MEMS Temperature Sensor Research Articles

Epitaxial Polysilicon MEMS Temperature Sensor With 0.043 °C Resolution at 4-Hz Data Rate

Epitaxial Polysilicon MEMS Temperature Sensor With 0.043 °C Resolution at 4-Hz Data Rate

Performance Improvement of Integrated MEMS Temperature, Humidity, and Air Velocity Sensors for Application in Smart Buildings

Performance Improvement of Integrated MEMS Temperature, Humidity, and Air Velocity Sensors for Application in Smart Buildings

A Wide-Dynamic Range (-40 °C to 180 °C) Active Wireless MEMS Temperature Sensor With 7m °C Sensitivity

We demonstrate a highly-accurate active wireless microelectromechanical (MEMS) temperature sensor with the largest reported dynamic range (-40°C to 180°C) among active MEMS temperature sensors. The sensor uses a 27.2 MHz high quality factor (Q > 3,200) AlN-on-Si thin-film piezoelectric-on-silicon (TPoS) MEMS resonator to enable highly accurate temperature sensing, with minimum sensitivity (S), better than 0.011 °C across this wide temperature range. The wireless sensor uses an innovative frequency shift keying (FSK) 900 MHz direct up-conversion transmitter. The transmitter uses frequency multipliers for up-conversion, obviating the need for a temperature-stable frequency reference clock, thereby preserving the temperature coefficient of frequency (TCF) of the resonator, and consequently the sensitivity of the sensor. The experimental results show a very high correlation (<0.03% error) between the TCF of the MEMS oscillator and that of the transmitter output signal, demonstrating the viability of the proposed direct up-conversion technique. A detailed analysis of the Allan variance for MEMS temperature sensors which can be used to design for a given minimum sensitivity, is also presented in the paper.

Protecting COVID-19 Vaccine Transportation and Storage from Analog Cybersecurity Threats

Protecting COVID-19 Vaccine Transportation and Storage from Analog Cybersecurity Threats

Study of the Photo- and Thermoactivation Mechanisms in Nanoscale SOI Modulator

A new nanoscale silicon-based modulator has been investigated at different temperatures. In addition to these two advantages, nanoscale dimensions (versus MEMS temperature sensors) and integrated silicon-based material (versus polymers), the third novelty of such optoelectronic device is that it can be activated as a Silicon-On-Insulator Photoactivated Modulator (SOIPAM) or as a Silicon-On-Insulator Thermoactivated Modulator (SOITAM). In this work, static and time dependent temperature effects on the current have been investigated. The aim of the time dependent temperature simulation was to set a temporal pulse and to check, for given dimensions, how much time would it take for the temperature profile and for the change in the electrons’ concentration to come back to the steady state. Assuring that the thermal response is fast enough, the device can be operated as a modulator via thermal stimulation or, on the other hand, can be used as thermal sensor/imager. We present here the design, simulation, and model of the second generation which seems capable of speeding up the processing capabilities. This novel device can serve as a building block towards the development of optical/thermal data processing while breaking through the way to all optic processors based on silicon chips that are fabricated via typical microelectronics fabrication process.

Design and fabrication of a high performance resonant MEMS temperature sensor

This paper presents a high performance MEMS temperature sensor comprised of a double-ended-tuning-fork (DETF) resonator and strain-amplifying beam structure. The temperature detection is based on the ‘thermal strain induced frequency variations’ of the DETF resonator. The major source of thermal strain leading to the frequency shifts is the difference in thermal expansion coefficients of the substrate and the device layers of the fabricated structures. By selecting the substrate as glass and the device layers as single crystal silicon, i.e. materials with different thermal expansion coefficients, the tines of the resonators are exposed to axial load with the changing temperature, which causes a change in the resonance frequency of the resonators. This resonance frequency shift can be related with the changing temperature by taking the thermal strain relations into consideration, which enables utilization of the resonator as a highly sensitive temperature sensor. The resonators used in this study have been fabricated by utilizing the advanced MEMS process that incorporates the simple silicon-on-glass process with the wafer level vacuum packaging Torunbalci et al (2015 J. Microelectromech. Syst. 24 556–64). The fabricated resonators have been tested in a temperature-controlled oven between −20 °C and 60 °C, and the results of two distinct designs are compared to be able to observe the effectiveness of the strain amplifying beam. Measurement results show that the design with the strain amplifying beam increases the temperature coefficient of frequency of the resonators by 33 times when compared to the one-end free DETF resonators. Minimum detectable temperature variations observed by the resonators used in this study is 0.0011 °C. This kind of very high resolution temperature sensing can be achieved by integrating this MEMS temperature sensor with any type of physical MEMS sensor where its fabrication process includes different materials for the substrate and sensor structures.

Interactions of Adhesion Materials and Annealing Environment on Resistance and Stability of MEMS Platinum Heaters and Temperature Sensors

We evaluate the microstructural and electrical stability of Pt thin films with Ti or Ta as the adhesion layer after furnace annealing and rapid thermal annealing up to 750°C in three different environments. Test devices were made with 100 nm of Pt with a 10-nm adhesion layer. After annealing, the resistance anomalously increased for samples annealed in ultrahigh purity N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (UHP, 99.999%), while the resistance decreased, as expected, for samples annealed in 99.95% N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> or air. The Ta/Pt film stack shows better microstructural and electrical stability compared with Ti/Pt. X-ray photoelectron spectroscopy (XPS) data indicate that diffusion of the Ti and Ta adhesion layers through the Pt film occurs in samples annealed in UHP N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , which is responsible for the remarkable increase of resistance. For samples annealed in air, the oxidation of Ti/Ta suppresses the diffusion process and expected grain growth occurs in the Pt, thus decreasing the resistance. Furthermore, XPS elemental mapping and atomic force microscope imaging shed light on void formation/dewetting seen under certain conditions.

Rapid Temperature Measurement of Meteorological Detection System Based on MEMS

This paper is based on a meteorological detection system, which contains MEMS barometric pressure sensors, MEMS temperature sensors, MEMS humidity sensors and GPS receiver. The micro control unit of this system is based on C8051F120 microcontroller. By Comparing SHTXX series of temperature and humidity sensor and PT100 thermal resistance, we obtain a measurement scheme that can measure environment temperature rapidly and relatively accurate when the volume, weight and power are limited. It can meet the harsh environments and high reliable needs. In addition, the simulation analysis and the experiment of temperature are carried out.

Design of Intelligent Meteorological System Based on MEMS

Intelligent weather station system based on MEMS sensors is designed. The automatic meteorological system includes a MEMS temperature sensor, MEMS humidity sensor, MEMS pressure sensor, MEMS wind speed sensor and the sensor intelligent control system, etc. The intelligent control system has functions such as precise timing, multiple sensor data automatic acquisition, storage and uploading, which realizes the intelligent control of this weather station system.

Heat Transfer-Fluid Coupled Simulation for Smart Meteorological Microsystems

The Smart Meteorological Microsystems (SMM) is a kind of microsystems for meteorological information acquisition. SMM consists of two MEMS temperature and humidity sensors, a shell, a micro processor, a communication module, a GPS module, two pressure sensors and their peripheral circuits. The shell is built for protecting the sensors from being damaged when the sensors working in the harsh environment. However the shell also prevents the heat from transferring, leading to the appearance of temperature difference between the areas inside and outside the shell. The environment factors can lead to some temperature measurement errors. In order to solve these problems, this paper has designed an innovative structure of SMM shell. To improve the accuracy of temperature measurement, this paper has analyzed the heat transfer-fluid coupled simulations of temperature field in SMM under the working condition by using COMSOL Multiphysics. According to the results of the simulations, the structure of the SMM shell has been optimized. Either the structure or analysis has been reported in neither domestic nor international papers. As a result, what this paper has done is of a great value.

Thermal Analysis and Optimization of MEMS Temperature Sensor for Food Detection

In order to improve the sensitivity of MEMS temperature sensor, this paper proposes an efficient and robust structural optimum design method for the sensor structure. Based on thermal analysis of software ANSYS, the thermal deformation and distribution of temperature field can be obtained clearly. A predictive model for thermal deformation is established using artificial neural network and the sample for neural network model is designed by using orthogonal experimental method. In the model, the structure parameters of sensor are treated as design variables and the objective is to obtain the maximum deformation. Optimization of structure parameters for sensor was conducted by introducing artificial neural network prediction models into genetic algorithm. The results indicate that the optimization method based on artificial neural network and the genetic algorithm is feasible for improve the sensitivity of chemical sensor.

A novel fabrication process of MEMS devices on polyimide flexible substrates

Micro-electro-mechanic-system (MEMS) devices on flexible substrate are important for non-planar and non-rigid surface applications. In this paper, a novel and cost-effective fabrication process for an 8 × 8 MEMS temperature sensor array with a lateral dimension of 2.5 mm × 5.5 mm on a polyimide flexible substrate is developed. A 40 μm thick polyimide substrate is formed on a rigid silicon wafer using as a mechanical carrier throughout the fabrication by four successive spin coating liquid polyimide. The arrayed temperature sensing elements made of 1200 Å sputtered platinum thin film on polyimide substrate show excellent linearity with a temperature coefficient of resistance of 0.0028/°C. The purposed sensor obtains a high sensitivity of 0.781 Ω/°C at 8 mA at constant drive current. Because of the low heat capacity and excellent thermal isolation, the temperature sensing element shows excellent high sensitivity and a fast thermal response. The finished devices are flexible enough to be folded and twisted achieving any desired shape and form. Employing spin-coated liquid polyimide substrate instead of solid polyimide sheet minimizes the thermal cycling as well as improves the production yield. This fabrication technique first introduces the spin-coated PDMS (Polydimethylsiloxane) interlayer between the silicon carrier and the polyimide substrate and makes the polyimide-based devices separate much easier and greatly simplifies the fabrication process with a high production yield. A non-successive two-stage cure procedure for the polyimide precursor is developed to meet low-temperature requirement of the PDMS interlayer. The fabrication procedure developed in this research is compatible with conventional MEMS technology through an optimized integration process. The novel flexible MEMS technology can benefit the development of other new flexible polyimide-based devices.

Highly Adaptive Transducer Interface Circuit for Multiparameter Microsystems

A reconfigurable transducer interface circuit that combines the communication and signal conditioning necessary to link a variety of sensors and actuators to a microsystem controller is reported. The adaptive readout circuitry supports high-resolution signal acquisition from capacitive, resistive, voltage and current mode sensors with programmable control of gain and offset to match sensor range and sensitivity. The chip accommodates sensor self test and self calibration and supports several power management schemes. It provides digital and analog outputs to control actuators and a standard interface to peripheral components. The 2.2times2.2 mm CMOS chip was fabricated in 0.5-mum, 3-metal, 2-poly process, dissipates ~50 muW at 3.3 V in a typical multisensor application utilizing periodic sleep mode, and can read out a wide range of sensors with high sensitivity. A prototype microsystem with a microcontroller and MEMS pressure, humidity, and temperature sensors has been implemented to characterize interface chip performance

The design of ARCTIC: A rotary compressor thermally insulated μcooler

Microscale cooling to date relies largely on passive on-chip cooling in order to move heat from hot spots to alternate sites. Such passive cooling devices include capillary pump loops (CPL), heat pipes, and thermosiphons. Recent developments for active cooling systems include thermal electric coolers (TECs) for heat removal. This paper focuses on the design of an active microscale closed loop cooling system that utilizes the Rankine vapor compression cycle. In this design, a rotary compressor will generate the high pressure required for efficient cooling and will circulate the working fluid to move heat away from chip level hot spots to the ambient. The rotary compressor will leverage technology gained from the rotary engine power system (REPS) program at UC Berkeley, most specifically the 367 mm 3 displacement platform. The advantage of a Wankel (Maillard) compressor is that it provides six compression strokes per revolution rather than a single compression stroke common to other popular compressors such as the rolling piston. The current Wankel compressor design will achieve a theoretical compression ratio of 4.7:1. The ARCTIC (a rotary compressor thermally insulated μcooler) system will be a microscale hybrid system consisting of some microfabricated (or MEMS) components including microchannels, in plane MEMS valves, and MEMS temperature, pressure and flow sensors integrated with mesoscale, traditionally machined steel components, including the compressor itself. The system is designed to remove between 45 W of heat at 1000 rpm using R-134a but the system is easily scaleable through a speed increase or decrease of the compressor. Further, a vapor compression cycle using R-134a operating between 258 and 310 K has a theoretical coefficient of performance (C.O.P.) of approximately 4.6. While this calculation does not include pressure losses, compressor inefficiency, or heat transfer losses, it provides ample room for significant improvement over comparable TECs with C.O.P.s of approximately 0.1–0.2. Finally, a thermal circuit analysis determines that the time constant to achieve refrigeration temperature at the evaporator in 12 s is possible.

TEMPERATURE RESPONSE OF SILICON MEMS CANTILEVERS DURING AND AFTER Nd:YAG LASER IRRADIATION

This article reports a two-dimensional, finite-difference heat transfer model for calculating the transient temperature distribution in a polycrystalline silicon cantilever during and after irradiation by a Nd:YAG laser. Results include the peak surface temperature after irradiation and the uniform temperature increase in the microcantilever following subsequent heat conduction through the thickness. The calculations reveal that the time scale after which the temperature is uniform through the thickness is on the order of hundreds of nanoseconds and that the microcantilever cools in the order of tens of milliseconds. The effects of energy transfer to the environment by convection and radiation on the cooling time are also investigated. The accuracy of the model predictions are shown through high-speed temperature measurements using a novel MEMS temperature sensor.

Autoclave Reliability of MEMS Pressure and Temperature Sensors Embedded in Carbon Fiber Composites

In this paper, embedding of surface mount pressure and temperature sensors in the carbon fiber composites are described. Commercially available surface mount pressure and temperature sensors are used for embedding in a composite lay-up of IM6/HST-7, IM6/3501, and AS4/E7T1-2 prepregs. The fabrication techniques developed here are the focus of this paper. A successful embedding procedure of pressure and temperature sensors in fibrous composites is described in detail. The description includes techniques for positioning and insulating the sensors and the lead wires from the conductive carbon prepregs. Procedural techniques are developed and discussed for isolating the pressure sensor’s flow-opening, from the exposure to the prepreg epoxy flow and exposure to the fibrous particles, during the autoclave curing of the composite laminate. The effects of the autoclave cycle (if any) on the operation of the embedded pressure and temperature sensors are discussed.