A simple and reliable microfabrication process for a programmable microvalve array.

We describe our reliable methodology for fabricating a complex programmable microvalve array (PMA) and its integration with a glass microcapillary electrophoresis chip. This methodology is applicable to any device that requires multilayered PDMS, multiple alignment processes, selective PDMS bonding, and multilayered integration with downstream sensing systems. Along with the detailed step-by-step process, we discuss essential quality assurance checks that can be performed throughout fabrication to assist in troubleshooting and maximizing chip yield.

Digital microfluidics using a differentially polarized interface (DPI) to enhance translational force.

Direct current (DC)-digital microfluidics (DMF) enables the manipulation of droplets to revolutionize medical diagnostics, environmental assays, and fundamental biology. However, DC-DMF requires high voltages to generate droplet motion, which often breaks dielectric layers at the micro/nano scale, causing electrolysis. To minimize these issues, oil-fillers are commonly used to decrease the voltage requirement by reducing the surface tension of the droplet to the surrounding fluid.

Feasibility of Detecting Bioorganic Compounds in Enceladus Plumes with the Enceladus Organic Analyzer.

Enceladus presents an excellent opportunity to detect organic molecules that are relevant for habitability as well as bioorganic molecules that provide evidence for extraterrestrial life because Enceladus' plume is composed of material from the subsurface ocean that has a high habitability potential and significant organic content. A primary challenge is to send instruments to Enceladus that can efficiently sample organic molecules in the plume and analyze for the most relevant molecules with the necessary detection limits. To this end, we present the scientific feasibility and engineering design of the Enceladus Organic Analyzer (EOA) that uses a microfluidic capillary electrophoresis system to provide sensitive detection of a wide range of relevant organic molecules, including amines, amino acids, and carboxylic acids, with ppm plume-detection limits (100 pM limits of detection).

A fully automated microfluidic micellar electrokinetic chromatography analyzer for organic compound detection.

An integrated microfluidic chemical analyzer utilizing micellar electrokinetic chromatography (MEKC) is developed using a pneumatically actuated Lifting-Gate microvalve array and a capillary zone electrophoresis (CZE) chip. Each of the necessary liquid handling processes such as metering, mixing, transferring, and washing steps are performed autonomously by the microvalve array. In addition, a method is presented for automated washing of the high resistance CZE channel for device reuse and periodic automated in situ analyses.

Fabrication of PDMS Nanocomposite Materials and Nanostructures for Biomedical Nanosystems.

Recent applications of PDMS nanocomposite materials and nanostructures have dramatically increased in biomedical fields due to optical, mechanical and electrical properties that are controllable by nanoengineering fabrication processes. These applications include biomedical imaging, biosensing, and cellular bioengineering studies using PDMS engineered structures with nanoparticles, nanopillars and functional nanoporous membranes. This article reviews the recent progress of PDMS nanocomposite materials and nanostructures and provides descriptions of various fabrication techniques.

Biomimetic cardiac microsystems for pathophysiological studies and drug screens.

Microfabricated organs-on-chips consist of tissue-engineered 3D in vitro models, which rely on engineering design and provide the physiological context of human organs. Recently, significant effort has been devoted to the creation of a biomimetic cardiac system by using microfabrication techniques. By applying allometric scaling laws, microengineered cardiac systems simulating arterial flow, pulse properties, and architectural environments have been implemented, allowing high-throughput pathophysiological experiments and drug screens.