Chip-scale integration of data-gathering microsystems

Integrated microsystems merging embedded computing with sensing and actuation are poised to dramatically expand our ability to gather information from the nonelectronic world. Examples include a microassembled multichip electronic interface to the brain, an integrated electrofluidic gas chromatography system for environmental monitoring, and a wireless intra-arterial microsystem for pressure and flow measurements. In general, such microsystems will consist of a few chips, integrated in generic platforms that are customized for a given-application by the sensors selected and by software. This paper illustrates this approach with a 0.15-cm(3) multisensor microsystem for autonomously sensing and storing environmental and biological data. The microsystem is formed using on-board pressure/temperature/humidity sensors, off-board strain gauges and neural/EMG electrodes, a custom sensor-interface chip, a mixed-signal microcontroller, and a nonvolatile memory. These components allow the acquisition and storage of multidomain data at low power levels (<50 mu W reading capacitive sensors at 1 Hz). The system is programmable in gain (0.4-3.2 mV/fF), offset (lob), accuracy (14b), and sampling rate (0.1 Hz-10 kHz) and is integrated in a micromachined silicon platform that implements through-wafer interconnects, solder-based microconnectors, and recessed cavities for chip-stacking. The microsystem is realized in 9.5 mm x 7.6 mm x 2.0 mm (0.15 cm(3))(<0.5 cm(3) with a lithium battery).