Low-Cost Fabrication of a PDMS Microchannel Using an Improved Print-and-Peel (PAP) Method

Abstract

Abstract-Microfluidics involves fluid dynamics, controlled fluid manipulations, and design of devices or systems in microchannels with typical dimensions of 10 to 200 micrometers. The conventional fabrication method of polydimethylsiloxane (PDMS) microchannels is soft lithography, which involves an expensive process for the preparation of master. The study aims to fabricate microchannels using print-and-peel (PAP) method for simple and low-cost construction of microfluidic systems. Based on the PAP method, a PDMS microchannel is developed using a master based on inkjet ink relief printed on paper. The study improves on the existing methodologies for PAP method by devising a technique called "printing-over", which is reprinting of the same pattern over itself at a high precision by modifying the printing process. This can produce irregularly-shaped molds with dimensions that can reach up to 200 micrometer width and 14.8 micrometer height, with aspect ratio equal to 0.07. Moreover, the aspect ratio is found to increase proportionally with number of printing-over runs. The microchannel produced from the mold has dimensions of 155 by 10 micrometers with aspect ratio of 0.06. With a rough cost analysis, the capital and variable costs of the PAP inkjet method are significantly lower than that of photolithography.Index Terms-Low-cost microfluidics, polydimethylsiloxane, print-and-peel method, inkjet printing. I. INTRODUCTIONMicrofluidics is the science that deals with the flow of liquids inside micrometer-size channels. This technology has found applications in various areas including biomedical engineering, cell biology, drug screening, chemical reaction engineering, and electrochemistry. While the main advantage of microfluidics is the reduction of costs by reducing fluid volumes, the conventional fabrication process requires specialized equipment in laboratories; and the material used, usually silicon chips, can be expensive to produce. Inducing controlled fluid flows in microfluidic channels is done using special equipment called microsyringe pumps, but these are also too expensive and are unavailable locally. The high costs associated with the fabrication of microfluidics consequently limits accessibility and thus, hinders its development especially in low-resource settings.The conventional fabrication method of polydimethylsiloxane (PDMS) microchannels is soft lithography, which involves an expensive process for the Manuscript received October 8, 2016; revised January 18, 2017. This work was supported in part by the UP Engineering Research and Development Foundation, Inc. (ERDFI) and the College of Engineering, University of the Philippines Diliman.The authors are with University of the Philippines Diliman, Quezon City 1101, Philippines (e-mail: kristian.yap@gmail.com). preparation of master called photolithography. Photolithography is a patterning process where light is used to transfer a pattern from a mask to a photosensitive polymer layer, and this resulting pattern can either be etched into the underlying su...