Readout method for pathogen detection using biosensor

A biosensor consists of biologically sensitive material used in close conjunction with a device that will convert a biological reaction into a quantifiable electrical signal. Biosensors have many advantages, such as simple and low-cost instrumentation, fast response times, minimum sample pretreatment, and high sample throughput. This biosensor based on piezoelectric crystal can be used for pathogen detection. In this work Quartz crystal microbalance QCM is used as a biosensor. The quartz crystal or resonator operates due to the piezoelectric effect. Electronic circuit system that can be used to realize a QCM biosensor consists of an oscillator and a frequency counter. A 10 MHZ Quartz crystal is used to produce oscillations. The resonant frequency of an oscillating piezoelectric crystal can be affected by a change in mass at the crystal surface. Piezoelectric immunosensors are able to measure a small change in mass. Crystal surface has to be coated with antibody specific for a disease. An antibody (Ab), also known as an immunoglobulin (Ig), is used by the immune system to identify and neutralize foreign objects such as bacteria and virus. The antibody recognizes a unique part of the foreign target, called an antigen. Antibodies are proteins produced in the blood in response to the presence of an antigen. The blood sample should be introduced on the crystal and if the sample contains the disease causing antigen, reaction between antigen and antibody takes place. This reaction causes a change in mass on the crystal surface there by the resonant frequency of the crystal is changed. This shift in frequency is measured by the frequency counter. The material for immobilization of biomolecules on its surface is selected according to its properties.