Design and Fabrication of a Spin Coater with In-Situ Optical Measurement for Soft Thin Films
This study addresses the challenge of achieving non-destructive, high-precision, and low-cost thickness control of soft polymeric films during spin coating—a critical limitation for devices such as dielectric elastomer actuators. The authors present a low-cost, desktop-scale spin-coating platform based on 3D printing, integrated for the first time with a low-deformation, laser-reflection-based in situ thickness measurement system. By employing a quadrant photodetector to track real-time displacement of the reflected laser beam, the system enables controlled fabrication of soft films with thicknesses ranging from 50 to 300 µm. Optimized via finite element analysis and calibrated using metal shims, the setup achieves a thickness resolution of 3.6–3.7 µm and a repeatability error of 13 µm (95% confidence interval), successfully producing silicone films with deviations from target thickness of less than 9 µm.