The fabrication of hydrogel as a microvalve in microfluidic system
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0897-J03-19.1
The Fabrication of Hydrogel as a Microvalve in Microfluidic System Chehung Wei and Jui-Hung Chen Department of Mechanical Engineering Tatung University, Taipei 10462, Taiwan ABSTRACT The small volume of sample and fast response time are the primary features of micro fluidic system. It is essential for expensive samples. Microvalve is a key to regulate the flow movement component in an integrated microfluidic system. The working principle of conventional microvalves relies on its mechanical or electromagnetic properties. These valves are neither biocompatible nor are suitable for bioassays. Stimuli-response hydrogels whose properties of efficient mode of energy conversion (chemical to mechanical), excellent biocompatibility and the combination of multiple function (sensing and actuation) have become the leading candidate as engineered microscale components. In this paper, we study the feasibility of thermo-sensitive hydrogel as a valve on the microchip. A metal resistor was used as the temperature regulator. The results show that the miniaturization fabrication of the hydrogel depends on many factors like the volume of the hydrogel (the size of the valve), the vacuum condition (the evaporation rate) and the deposition substrate. The degree of swelling and deswelling of the hydrogel valve depends on the size of the hydrogel. This micro fluidic system is regulated by temperature change of the aqueous solution. The integration with other fluidic component is crucial for practical application.
INTRODUCTION In general bioassay experiment, the precise transportation of sample is very important for accurate results. In sampling and separation process, the valve is a critical component to precisely regulate the flow in microfluidic system. In conventional microfluidics, silicon is the common valve material due to the traditional semiconductor fabrication technology. However, the issues of biocompatibility and integration lead to the search for other valve materials. Polymer based material like hydrogel is an excellent alternative valve material due to its rheology properties, energy conversion efficiency and biocompatibility. Hydrogel is a hydro-swelling network consisting of hydrophilic homopolymers or copolymers. By changing different chemistry of the end group, different hydrogels have been developed to respond the stimulation of external environment such as pH [1], electric field [2], glucose [3], magnetic field [4] and temperature [5-6]. Among the thermo-responsive hydrogel, Poly(NIPAAm) is widely used as biomaterial. Its excellent biocompatibility suggests the use in the applications of microfluidic systems. While the bulk property of NIPAAm gels has been extensively studied, it is not clear whether it can be applied to small device like bioassay. The purpose of this research is to design a simple microfluidic system with hydrogel as the valve material and study the feasibility of the fabrication and its function.
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EXPERIMENTAL DETAILS Microfluidic device fabrication process A fluid chan
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