Microsensors and Nanosensors

Sensors are systems or devices that provide signals, which are correlated to some physical, chemical, or biological condition in their neighborhood. The signals can be transformed, by use of a calibration curve, into information about the environment of a sensor. There are two classes of sensors, point sensors that provide information only from their immediate surroundings and volume sensors (imagers or cameras) that can give information on conditions in an extended region. Sensors are old, but recent advances in miniaturization technologies have been leading to very small and capable sensors. Micromachining processes, which grew out of the microelectronics industry, have been used for about two decades to make microelectromechanical systems (MEMS) that are relative cheap and extraordinarily reliable. Microsensors for pressure and acceleration are now sold by the tens of millions annually. In the past decade, processes have been developed to grow nano-materials, which have structures on the scale of molecules. They are proving to be very useful for small sensors, especially for chemical and biological applications. Two-dimensional arrays of bio-sensors, based on DNA or antibodies to recognize the target molecules in a sample, are especially important. They, and other small sensors, enable almost immediate diagnostics at the point of care, rather than sending samples to a central laboratory. Small sensors make it possible to put diagnostic equipment inside the body. They are expected to have an increasing impact on biomedical engineering and clinical medicine. Keywords: sensors; microsensors; nano-sensors; microtechnology; nano-technology; chemical sensors; bio-sensors; clinical medicine