摘要： Chemical and biological sensors were initially explored at the microscale as an extension of microchip technology. They have considerable advantages because of their rapid throughput, and the need for very small samples. The development of better and smaller photometric and fluorometric detectors has enabled optical absorbance systems to be produced on a chip. Electrochemical sensors measure the conductance of electrolytes in an aqueous sample, and can also measure concentrations of gases that diffuse into the sample. This makes them valuable as personal health care monitors. These systems have been applied in medical monitoring, and for monitoring and controlling industrial-scale reactions. The integrated chemFET device is an example of a real-world application of this technology, and measures pH. The device is based on the ion-sensitive field-effect transistor (ISFET), which is caused by ions in solution producing a current across a transistor. Changes in the pH produce a proportionate change in the signal. Biological material, including DNA and cells, can also be used as a sensor. Cells have been used to detect pathogens in food, by adhering them to a sensor’s surface by means of a polymer, and then detecting changes in their electrochemistry. DNA optical readout is a widely accepted method for analyzing DNA sequences.