Abstract
We have successfully demonstrated an on-chip digital pressure control scheme that can be readily automated and programmed, and a 3D fabrication and integration scheme that can realize hybrid structures with sophisticated functions. A composite 3D structure with an elastomer diaphragm sandwiched between input and reference pressures is utilized to filter out fluctuation and guide the pressure output. The reference pressure, which is set by a D/A converter, and therefore the pressure output can switch rapidly and precisely between levels on demand. To fabricate the desired 3D hybrid structures, a DLP-Stereolithography process is developed, which prints PMMA parts and molds for PDMS duplication. For many existing microfluidic systems, their functions are achieved passively by adjusting the flows driven by multiple syringe pumps, which are costly and difficult to scale up. To address the need for scalability and improved controllability, active schemes using pneumatic actuation have been demonstrated. The presented on-chip pressure controllers, which can replace their bulky and costly counterparts, are crucial for microfluidic systems. Compared to the previously published results, our scheme shows improvements in accuracy and functionality. It takes less than 0.1 seconds to switch between certain pressure levels. Furthermore, the demonstrated fabrication and integration process provides a powerful and economic alternative for polymer microfabrication. As such, sophisticated and automated control of pneumatically driven microfluidic chips and soft robots can potentially be realized.