HJ Science and Technology (United States)

Glass is one of the most convenient materials for the development of microfluidic devices. However, most fabrication protocols require long processing times and expensive facilities. As a convenient alternative, polymeric materials have been extensively used due their lower cost and versatility. Although CO2 laser ablation has been used for fast prototyping on polymeric materials, it cannot be applied to glass devices because the local heating causes thermal stress and results in extensive cracking. A few papers have shown the ablation of channels or thin holes (used as reservoirs) on glass but the process is still far away from yielding functional glass microfluidic devices. To address these shortcomings, this communication describes a simple method to engrave glass-based capillary electrophoresis devices using standard (1mm-thick) microscope glass slides. The process uses a sacrificial layer of wax as heat sink and enables the development of both channels (with semicircular shape) and pass-through reservoirs. Although microscope images showed some small cracks around the channels (that became irrelevant after sealing the engraved glass layer to PDMS) the proposed strategy is a leap forward in the application of the technology to glass. In order to demonstrate the capabilities of the approach, the separation of dopamine, catechol and uric acid was accomplished in less than 100s.

Programmable microfluidic platforms (PMPs) are enabling significant advances in the utility of microfluidics for chemical and biochemical analysis. Traditional microfluidic devices are analogous to application-specific devices--a new device is needed to implement each new chemical or biochemical assay. PMPs are analogous to digital electronic processors--all that is needed to implement a new assay is a change in the order of operations conducted by the device. In this review, we introduce PMPs based on normally-closed microvalves. We discuss recent applications of PMPs in diverse fields including genetic analysis, antibody-based biomarker analysis, and chemical analysis in planetary exploration. Prospects, challenges, and future concepts for this emerging technology will also be presented.