Integrated microfluidic biochips for immunoassay and DNA bioassays

Abstract

Bioassays involve multi-stage sample processing and fluidic handling, which are generally labor-intensive and time-consuming. Using microfluidic technology to integrate and automate all these steps in a single chip device is highly desirable in many practical applications such as clinical diagnostic and in-field environmental testing. We have developed self-contained and fully integrated biochip systems for immunoassay and DNA analysis. These microfluidic biochip devices can perform detection of multiple bioagents (including antigens and DNA) using electrochemical detection methods. Microfluidic mixer, valves, pumps, channels, chambers, and Combimatrix microelectrode array are integrated to perform parallel immunoassays to detect infectious particles (viruses and bacteria) from complex biological samples in a single, fully automated biochip device. All microfluidic components use very simple and inexpensive approaches in order to reduce chip complexity. Back-end detection is accomplished using an enzyme-based electrochemical detection method that has many advantages including high sensitivity ( approximately fM) and simple apparatus. The sensor is a miniaturized array of individually addressable microelectrodes controlled by active CMOS circuitry. Pathogenic bacteria and DNA detections are both demonstrated. The devices with capabilities of on-chip sample processing and detection provide a cost-effective solution to direct sample-to-answer biological analysis for point-of-care genetic analysis, disease diagnosis, and in-field bio-threat detection.