Thermocouples fabricated on trench sidewall in microfluidic channel bonded with film cover

Abstract

Thermocouples on a trench sidewall fronting a flow are fabricated by three-dimensional (3D) photolithography. The conventional thermocouples on the wafer top surface are also fabricated. The performances of these devices are compared. Without the flow inside the microchannel, the thermocouple on the trench sidewall shows the same output voltage as that on the wafer top surface positioned 40μm from the channel. As a static response, when the microchannel is heated and room-temperature air flows inside the channel, the thermocouple on the sidewall shows a lower voltage. As a dynamic response, when hot air flows inside the channel and replaces the room-temperature air, the thermocouple on the sidewall shows a faster response, increasing its output voltage, and the local temperature of the flow can be measured more precisely.