Design and fabrication of fast micro heaters for temperature programming micro gas chromatographs

Prototype, low power, high rate resistance heaters for temperature programming metal micro gas Chromatograph (GC) separation column chips were fabricated using UV lithography. Spin coated polyimide was used as the electrically insulating layer between the heating coil and the GC column chip because of its excellent thermal properties - in particular the ability to match the coefficient of thermal expansion with nickel and copper, and ease of application. Low resistivity, copper and nickel, metal heating elements were electrodeposited directly on the polyimide layer spin coated on top of the nickel GC column chips. In experiments, the microfabricated heaters were able to heat the GC column at rates from 5°C/sec to 50°C/sec under PID control, Temperatures from 125°C to 250°C were maintained for soak times of up to 30 seconds. The heaters can be used to generate a variety of temperature programming profiles and offer flexibility in selecting the different ramp rates and soak temperatures needed for different applications.