Fabrication of Wireless Micro Pressure Sensor Using the CMOS Process

In this study, we fabricated a wireless micro FET (field effect transistor) pressure sensor based on the commercial CMOS (complementary metal oxide semiconductor) process and a post-process. The wireless micro pressure sensor is composed of a FET pressure sensor, an oscillator, an amplifier and an antenna. The oscillator is adopted to generate an ac signal, and the amplifier is used to amplify the sensing signal of the pressure sensor. The antenna is utilized to transmit the output voltage of the pressure sensor to a receiver. The pressure sensor is constructed by 16 sensing cells in parallel. Each sensing cell contains an MOS (metal oxide semiconductor) and a suspended membrane, which the gate of the MOS is the suspended membrane. The post-process employs etchants to etch the sacrificial layers in the pressure sensor for releasing the suspended membranes, and a LPCVD (low pressure chemical vapor deposition) parylene is adopted to seal the etch holes in the pressure. Experimental results show that the pressure sensor has a sensitivity of 0.08 mV/kPa in the pressure range of 0–500 kPa and a wireless transmission distance of 10 cm

Capacitive Micro Pressure Sensor Integrated with a Ring Oscillator Circuit on Chip

The study investigates a capacitive micro pressure sensor integrated with a ring oscillator circuit on a chip. The integrated capacitive pressure sensor is fabricated using the commercial CMOS (complementary metal oxide semiconductor) process and a post-process. The ring oscillator is employed to convert the capacitance of the pressure sensor into the frequency output. The pressure sensor consists of 16 sensing cells in parallel. Each sensing cell contains a top electrode and a lower electrode, and the top electrode is a sandwich membrane. The pressure sensor needs a post-CMOS process to release the membranes after completion of the CMOS process. The post-process uses etchants to etch the sacrificial layers, and to release the membranes. The advantages of the post-process include easy execution and low cost. Experimental results reveal that the pressure sensor has a high sensitivity of 7 Hz/Pa in the pressure range of 0–300 kPa

Flexible Temperature Sensor Array Based on a Graphite-Polydimethylsiloxane Composite

This paper presents a novel method to fabricate temperature sensor arrays by dispensing a graphite-polydimethylsiloxane composite on flexible polyimide films. The fabricated temperature sensor array has 64 sensing cells in a 4 × 4 cm2 area. The sensor array can be used as humanoid artificial skin for sensation system of robots. Interdigitated copper electrodes were patterned on the flexible polyimide substrate for determining the resistivity change of the composites subjected to ambient temperature variations. Polydimethylsiloxane was used as the matrix. Composites of different graphite volume fractions for large dynamic range from 30 °C to 110 °C have been investigated. Our experiments showed that graphite powder provided the composite high temperature sensitivity. The fabricated temperature sensor array has been tested. The detected temperature contours are in good agreement with the shapes and magnitudes of different heat sources