Sensors and actuators a-physical vol:110 issue:1-3 pages:432-438
A readout circuit for a passive telemetric intra-ocular pressure (IOP) sensor is being developed. The intra-ocular sensor consists of capacitive pressure sensor in parallel with a planar coil. This inductor-capacitor (LC) resonant circuit transduces the pressure into a of resonance frequency. A voltage controlled oscillator (VCO) is used to excite the sensor over a large frequency range hereby detecting resonance of the internal sensor, and thus enabling the measurement of the intra-ocular pressure. This low power is extremely compact, making it suitable for long-term ambulant patient monitoring. The circuit allows wireless readout of the pressure transducers. Tests show promising results at mutual coil distances up to 7.5 mm. (C) 2003 Published by Elsevier B.V.