Biosensors are analytical devices used to detect a biological component using a recognition element (bioreceptor), transducer, and processing/display element. Biosensors are used in many different fields for a variety of applications, from blood glucose monitoring to the detection of airborne bacteria from a biological attack. But what actually makes up a biosensor?
The Recognition Element
This is the first major component of the biosensor. Its purpose is to bind with specific elements in the sample (blood, urine, saliva). If an antigen is to be detected, an antibody will be used as the recognition element. If a substrate is to be detected, than an enzyme will be used as the recognition element. Nucleic acid and cells are two other, less used, recognition elements.
The biosensor component measures the binding of the recognition element with the specific element in the sample. Electrochemical, electrical, piezoelectric, thermometric, and optical are all popular types of transducers. Electrochemical reads currents produced by the binding. Electrical measures changes in resistance due to binding. Piezoelectric measures the change in mass due to the binding. Thermometric measures the change in temperature due to binding. Optical measures the changes in optical intensity due to binding.
The Display/Processing Element
Lastly is the display and processing element. This element connects to the output of the transducer, possibly through an amplifier depending on signal strength. The goal of this element is to take a signal and extract any useful information from it. Once processed, it is sent to the display. For example, this step will displays a patients readings and display if they have cancer or not.
Microfabrication is the process of fabricating miniature structures of micrometer scales and smaller and is used to manufacture items such as integrated circuits (ICs), microelectromechanical systems (MEMS), solar cells, etc. The major processes of microfabrication include lithography, doping, etching, bonding, and polishing.
At LeTourneau, the students use the following to produce the microfabrications:
LASI (LAyout System for Individuals) is a general purpose layout and design software originally intended for integrated circuits. It is versatile enough that it can be used for ICs, MEMS, other nanotechnologies, discrete devices, schematics, PC boards and project documentation drawings.
Photolithography is an optical method of transferring patterns onto a substrate, and it is a binary pattern transfer meaning that there is no gray-scale, color, or depth to the image. Below is the basic process used in photolithography.
Sputter deposition is the process of depositing thin layers of material such as gold, ranging from fractions of a nanometer to several micrometers in thickness, onto a substrate. It is used extensively in the manufacturing of ICs in order to deposit thin films of various metals. A gaseous plasma is created. Ions are accelerated from the plasma into the material. This erodes the material ejecting atoms in a straight line, coating the substrate.