Abstract
Microvalves play an important role in fluid control in micro total analysis systems (µTAS). Previous studies have reported complex fabrication processes for making microvalve elements in a channel. Hence, there is a need for a simpler microvalve fabrication method for achieving throughput improvement and cost reduction in µTAS. In this study, we propose a simple fabrication method for a magnetically driven microvalve array using a photosensitive composite. The composite was prepared by mixing a photoresist and magnetic particles of pure iron. The simple fabrication process was performed by using a laminating layer composed of a sacrificial part and the composite in a channel. The microvalve elements were fabricated by one-step photolithography using the processability of the sacrificial layer and composite. Further, we demonstrated the magnetic driving property of the fabricated microvalve array device. Compared to devices containing non-driving microvalves, the flow rate was decreased by 50%, and the pressure difference between the inlet and outlet increased by up to 4 kPa with increase in driving microvalve elements. These results imply that our proposed device could be useful for practical µTAS applications.
Highlights
Micro total analysis systems have attracted attention owing to their feasibility as a tip-sized chemical testing and sample analysis device
Because μTAS are integrated with multiple microfluidic devices fabricated with micro electro mechanical system (MEMS) technology, they afford reductions in sample consumption, detection time, and device size
Microvalves play an important role in fluid control and sample sorting in the μTAS
Summary
Micro total analysis systems (μTAS) have attracted attention owing to their feasibility as a tip-sized chemical testing and sample analysis device. In the case of chemically driven microvalves, control methods using UV-sensitive materials or air bubbles have been developed [13,14] Reports indicate that these microvalves show good fluid damming properties; they require multiple fabrication processes, such as photolithography, sputtering, and alignment, for assembly. To achieve reproducibility of the fabrication process, we optimized the process conditions by evaluating the composite mixing method, thickness and development properties of the sacrificial layer, and the composite processability Using this optimized fabrication process, we fabricated a microvalve array device with 100 serial-connected valve elements. The flow rate of the fluid flowing through the microvalves was controlled by a noncontact external magnetic field using a single magnet We expect that this fabricated device and technique could be useful for application in μTAS
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