Feasibility Study and Preliminary Testing of 3-D Printing on ASICs for MEMS: A Particulate Sensor Case Study

Over the past two decades, additive manufacturing (AM) and 3-D printing have been widely used for producing macroscale industrial components. More recently, researchers have explored their application in fabricating microstructures and micro-electro-mechanical systems (MEMS). This field faces challenges related to accuracy, resolution, repeatability, scalability, and material compatibility. AM processes are classified into seven categories, with various subtypes and acronyms commonly used in industry. This study, conducted in collaboration between the Sant'Anna Institute of Biorobotics and STMicroelectronics, investigates the feasibility of integrating 3-D printing with application-specific integrated circuit fabrication to create fully functional MEMS. The research focuses on developing capacitive particulate sensors, which detect airborne particles through variations in capacitance between electrode pairs. The project involved the development of two different electrode configurations. Due to limitations in 3-D printing conductive materials at microscopic scales, electrodes were fabricated using a two-step process: 3-D printing with dielectric material followed by gold metallization. Electrical characterization was performed to evaluate resistance and capacitance values. Results indicated challenges in adhesion, uniform metallization, and measurement accuracy, particularly for smaller scale designs. While certain challenges remain, this study offers valuable insights into enhancing AM processes for MEMS production, and lays the groundwork for future developments in microscale 3-D printing technologies.