Search

When quantitative analysis or quantitative chemical synthesis is performed using a micrototal analysis system (microTAS), the technologies for precise metering, transporting, and mixing of droplets are required. In this chapter, several technologies for the handling of droplets are described. For metering, dispensing and transporting of droplets, pneumatic and electrokinetic forces are used. Separation of cells and particles is also performed by electrical operation. Other handling technique, such as ultrasonic or centrifugal force applications, are also reviewed. Robotic synthesis devices or high throughput screening devices are promising applications for these technologies. [ABSTRACT FROM AUTHOR]

The label-free, selective and sensitive detection of cells and viruses was successfully performed down to the nanogram and picogram range with acoustic transducers such as the quartz crystal microbalance and the surface acoustic wave resonators. Selectivity of these acoustic devices was optimized by combining them with sensitive layers exhibiting pronounced molecular recognition capabilities based on size, shape and preferably hydrogen bonding. Sensitive layers, often termed as synthetic antibodies, were generated by an innovative method of surface imprinting with bio-analytes. Atomic force microscopy (AFM) proved an excellent tool to examine the bio-imprinted polymer surfaces. Bio-imprinted layers, capable of reversibly absorbing the imprint species, opened up the possibilities to detect different types of cells, for instance, yeast and bacteria. Viruses such as the tobacco mosaic virus, the pox and the human rhinovirus, were specifically detected down to a few ng/mL. Furthermore, by imprinting with bio-analytes, the cross sensitivities can almost be neglected and distinguishing different biogeneous species becomes feasible. The synthetic antibodies yield a more characteristic response pattern than the natural ones. [ABSTRACT FROM AUTHOR]