Working Principle of Biosensors
A biosensors consists of (i) a biological component for sensing the presence and concentration of a substance and (ii) a transducer device, which works according to the principle shown in. The smaple is allowed to pass through a membrane so that selection may be exercised and the interfering molecules are retained outside the membrane. The sample then interacts with the biological sensor and forms a product, which may be an electric current/charge, heat, gas or a suitable chemical. The product then passes through another membrane and reaches the transducer, which converts the biochemical signal into an electrical signal that can be further amplified and can be either read on digital panel or can be recorded over recorders.

This allows the measurement of the concentration of substrate without processing and thus avoiding consumption of the sample. Some details of biological sensing elements, and transducers used in biosensors are summarized in Table.