R. Kersjes et al., AN INVASIVE CATHETER FLOW SENSOR WITH ON-CHIP CMOS READOUT ELECTRONICS FOR THE ONLINE DETERMINATION OF BLOOD-FLOW, Sensors and actuators. A, Physical, 54(1-3), 1996, pp. 563-567
A silicon flow sensor with integrated electronics for invasive blood-f
low measurement has been developed and investigated. The flow sensor i
s based on a silicon-on-insulator SIMOX (separation by implanted oxyge
n) substrate with a backside etched silicon membrane containing oxide
trenches and uses a differential thermal measurement principle. The ch
osen fabrication process is fully CMOS-compatible. An on-chip switched
-capacitor circuitry converts the Row signal into a pulse-width-modula
ted signal. The device has been tested in a blood-circulation simulato
r in the flow range 0-101 min(-1) within a vessel with a diameter of 2
cm. It has been found to be useful for the observation of time-depend
ent flow pulses as well as for the determination of the cardiac output
. A prototype version of the Bow-sensor system has a membrane temperat
ure of less than 2 K above ambient temperature, a total power consumpt
ion of 5 mW and shows a pulse-width change from 45 to 25 mu s for the
flow range 0-101 min-(1).