Joseph H. Nevin

Disposable smart lab on a chip for point-of-care clinical diagnostics

This paper presents the development of a disposable plastic biochip incorporating smart passive microfluidics with embedded on-chip power sources and integrated biosensor array for applications in clinical diagnostics and point-of-care testing. The fully integrated disposable biochip is capable of precise volume control with smart microfluidic manipulation without costly on-chip microfluidic components. The biochip has a unique power source using on-chip pressurized air reservoirs, for microfluidic manipulation, avoiding the need for complex microfluidic pumps. 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. This paper presents details of the smart passive microfluidic system, the on-chip power source, and the biosensor array together with a detailed discussion of the plastic micromachining techniques used for chip fabrication. A handheld analyzer capable of multiparameter detection of clinically relevant parameters has also been developed to detect the signals from the cartridge type disposable biochip. The handheld analyzer developed in this work is currently the smallest analyzer capable of multiparameter detection for point-of-care testing.

An integrated microfluidic biochemical detection system for protein analysis with magnetic bead-based sampling capabilities

This paper presents the development and characterization of an integrated microfluidic biochemical detection system for fast and low-volume immunoassays using magnetic beads, which are used as both immobilization surfaces and bio-molecule carriers. Microfluidic components have been developed and integrated to construct a microfluidic biochemical detection system. Magnetic bead-based immunoassay, as a typical example of biochemical detection and analysis, has been successfully performed on the integrated microfluidic biochemical analysis system that includes a surface-mounted biofilter and electrochemical sensor on a glass microfluidic motherboard. Total time required for an immunoassay was less than 20 min including sample incubation time, and sample volume wasted was less than 50 microl during five repeated assays. Fast and low-volume biochemical analysis has been successfully achieved with the developed biofilter and immunosensor, which is integrated to the microfluidic system. Such a magnetic bead-based biochemical detection system, described in this paper, can be applied to protein analysis systems.

Development and Characterization of Microfluidic Devices and Systems for Magnetic Bead-Based Biochemical Detection

This paper presents the development and characterization of a generic microfluidic system for magnetic bead-based biochemical detection. Microfluidic and electrochemical detection devices such as microvalves, flow sensors, biofilters, and immunosensors have been successfully developed and individually characterized in this work. Magnetically driven microvalves, pulsed-mode microflow sensors, magnetic particle separators as biofilters, and electrochemical immunosensors have been sep-arately fabricated and tested. The fabricated microfluidic components have been surface-mounted on the microfluidic motherboard for fully integrated microfluidic biochemical detection system. A magnetic bio-bead approach has been adopted for both sampling and manipulating target biological molecules. Magnetic beads were used as both substrate of antibodies and carriers of target antigens for magnetic bead-based immunoassay, which was chosen as a proof-of-concept for the generic microfluidic bio-chemical detection system. The microfluidic and electrochemical immunosensing experiment results obtained from this work have shown that the biochemical sensing capability of the complete microfluidic subsystem is suitable for portable biochemical detection of bio-molecules. The methodology and system, which has been developed in this work, can be extended to generic bio-molecule detection and analysis systems by replacing antibody/antigen with appropriate bio receptors/reagents such as DNA fragments or oligonucleotides for application towards DNA analysis and/or high throughput protein analysis.

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 fully integrated biosensor array for measurement of metabolic parameters in human blood

This paper presents a fully integrated biosensor array, which includes an oxygen sensor and a glucose sensor, for measurement of metabolic parameters in human blood. Partial oxygen concentration and glucose concentration in human blood were successfully detected in less than one minute using the developed biosensor array. Total sensor design is based on low melting point gel-based solid electrolyte that simplified fabrication process. Most parameters that are relative to sensor performance were calibrated and compared to optimize the sensor design. Such parameters include membrane material, thickness of membrane and solid electrolyte layer, area of electrodes, distance between electrodes, and the shape of electrodes. We also integrated the developed biosensor array with microfluidic systems for precise control of sample delivery.

DC conduction mechanisms in thin polyimide films

Abstract The current-voltage characteristics of polyimide films from 4000 A to 11,000 A thick have been studied over a temperature range from 26 °C to 100°C. Below 60°C the conduction mechanism appears to be a combination of the Schottky and the Poole-Frenkel mechanisms. Between 60°C and 100°C, the conduction appears to be ionic and can be described by the rate theory. Ionic jump distances of between 252A and 274A have been estimated.

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.

An integrated microfluidic biochemical detection system with magnetic bead-based sampling and analysis capabilities

This paper presents the development and characterization of an integrated microfluidic biochemical detection system for fast and low volume immunoassays using magnetic beads, which are used as both immobilization surfaces and bio-molecule carriers. Magnetic bead-based immunoassay, as a typical example of biochemical detection and analysis, has been successfully performed on the integrated microfluidic biochemical analysis system that includes a surface-mounted biofilter and immunosensor on a glass microfluidic motherboard. Total time required for full immunoassay was less than 20 minutes including sample incubation time and sample volume wasted was less than 50 /spl mu/l during five repeated assays. Fast and low volume biochemical analysis has been successfully achieved with the developed biofilter and immunosensor, which is integrated to microfluidic system.

Thallium‐doped silicon ionization and excitation levels by infrared absorption

The thallium ionization level in silicon is the lone group‐III acceptor (of the classical outer s2p atomic configuration) remaining heretofore imprecisely defined. Thallium is also the only such impurity not previously defined as to its bound‐hole (inverse hydrogenic) excitation levels within the energy gap. From room‐temperature infrared absorption data the thallium level is here located at 0.255 eV above the top of the valence band in silicon. This compares with previously reported ionization values of 0.22, 0.26, and 0.30±0.03 eV, all determined by nonoptical methods. Six thallium hydrogenic bound‐hole excitation levels were identified within the energy gap.

Adhesion of aluminum films on polyimide by the electromagnetic tensile test

The electromagnetic tensile test has been adapted to the measurement of the adhesion of thin aluminum alloy films on polyimide. The adhesion per unit area was found to be weakly dependent on linewidth for lines as small as 5 µm. Processing conditions affected the adhesion with plasma ash and annealing steps improving the adhesion. Al 4% Cu was somewhat more adherent than Al-0.5% Cu.