Suresh Murugesan

A Plastic Micro Injection Molding Technique Using Replaceable Mold-Disks for Disposable Microfluidic Systems and Biochips

This paper presents an innovative plastic micro injection molding technique using replaceable disk-mold for applications to microfluidic systems and biochips. Precisely patterned and microfabricated wafer-type mold inserts can be easily loaded into the injection molding machine. Processing time for one chip was as fast as 10 seconds while hot embossing techniques require at least several minutes. Less than a few urn of precise patterns were also achieved. A promising new material has also been introduced and characterized using the developed injection molding technique as well as demonstrated for a disposable biochip.

A disposable plastic biochip cartridge with on-chip power sources for blood analysis

This paper presents the development of a disposable plastic biochip with embedded on-chip power sources and integrated biosensor array for applications in clinical diagnostics and point-of-care systems. A cartridge type disposable plastic biochip has been successfully developed and demonstrated for precise sample volume control with smart microfluidic manipulation without costly on-chip active microfluidic components. In addition, the disposable plastic biochip has successfully been tested for the measurements of partial oxygen concentration, glucose, and lactate level in human blood using an integrated biosensor array.

Effect of Surface Modification on Thermoplastic Fusion Bonding for 3-D Microfluidics

In this work we have characterized the effect of surface modification, using plasma treatment, on the bond strength of thermoplastic fusion bonding. We have investigated the effect of hydrophilic and hydrophobic surface treatments, for COC (cyclic olefin copolymers), on the bond strength and we show that the hydrophilic surface treatment increases the bond strength whereas; hydrophobic surface treatment significantly lowers the bond strength. The results of this work are of immediate relevance to plastic micromachining techniques for biochip applications and point-of-care systems.

Surface Modification of Cyclic Olefinic Copolymers for Bio-Mems Microfluidic Devices

Cyclic Olefin copolymers (COC) are a new class of polymers that may prove to be extremely useful in injection molding of micron scale fluidic devices. In microfluidic devices it is desirable to have a hydrophilic surface such as in flow driven by capillary action. However, such hydrophilic surfaces tend to display protein deposition when contacted with blood unlike hydrophobic surfaces. Alternatives to capillary action are then needed to control fluid flow for hydrophobic surfaces. Our goal in this research is to tune the slightly hydrophobic COC surfaces through simple surface modifications that are amenable to injection molding and other processing methods. In this study, the surface of an injection molded microfluidic component made from COC was modified in order to change the surface properties important to bio-fluidic devices. Some of the techniques used in this study were plasma treatments and ASG (aerosol gel) coating. Plasma treatments were conducted by using O 2 , CF 4 and their combination gas. O 2 treated surfaces became hydrophilic with increasing time of treatment. Combining O 2 and CF 4 made the surfaces more hydrophobic compared to CF 4 only. The structural changes after the plasma treatments were examined by ATR (Attenuated Total Reflectance) spectroscopy. Titania and silica particles from the ASG process were synthesized from titanium iso -propoxide and tetraethoxysilane, respectively. Titania coated surfaces became more hydrophilic and the silica coated surfaces did not have much change in their surface characteristics. The hydrophobicity of the plastic surfaces was measured by their contact angle with water. The implication of these treatments on bio-fluidic devices and their adaptation to the injection molding process will also be discussed.

Disposable Biochip Cartridge for Clinical Diagnostics Toward Point-of-Care Systems

This paper presents a prototype disposable biochip cartridge and biochip analyzer for clinical diagnostics toward point-of-care systems. The prototype disposable biochip, which has been fully micromachined using plastic micro-injection molding, is presented and demonstrated for analysis of human blood sample with the prototype biochip analyzer. With the developed prototype biochip cartridge and analyser, PO2 (partial oxygen pressure concentration) and glucose level in human blood sample have been successfully measured in less than a minute.