A2 . 3 W Wireless Intraocular Pressure/Temperature Monitor Yi-Chun Shih, Student Member , IEEE, Tueng Shen, and Brian P . Otis , Senior Member , IEEE

Abstract

We present the design of an ultra-low power, wire- less pressure/temperature sensin g device for continuous intraoc- ular pressure monitoring. The device is wirelessly pow ered and demonstrates a power consumption of 2.3 Wa t1 . 5Vd u r i n g continuous monitoring. The chip converts both capacitance and temperature to frequency using a time-interleaved relaxation oscil- lator, which modulates RF backscatter to a reader for computation of measured samples. A signi ficant reduction in power consump- tion results from the elimination of the dig itization circuitry, time- multiplexed operation, and moving the signal processing burden to the external reader using analog IF-modulated backscatter. The chip exhibits measured capacitance and t emperature standard de- viations of 1.4 fF and 0.4 C, respectively.