Responsible time shorting of flexible thermal flow sensor for medical applications

A flexible flow sensor, based on a copper-on-polyimide (COP) substrate, for medical applications was fabricated and experimentally shown to have a shorter response time (by about half) than that of a previously reported sensor. Heat generated around the heater formed on a polyimide thin membrane was successfully isolated, and the response time of the sensor was shortened to a half by enlarging the cavity in the under the heater and widening the gap between the heater and the contact hole for the electrical feed-through. To evaluate the characteristic of the fabricated sensor under reciprocating-flow conditions, it was applied to measurements of air flow in an artificial ventilator. The evaluation results show that the sensor output periodically changed with a time interval of 910 ms, which corresponds to the output frequency of the ventilator.