Mobile patient monitoring based on impedance-loaded SAW-sensors.
A remotely requestable, passive, short-range sensor network for measuring small voltages is presented. The sensor system is able to simultaneously monitor six small voltages in millivolt-range, and it can be used for Holter-electrocardiogram (ECG) and other biopotential monitoring, or in industrial applications. The sensors are based on a surface acoustic wave (SAW) delay line with voltage-dependent, impedance loading on a reflector interdigital transducer (IDT). The load circuit impedance is varied by the capacitance of the voltage-controlled varactor. High resolution is achieved by developing a MOS-capacitor with a thin oxide, low flat-band voltage, and zero-voltage capacitance in the space-charge region, as well as a high-Q-microcoil by thick metal electroplating. Simultaneous monitoring of multiple potentials is realized by time-division-multiplexing of different sensor signals.
Karilainen
Anna
A
Department of Microsystems Technology, Technical University Hamburg-Harburg, Hamburg, Germany. anna.karilainen@tuhh.de
Finnberg
Thomas
T
Uelzen
Thorsten
T
Dembowski
Klaus
K
Müller
Jörg
J
D000162:Acoustics / Q000295:instrumentation*; D017097:Electric Impedance; D015716:Electrocardiography, Ambulatory / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D018670:Monitoring, Ambulatory / Q000295:instrumentation / Q000379:methods; D013686:Telemetry / Q000295:instrumentation* / Q000379:methods; D014159:Transducers