Peter Wu

Chapter 5 – The Role of Direct Writing For Chemical and Biological Materials: Commercial and Military Sensing Applications

The processing of materials for chemical and biological sensing applications by direct-write techniques is complementary to the micromachining developments that impact the form factor of a broad range of applications including chemical and biological sensors, and microwell related technologies. Chemical-sensor applications utilize cross-reactive arrays in which different sorbent materials are coated to offer array selectivity to a range of analytes. The arrays of biosensors are needed to monitor different analytes, because individual sensor elements are highly selective. There are several driving forces pushing for sensing device miniaturization–– namely, smaller system size, increased analytical throughput, conservation of analyte and support materials, increased ruggedization and quality control, and the option for disposable arrays. Large arrays of sensor elements are achieved by using micromachined miniaturization of sensor arrays. The dense array formats favor direct-write techniques. Typical sensor arrays involve around 10 sensor elements, future array sizes are designed to utilize thousands of different coated elements. Microwell plate technologies developed for high-throughput pharmaceutical screening and diagnostics or combinatorial synthesis applications, produces arrays of 9,600 plates.