Detection and quantification of pathogenic bacteria using giant magnetic resistance sensor

Abstract

Clinical diagnosis of bacteria is very important. Currently there are many methods like ELISA (Enzyme Linked Immunosorbent Assay), PCR based method (Polymerase Chain Reaction), optical method and various other methods used for detecting the bacteria. ELISA and PCR based method takes more time for producing the results. The optical method suffers from the high background noise caused by stray light. Thus there is need for developing a device that is cheap and more sensitive. The magnetic sensing device is the best candidate to meet this criterion. Giant magnetic resistance (GMR) sensor is cheap, small and sensitive when compared to the other available magnetic sensors. Here the bacteria are tagged with Fe2O3 magnetic nano particles of size 40nm coated with suitable antibody. When external magnetic field is applied to the magnetic nano particles it will produce a local magnetic field and this magnetic field will cause change in the resistance of the GMR sensor. Thus by detecting the quantity of magnetic field produced by the magnetic nano particles the amount of bacteria in the sample can be quantified. The aim of the paper is to design a cost effective device that can sense the bacteria in the sample. Here the experimental setup has been designed and tested with different functionalized magnetic nano particles immobilized on the GMR sensing surface and applying the magnetic field in the z-axis direction.