Bipolar transistor for pH biosensors

Bipolar junction transistor (BJT) based pH sensors of high sensitivity and resolution and fast response time. A sensor is a transducer that receives and responds to a signal or stimulus from a physical system. It produces a signal representing information about the system, which is used by some type of telemetry, information or control system. Specifically, a biosensor is a device that contains a biological, or bio-inspired recognition layer with unique specificity towards target analytes, which can be pH, DNA, proteins, and small molecules like glucose, chemical warfare agents or environmental pollutants. The focus on electrochemical sensors and biosensors is growing exponentially, as these detection systems can be easily miniaturized and mass-produced for point-of-care applications. Electrochemical sensors are significantly impacted from the choice of the transducers characteristics. Field effect transistors (FET) have been widely used as transducers in electrochemical sensors for over 40 years. However, a completely new discovery has been made in this field, using a bipolar junction transistor (BJT) as transducer instead of a Field Effect Transistor (FET). The goal of this work is to use this type of device for the analysis of different analytes, in particular alcohol and sodium chloride solutions. Particularly in this internship, the sensor will be added to an array of sensors to be placed inside the artificial nose which is being developed at IBM's headquarters in Almaden.