Low cost fabrication of passive microfluidic devices

This paper presents a low cost method for fabrication of microchannels on glass substrates for microfluidic devices applications. The channels with the depth up to 150um can be achieved by implementing a typical photoresist and wet etching process without any complicated deposition methods such as CVD, evaporation or other sophisticated techniques. In particular, AZ5214 photoresist is for the first time introduced for glass etching mask which can strongly resist against etchant attacks up to 2 hours, showing high accuracy for fabrication of microfluidic microchannels. The width of the channels is determined by the width of the lines in photo-mask design and the etch rate of the substrate because of glass isotropic etching characteristics. In practical the channel width range about 30μm to 350μm is attainable. Commercially available inexpensive microscopic slides have been used as substrate for etching channels using special etchant solutions. The etch rate of the glass strongly depends on the concentration of the etchant. Achieving smooth and clear surface after wet etching process is an important factor for easily flowing fluid through channels and monitoring purposes. A mixture of different solutions with special ratios has been applied to achieve smooth and clear surface of the etching regions. Two different bonding techniques, optical UV curable glue, and glass-PDMS-glass methods for adhering the etched glass substrate and non-etched glass cover is applied. A novel method for packaging, tubing and fittings for microfluidic devices using PMMA has been presented without the need for any drilling process.