for measurements at room temperature conditions at a wavelength of λ = 1.55 μm, it was as high as 57 pm/K and 36 pm/K, correspondingly, which is several times larger than for common silica glass (9.4 pm/K). Importantly, dλ/dT was almost independent of microresonator size, WGM polarization and structure; this is a practically crucial feature showing the robustness of the sensing devices of the proposed design.

Integrated interdigital electrode and thermal resistance micro-sensors for electric vehicle battery coolant conductivity high-precision measurement

Monitoring the conductivity of battery coolant is extremely important as it can significantly improve the safety of electric vehicles. The conductivity of coolant should be maintained in the range of 0-10 μS/cm to ensure the insulation level, requiring high-precision measurement of ultra-low detection range. However, polarization and capacitive effects, temperature effects, as well as poor stability, all pose significant challenges to achieving high-precision conductivity measurements. This work describes a novel integrated conductivity and temperature (CT) micro-sensor for the conductivity high-precision measurement of electric vehicle battery coolant. An interdigital micro-electrode is fabricated for conductivity sensing and a thin-film platinum resistor is employed as temperature sensor cell. The integrated CT sensor demonstrates an acceptable limit of detection with a resolution of 0.1 μS/cm. Besides, high-precision signal acquisition and processing circuit is designed for sensors and a desirable measuring full-scale error is observed. Compared to the current method of using bulky metal electrodes prepared by mechanical process as conductivity sensor, the proposed sensor can be mass produced by Micro-Electro-Mechanical System (MEMS), and favorable consistency, high sensitivity, excellent stability, smaller size are obtained. Consequently, the as-proposed CT micro-sensor has an opportunity to be developed as a competitive device for online conductivity monitoring in battery coolant.

Microfluidic Construction of Responsive Photonic Microcapsules of Cholesteric Liquid Crystal for Colorimetric Temperature Microsensors

AbstractAs alternatives to electronic devices, optically active structures from responsive nanomaterials offer great opportunity for building up smart functional sensors. This work reports on the construction and application of photonic microcapsules (PMCs) for colorimetric temperature microsensors, enabling miniaturization for injectable local micro‐area sensing and integration for large‐area sensing. Monodispersed PMCs are produced by in situ photopolymerization of hydrogel shells of cholesteric liquid crystal (CLC)‐in‐water‐in‐oil double emulsion droplets prepared using microfluidic devices, with controllable physical structures and chemical compositions. Constructed PMCs exhibit thermal responsive structural color according to the selective Bragg reflection of CLC's periodical helical structures within the microdroplet's spherical confinement. CLC mixtures with phase transition temperature of 56.0 and 37.8 °C have been prepared and employed to construct PMCs exhibiting obviously visible and quantifiable optical response in 52–56 and 33–38 °C, respectively. The PMCs have been successfully applied for monitoring the living cell extracellular temperature via co‐incubation with cell suspension, and for sensing human forehead temperature via a flexible device from assembled PMCs. These PMCs can be flexibly applied in either micro‐environment or large‐area surface, enabling wide applications for a precision temperature monitoring of biological activities (e.g., cells or organs), optoelectronic devices working conditions (e.g., temperature indicators under extreme conditions), etc.

Evaluating the concept of gas‑based intraperitoneal hyperthermia beyond 43˚C in the treatment of peritoneal metastasis: A pilot study.

While hyperthermic intraperitoneal applications have demonstrated high efficacy in treating peritoneal metastases (PM), these applications are limited to temperatures of 41-43˚C to prevent a harmful increase in core temperature. However, since gaseous substances display low specific heat capacities, gas-based hyperthermia could potentially increase surface temperatures without affecting the body's core temperature. To the best of our knowledge, the present study is the first to explore the in vivo feasibility of gas-based hyperthermia via spatial and time-based distribution. In the present study, a temperature-isolated, abdominal box model was created with fresh peritoneal tissue exposed to continuous high-volume airflow temperatures ranging between 47 and 69˚C. Heat conduction within the peritoneal tissues was measured using temperature microsensors. Temperature build-up at different time points during the procedure was calculated and the safest option to perform gas-based intraperitoneal hyperthermia beyond 43˚C was identified using an in vivo swine model. In subsequent experiments, viability and cytotoxicity of HT-29 colon cancer cells were measured following short-term hyperthermia. The present study demonstrated that the application of gas-based intraperitoneal hyperthermia with temperatures up to 50˚C is possible without increasing the core temperature to harmful levels. Gas-based intraperitoneal hyperthermia can induce a histological reaction on the peritoneal surface, and it can also result in decreased viability and increased cytotoxicity of HT-29 cells. The concept of extreme hyperthermia may be of great clinical importance as it could significantly increase local cytotoxicity in PM without increasing the body's core temperature. Further studies are required to investigate the benefits, as well as the restrictions, of this novel concept.

Real-Time Micro-Monitoring of Surface Temperature and Strain of Magnesium Hydrogen Tank through Self-Made Two-In-One Flexible High-Temperature Micro-Sensor.

The adsorption and desorption of hydrogen in the magnesium powder hydrogen tank should take place in an environment with a temperature higher than 250 °C. High temperature and high strain will lead to reactive hydrogen leakage from the magnesium hydrogen tank due to tank rupture. Therefore, it is very important to monitor in real time the volume expansion, temperature change, and strain change on the surface of the magnesium hydrogen tank. In this study, the micro-electro-mechanical systems (MEMS) technology was used to innovatively integrate the micro-temperature sensor and the micro-strain sensor into a two-in-one flexible high-temperature micro-sensor with a small size and high sensitivity. It can be placed on the surface of the magnesium hydrogen tank for real-time micro-monitoring of the effect of hydrogen pressure and powder hydrogen absorption expansion on the strain of the hydrogen storage tank.

Application of Monitoring Module Three-in-One Microsensor to Real-Time Microscopic Monitoring of Polarizer Sheet in Roll-to-Roll Process

The Roll-to-Roll (R2R) process refers to a high-efficiency, low-cost, continuous production method. The roll material used for processing is a flexible plastic or metal film. In many R2R processes, polarizing films are high-precision products with a high output value. In the production of conventional polarizers, product inspection will only be carried out after the production of the polarizing film is completed. The principal raw material of a polarizer sheet is a hydrophilic polymer, the properties of which may be influenced by water vapor, which degrades its quality. Whether or not the product is impacted can be ascertained by means of a quality inspection, but it must be performed after the process is finished. However, it is already too late when a defective product is detected: the production cost is increased, the schedule is influenced and the delivery date is delayed. The focus of this research was on environmental monitoring of the production drying process oven, but the commercial all-in-one sensors currently on the market cannot tolerate the temperature of the factory’s high-temperature oven. In particular, a commercial flow sensor is rarely suited to high-temperature applications. Some are expensive and cannot be widely distributed. Therefore, this study aimed to develop an integrated sensor to measure the internal environment of the drying process oven for the real-time monitoring of a polarizer sheet in the Roll-to-Roll (R2R) process. This study used micro-electro-mechanical systems (MEMS) technology to make a flexible three-in-one (temperature, humidity and flow) micro-sensor. We monitored the temperature, humidity and flow uniformity in a laboratory oven to simulate the environment of the actual factory oven, with the aim to provide data to confirm whether or not a polarizer sheet has dried. Our system can be monitored instantly by Arduino, or even Raspberry Pi 3, to realize the flexible micro-sensor layout and field verification, in order to optimize the R2R process and to enhance the yield and performance of the polarizer sheet process.

Real-time microscopic monitoring of temperature and strain on the surface of magnesium hydrogen storage tank by high temperature resistant flexible integrated microsensor

Magnesium hydrogen storage tanks shrink and expand due to different states of hydrogen absorption and desorption, so it is important to monitor the body expansion, temperature change and stress change on the surface of magnesium hydrogen storage tank in real time. At present, commercially available temperature sensors and strain gauges are bulky, and the two sensors are not easy to be placed on the surface of magnesium hydrogen storage tanks for accurate measurement. Therefore, this study used micro-electromechanical systems (MEMS) technology to innovate and integrate micro-temperature sensor and micro-strain sensor, and make a small volume but high sensitivity high temperature resistant flexible integrated microsensor, which can be placed on the surface of the magnesium hydrogen storage tank to monitor the temperature, expansion and stress changes in real time, thus providing a reference for improving the optimal design of the magnesium hydrogen storage tank.

Using motivational interviewing combined with digital shoe-fitting to improve adherence to wearing orthopedic shoes in people with diabetes at risk of foot ulceration: study protocol for a cluster-randomized controlled trial

BackgroundDiabetic foot ulcers have a high impact on mobility and daily functioning and lead to high treatment costs, for example, by hospitalization and amputation. To prevent (re)ulcerations, custom-made orthopedic shoes are considered essential. However, adherence to wearing the orthopedic shoes is low, and improving adherence was not successful in the past. We propose a novel care approach that combines motivational interviewing (MI) with a digital shoe-fitting procedure to improve adherence to orthopedic shoes. The aim of this trial is to assess the (cost-)effectiveness of this novel care approach compared to usual care (no MI and casting-based shoe-fitting) in promoting footwear adherence and ulcer prevention.MethodsThe trial will include people with diabetes, with IWGDF Risk categories 1–3, who have been prescribed orthopedic shoes. Participants will be randomized at the level of the podiatrist to the novel care approach or usual care. The primary outcome is the proportion of participants who adhere to the use of their orthopedic shoes, that is, who take at least 80% of their total daily steps with orthopedic shoes. A temperature microsensor will be built into the participants’ orthopedic shoes to measure wearing time continuously over 12 months. In addition, daily activity will be measured periodically using log data with an activity monitor. Data from the temperature microsensor and activity monitor will be combined to calculate adherence. (Re-)experienced complications after receiving orthopedic shoes will be registered. Questionnaires and interviews will measure the experiences of participants regarding orthopedic shoes, experiences of podiatrists regarding motivational interviewing, care consumption, and quality of life. Differences in costs and quality of life will be determined in a cost-effectiveness analysis.DiscussionThis trial will generate novel insights into the socio-economic and well-being impact and the clinical effectiveness of the novel care approach on adherence to wearing orthopedic shoes.Trial registrationNetherlands Trial Register NL7710. Registered on 6 May 2019

Flexible 6-in-1 Microsensor for Real-Time Microscopic Monitoring of Proton Battery.

According to the comparison between a proton battery and a proton exchange membrane fuel cell (PEMFC), the PEMFC requires oxygen and hydrogen for generating electricity, so a hydrogen tank is required, leading to larger volume of PEMFC. The proton battery can store hydrogen in the carbon layer, combined with the oxygen in the air to form water to generate electricity; thus, the battery cost and the space for a hydrogen tank can be reduced a lot, and it is used more extensively. As the proton battery is a new research area, multiple important physical quantities inside the proton battery should be further understood and monitored so as to enhance the performance of battery. The proton battery has the potential for practical applications, as well as water electrolysis, proton storage and discharge functions, and it can be produced without expensive metals. Therefore, in this study, we use micro-electro-mechanical systems (MEMS) technology to develop a diagnostic tool for the proton battery based on the developed microhydrogen sensor, integrated with the voltage, current, temperature, humidity and flow microsensors developed by this laboratory to complete a flexible integrated 6-in-1 microsensor, which is embedded in the proton battery to measure internal important physical parameters simultaneously so that the reaction condition in the proton battery can be mastered more accurately. In addition, the interaction of physical quantities of the proton battery are discussed so as to enhance the proton battery’s performance.

Development of Highly Sensitive Temperature Microsensors for Localized Measurements

This paper presents the design, fabrication and characterization of temperature microsensors based on Resistance Temperature Detectors (RTDs) with a meander-shaped geometry. Numerical simulations were performed for studying the sensitivity of the RTDs according to their windings numbers as well as for optimizing their layout. These RTDs were fabricated using well-established microfabrication and photolithographic techniques. The fabricated sensors feature high sensitivity (0.3542 mV/°C), linearity and reproducibility in a temperature range of 35 to 45 °C. Additionally, each sensor has a small size with a strong potential for their integration in microfluidic devices, as organ-on-a-chip, allowing the possibility for in-situ monitoring the physiochemical properties of the cellular microenvironment.

Recent advances in generalized thermoelasticity theory and the modified models: a review

Abstract A review of the recent studies on the generalized thermoelasticity theories and their associated modified models is presented. The aim is to outline an overview of the utilization and physical limitations of available relevant theories. By contrast to classical thermoelasticity theory, generalized thermoelasticity theories (second sound) can involve a hyperbolic-form transport correlation and are motivated by experiments illustrating more accurately of the wave-form heat transfer (second sound). Many researchers have formulated such theories on different fields and analyzed various problems, presenting characteristic properties of these theories. This paper expresses a self-included bibliographical review of previous documents in the area of the second sound. The general structure of this review contains theories, formulations, real limitations, and used solution techniques of the equations for different geometries and loadings. Given that the classical theory is feeble in simulating the temperature distribution, especially in the structures under a sudden thermal shock, this review may be a useful tool for researchers who work in sensitive industries such as steam turbines, micro-temperature sensors, and lithium battery manufacturing.

What Do We Know About Adherence to Oral Appliances?

Long-term effective therapy is essential for obstructive sleep apnea (OSA) control and preventing comorbidity. OSA patients are often reported to be more receptive to oral appliance therapy over positive airway pressure (PAP). Oral appliance usage can now be objectively recorded by temperature microsensors. Studies using commercially available microsensor chips have reported data out to 1year, with high rates of adherence (>80%), albeit in small samples. There is opportunity to further use this technology to understand individual adherence factors and patterns and in obtaining objective measures of treatment effectiveness, particularly for longer-term health outcomes and allowing comparison to PAP.