Fabrication of an array of silicon microscales for the monitoring of chemical processes

We present the fabrication and demonstration of a two-dimensional array of scales micromachined in silicon. Each scale consists of a platform suspended by a spring. The mass present on the platform of each scale is measured from a distance by a camera, which is imaging the fringe pattern that arises from optical interference in an air gap under each scale. A diffractive lens at the bottom of the gap separates the fringe signal from unwanted reflections and directs the fringe signal towards the camera. When a mass deflects a scale platform downwards, the gap narrows at the scale centre and the fringe pattern gets tighter. Operation at temperatures as high as 700 °C was demonstrated, which makes the presented device useful for the monitoring of high-temperature chemical processes.