Electrochemical Biosensors and Microfluidics in Organic System-on-Package Technology

A nanobioelectronic system-on-package (SOP) with integrated electrochemical sensors, microfluidic channels and microneedles was demonstrated with organic compatible processes. A novel amperometric glucose sensor based on carbon nanotubes/glassy carbon working electrodes and glucose oxidase enzyme encapsulated in a sol-gel derived zirconia/nafion matrix was developed to demonstrate the biosensing. The sol-gel chemistry provides an attractive way to immobilize the sensitive biomolecules on the electrode at low temperatures. The amperometric measurements were carried out with a three-electrode system. SU8 epoxy based thick microfluidic channels were built over the electrode layer and then the enzyme was immobilized, followed by sealing of the channel with a PDMS membrane using a low temperature bonding process (60degC). The enzyme-catalyst reaction was recorded as the release of electrons from the oxidation of glucose into gluconolactone, hydrogen peroxide and subsequently into water. The results indicate that the response time is within few seconds. The current varied from 1 muA to 2.5 muA as the glucose concentration was increased from 5 mM to 20 mM. Finally, a compatible microneedle technology is demonstrated to enable transdermal fluid injection into the device for real-time health monitoring. Nanobio SOP with recent advances in nanobiosensing, nanomedicine, low-cost polymer-based high-density packaging, mixed-signal electronics can lead to the portable, reliable and cost effective biomedical devices of the future.