The current in vitro diagnostics (IVD) market in the US is estimated to be 19 billion dollars. 25% of that market is in immunoassays. Additionally, the immunoassay market is thought to be a much higher margin market than clinical chemistry and much more profitable. In today's market, some automated immunoassays are able to detect concentrations in the low attomole range, give results in 20 to 30 minutes and are low cost to produce. However, such current assays require several hundred microliters of specimen in order to achieve such a low detection limit. In fact, the first generation of rapid immunoassay devices utilize a wide variety of techniques for detection but nearly all were yes/no tests with no quantitation.Key challenges in miniaturization of immunoassays include the handling of ultra-small volumes of liquids (microfluidics) and detection of low numbers of antigen molecules. If a microdevice for an assay uses only 10 nanoliters of sample, a combination of methods including rapid concentration, high antibody density, and high sensitivity are needed. Therefore extremely sensitive and inexpensive microassay systems must be developed. The drive towards Point of Care (POC) technology has already produced several rapid immunoassay devices that yield results at a doctor's office or clinic within minutes.Researchers at Arizona State University have developed a simplified microfluidic chip on which small volumes of fluids are made to flow over specialized particles within the microchannels using electroosmosis or by a pressure gradient. Direct detection is affected using fluorescent conjugates. Such a microchip has been designed and constructed. A few of the immunoassay features made possible by this invention are as follows:1. Ultrafast analysis times as a result of direct detection2. Reuse of the microchip3. Flexibility for any immunoassay and multiple antigen analyses using a single chip.4. Good sensitivity5. Ultrasmall volumes small animal medical research, forensics, and non-invasive method.
|Published - Mar 10 2000