A 40 /spl mu/A/channel compensated 18-channel strain gauge measurement system for stress monitoring in dental implants

This paper presents an ASIC of an autonomous monitoring system that is capable of measuring 18 strain gauges simultaneously. The sensor interface chip is implemented in a 0.7 /spl mu/m CMOS technology and includes a PTAT-current reference, an 8-bit DAC, together with a digital interface for multi-gauge nulling, an SC instrumentation amplifier, an SC S/H and a 9-bit successive approximation ADC. The accuracy is better than 20 /spl mu/strain, while consuming only 40 /spl mu/A/channel.