Fish and chips: single chip silicon MEMS CTDL salinity, temperature, pressure and light sensor for use in fisheries research

A single-chip silicon MEMS CTDL multi sensor for use in aqueous environments is presented. The new sensor chip consists of a conductivity sensor based on platinum electrodes (C), an ion-implanted thermistor temperature sensor (T), a piezoresistive pressure sensor (D for depth/pressure) and an ion-implanted p-n junction light sensor (L). The design and fabrication process is described. A temperature sensitivity of 0.8 /spl times/ 10/sup -3/K/sup -1/ has been measured and detailed analysis of conductivity measurement data shows a cell constant of 81 cm/sup -1/.