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In molecular biology, biochips are essentially miniaturized laboratories that can perform hundreds or thousands of simultaneous biochemical reactions. Biochips enable researchers to quickly screen large numbers of biological analytes for a variety of purposes, from disease diagnosis to detection of bioterrorism agents. Digital microfluidic biochips have become one of the most promising technologies in many biomedical fields. In a digital microfluidic biochip, a group of (adjacent) cells in the microfluidic array can be configured to work as storage, functional operations, as well as for transporting fluid droplets dynamically. ==History== The development started with early work on the underlying sensor technology. One of the first portable, chemistry-based sensors was the glass pH electrode, invented in 1922 by Hughes (Hughes, 1922). In subsequent years. For example, a K+ sensor was produced by incorporating valinomycin into a thin membrane (Schultz, 1996). In 1953, Watson and Crick announced their discovery of the now familiar double helix structure of DNA molecules and set the stage for genetics research that continues to the present day (Nelson, 2000). The development of sequencing techniques in 1977 by Gilbert (Maxam, 1977) and Sanger (Sanger, 1977) (working separately) enabled researchers to directly read the genetic codes that provide instructions for protein synthesis. This research showed how hybridization of complementary single oligonucleotide strands could be used as a basis for DNA sensing. Two additional developments enabled the technology used in modern DNA-based . First, in 1983 Kary Mullis invented the polymerase chain reaction (PCR) technique (Nelson, 2000), a method for amplifying DNA concentrations. This discovery made possible the detection of extremely small quantities of DNA in samples. Secondly in 1986 Hood and co-workers devised a method to label DNA molecules with fluorescent tags instead of radiolabels (Smith, 1986), thus enabling hybridization experiments to be observed optically. Figure 1 shows the make up of a typical biochip platform. The actual sensing component (or "chip") is just one piece of a complete analysis system. Transduction must be done to translate the actual sensing event (DNA binding, oxidation/reduction, ''etc.'') into a format understandable by a computer (voltage, light intensity, mass, ''etc.''), which then enables additional analysis and processing to produce a final, human-readable output. The multiple technologies needed to make a successful biochip — from sensing chemistry, to microarraying, to signal processing — require a true multidisciplinary approach, making the barrier to entry steep. One of the first commercial biochips was introduced by Affymetrix. Their "GeneChip" products contain thousands of individual DNA sensors for use in sensing defects, or single nucleotide polymorphisms (SNPs), in genes such as p53 (a tumor suppressor) and BRCA1 and BRCA2 (related to breast cancer) (Cheng, 2001). The chips are produced using microlithography techniques traditionally used to fabricate integrated circuits (see below). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「biochip」の詳細全文を読む スポンサード リンク
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