Wafer-level fabrication of polymer microsensors with integrated heat control

This paper described a novel wafer-level fabrication of polymer microsensors on the injection-molded thin polymer membrane with integrated heat control by conventional semiconductor processing techniques including standard photolithographic methods. A COC 5-in. wafer (1 mm thickness) is fabricated using injection molding method, in which polymer membranes (ca. 130 μm thick and 3 mm × 6 mm in area) are implemented simultaneously to reduce local thermal mass around micropatterned heaters and temperature sensors. The highly polished surface (ca. 4-nm) of the COC wafer makes it possible to use the standard photolithographic protocols. Gold micropatterns are fabricated for making microheaters, temperature sensors, and microelectrodes. An insulating layer of aluminum oxide (Al₂O₃) is prepared by using atomic layer deposition and micropatterning for the electrode contacts. The microdevice for heating and temperature sensing shows improved performance of thermal isolation, and microelectrodes display good electrochemical performances for electrochemical sensors.