Transparent glass force plate with CrN strain gauges featuring a notch structure

Abstract

Microforce plate is a powerful tool as force sensors in the field of microelectromechanical systems (MEMS). These force plates can be used to quantitatively measure the minute insects' ground reaction forces and microdroplets' collision forces. During such measurements, there is often a demand specification for observing the interface between the object and the plate from the backside. However, transparent materials were not compatible with traditional MEMS force plate fabrication processes. Here, we propose a fabrication process for a transparent glass force plate by forming a 3D notch structure on a glass substrate using chromium nitride (CrN) as a strain gauge. The force plate was designed as a 10 × 10 × 0.1 mm plate supported by beams on all four sides. The plate shape and groove formation were easily realized by applying a laser machining process to glass cutting. The force applied to the plate was measured using CrN strain gauges placed on a support beam. The fabricated force plate achieved a force resolution of less than 1 mN in the range of 100 mN. Additionally, the positional error across the entire plate was approximately ±10%. The proposed glass force plate is expected to be utilized in small-force measurements such as droplet collision observations, which require transparent plates for optical observation.