Design and Fabrication of a Spin Coater with In-Situ Optical Measurement for Soft Thin Films
For researchers fabricating soft elastomer films (e.g., for dielectric elastomer actuators), this provides an accessible, low-cost alternative to expensive industrial spin coaters with in-situ thickness monitoring.
This work presents a low-cost, 3D-printed spin coater with integrated optical thickness measurement for soft thin films (50-300 µm). The system achieves thickness resolution of 3.6-3.7 µm and repeatability within 13 µm, producing silicone films within 9 µm of target thickness.
Spin coating is widely used for fabrication of thin polymer and elastomer films, yet reliable thickness verification of highly compliant materials remains challenging due to deformation from contact-based measurements and the cost and complexity of conventional optical metrology. Accurate thickness control is especially critical in soft elastomer applications such as dielectric elastomer actuators (DEAs), where mechanical and functional performance scales strongly with film thickness. This work presents a low-cost, primarily 3D-printed benchtop spin coater with an integrated, minimally deforming optical thickness measurement system for soft-film fabrication workflows. The system is designed to manufacture films between 50 and 300 microns thick with repeatability within 10 microns. Thickness is measured in-situ by tracking displacement of a reflected laser beam via quadrant photodetector, avoiding significant deformation. Optical geometry, sensor linearity constraints, and structural validation via finite element analysis are discussed. Experimental validation using calibrated metal shims demonstrated a thickness resolution of 3.6-3.7 microns and best-case measurement repeatability of 13 microns (95 percent confidence interval). The platform repeatably produced silicone films within 9 microns of target thickness, demonstrating that accessible optical metrology can be integrated into a low-cost spin coating system for practical, thickness-controlled fabrication of compliant thin films without specialized industrial instrumentation.