Papers by Keyword: Thermopile

Abstract: This work presents a photolithographic rapid prototyping process for producing thin films ("Rapid Phototyping"). This process allows a quick and cost-effective generation of scalable thermopile microstructures using commercial equipment and materials. Structural widths of 100x250μm can be produced reproducible in a lift-off process with an accuracy of 5 microns vertically and 30 microns horizontally.

Abstract: A Cu-Ni thin film heat flux sensor had been fabricated on a 0.05mm thick polyimide film substrate by vacuum coating technology. The overall dimension of the sensor was 8 mm long and 4 mm wide. A thermopile and a thermocouple were arranged on the substrate to measure both heat flux and surface temperature. The thermopile had 18 thermocouple junctions which formed 9 pairs of differential thermocouples and were covered by two different thickness of thermal resistance layers. This research carried out static and dynamic tests of the thin film heat flux sensor. Seebeck coefficient of thermocouple is 19.3761μV/(°C). Sensitivity of the thermopile is 0.010121μV/(W/m²). Steady-state tests of the thermopile and the thermocouple were taken separately. Time constant of the thermocouple is about 0.26s, which is faster than the thermopile of 1.57s.

Abstract: The Seebeck coefficient of heavily-nitrogen-doped n-type polycrystalline 3C-SiC (n-SiC) and platinum (Pt) thin films has been measured from room temperature up to 300 °C by using a microfabricated test structure. At room temperature, the absolute Seebeck coefficient of the n-SiC is -10 μV/°C. With ambient temperature increase, the absolute Seebeck coefficient of the n-SiC is found to gradually increase, reaching -20 μV/°C at 300 °C.

Abstract: The theory of thermal matching of a thermoelectric generator with the environment has been applied in this work to a wearable thermoelectric generator. This enabled evaluation of its top performance characteristics in typical environmental conditions. To correctly perform the modeling, the relevant properties of the human body as a heat generator for a small-size thermoelectric generator have been studied and presented in the paper as well. The results have been practically validated in different wearable thermoelectric generators. In particular, a power over 1 mW per square centimeter of the skin has been practically demonstrated on a walking person at ambient temperature of –2 °C. The comparison with wearable photovoltaic cells shows that in typical situations thermoelectric generators provide at least ten times more power.

Abstract: A new modified infrared tracking sensor array with spatial filter is proposed, which identifies the locations and sizes of thermal object efficiently with the winner-take-all (WTA) circuit and a low offset correlated double sampling (CDS) circuit. The winner-take-all (WTA) circuit is used in combination with active readout circuit for thermopile array. In this circuit, thermal image intensity has been chosen for the input saliency map. The removal process is performed by zeroing the values of the thermal image background intensity levels, so only the potential thermal objects of interest are compared by the WTA. The offset reduction with CDS technique enhances the sensitivity of winner-take-all (WTA) circuit and shows a sharp selectivity which makes it possible to pick up only one winner pixel from each thermal object. In order to simulate and present the infrared thermal sensor array in this paper, the sensor array is integrated by using a 2P4M 0.35μm standard CMOS technology. This proposed architecture shows a high resolution with two orders higher than the circuits without CDS. The results have shown that integrated thermopile array with WTA and CDS can approach a high level of development, reliability and easy for high accuracy infrared tracking applications.

Abstract: A new idea of improving complementary metal-oxide-semiconductor (CMOS) thermopile performance is introduced to reduce the thermal conductance by leading the microcracks into structure of thermopile, which greatly increases the heat flow barrier. A highly sensitive infrared detector requires a low thermal conductance to maximize the temperature change and signal induced by incident IR radiation. Several designs of infrared microsensors are proposed to study influential parameters from microcrack for improving performance of thermopile. To that end, by using some adequate designs of polysilicon architecture, we can greatly reduce the heat flow from the main stream without introducing further electric resistance, which is related with noise. Firstly we develop such a structure of thermopile with low thermal conductance and high performance by using CMOS compatible process which can be easily and exactly fabricated. The suspended structure of infrared sensors is used in this study to provide ideal, thermally isolated, structures for support of the thin film detector. We also simulate the heat flow of the new structures. The results show good match with our original idea.

Abstract: Conventionally the accelerometer behaves like a spring – mass system and its structures involve solid proof mass, which is allowed to move under acceleration conditions. In this paper, we design and fabrication a novel thermal-bubble-based micromachined accelerometer with advantages of minimum solid thermal conductance and high sensitivity successfully. The proposed accelerometer based on thermal convection creates a tiny heated air bubble hermetically sealed inside the sensor package cavity. Four thermopiles around the center heater serve as the temperature sensors to detect two-dimension motion of the chip and also are adequately applied to the technology of inclinometers, anemometers and flow meters. A new micro-link structure is also proposed to enhance the construction of accelerometer with the micro heater and two pairs of thermopiles floating over an etched cavity. The heater and the thermopiles are connected by network-like structure of micro-links, which enhance the structure and greatly reduce the solid heat flow from the heater to the hot junctions of thermopiles. The samples are fabricated by TSMC 0.35μm 2P4M CMOS process which is provided by CIC with outstanding strong structures and uniform quality. Our design is proved to be adequate for commercial batch production. We measure the output signal by inclining the sensor to evaluate the performance of this accelerometer.

Abstract: A high-sensitivity infrared detector requires small thermal capacitance and small thermal conductance to maximize the temperature change and signal induced by incident IR radiation. The suspended structure of infrared sensors provides ideal, thermally isolated, structures for support of the thin film detector. A new idea of improving CMOS thermopile performance is introduced to reduce the thermal conductance by dividing the thermocouple into several segments, which greatly increase the heat flow barrier. Then, adjacent segments are connected by a minimum width of alumina wire, which change the heat path and accumulated heat at the joint points. Several designs of infrared microsensors can improve performance of signal with reduce of thermal conductance. To that end, by using some adequate designs of polysilicon architecture, we can greatly reduce the heat flow from the main stream without introducing further electric resistance, which is related with noise. The design and simulation of thermopile sensors are realized by using the process parameters of standard 0.351m CMOS IC technology. Firstly we develop such a structure of thermopile with low thermal conductance and high performance by using CMOS compatible process which can be easily and naturally fabricated. The simulation results show good match with our original idea and great performance than before.