Systematic approaches for biodiagnostics using exhaled air.

The 21st century is witnessing a revolution in understanding the composition of human exhaled breath more deeply, as the "breathe-print" can provide significant information of various diseases and disorders. This review elucidates various breath analytical techniques applied in medical diagnosis. A quick, portable, simple, accurate, non-invasive and relatively inexpensive approach of this technique is the reason of its evolution as a new frontier in disease diagnosis. This review emphasizes on breath biomarkers and traditional approaches in techniques used for breath biosensors like GC-MS, SIFT-MS, PTR-MS, IMS, Optical Absorption, Sensor Arrays and Electronic noses along with other new approaches such as Enzyme Immunoassay, Fluorescent Bead Immunoassays, Polymerase Chain Reaction, Antibody Microarray. It also includes the approaches using nanotechnology to improve the sensitivity and portability of breath biosensors. Still there is a lack of sensitive, standardized and accurate technique for the validation of biosensor. Hence future research is needed to overcome the loopholes in the present techniques.