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This work presents a thermal analysis on predicting the temperature increase and the voltage response of high-Tc superconducting bolometers. Two heat transfer models, that is, the surface heating model and the heat generation model considering the skin depth, are introduced and compared. The surface heating model is found to be valid only for situations where the skin depth is much smaller than the film thickness. To consider the thermal boundary resistance between film and substrate, a radiation-boundary-condition model based on acoustic mismatch model (AMM) and an interfacial-layer model (ILM) are employed. The thermal boundary resistance significantly influences the voltage response. Additionally, several common substrates are examined. SrTiO3 (100) or LaAlO3 (100) is a better substrate for high-Tc superconducting bolometers. One interesting finding was that when compared with experimental data, all the theoretical values from the present study as well as the other previously theoretical treatment overestimate the voltage response near the transition temperature.

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This paper describes the design and characterization of a capacitive tactile sensor fabricated in a conventional CMOS process. To achieve a high capacitive sensitivity, an oscillator circuit is adopted to convert the pressure induced capacitive change to an output frequency shift. The complete post micromachining steps are performed on a CMOS die without resorting to a wafer process. The pressure-sensing membrane has a total size of 200 µm × 200 µm with an initial sensing capacitance of 153 fF. Experimental results show an initial frequency output at 48.96 MHz under no applied load. The total frequency shift is 13.5 MHz with a corresponding membrane displacement of 0.56 µm and a capacitance change of 63 fF, averaging 0.21 MHz/fF. The measured force sensitivity is 26.1 kHz/µN.