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Abstract We describe the concept and roadmap of an engineered electronic nose with specificity towards analytes that differ by as little as one carbon atom, and sensitivity of being able to electrically register a single molecule of analyte. The analyte could be anything that natural noses can detect, e.g. trinitrotoluene (TNT), cocaine, aromatics, volatile organic compounds etc. The strategy envisioned is to genetically engineer a fused olfactory odorant receptor (odorant receptor (OR), a membrane-bound G-protein coupled receptor (GPCR) with high selectivity) to an ion channel protein, which opens in response to binding of the ligand to the OR. The lipid bilayer supporting the fused sensing protein would be intimately attached to a nanowire or nanotube network (either via a covalent tether or a non-covalent physisorption process), which would electrically detect the opening of the ion channel, and hence the binding of a single ligand to a single OR protein domain. Three man-made technological advances: (1) fused GPCR to ion channel protein, (2) nanowire sensing of single ion channel activity, and (3) lipid bilayer to nanotube/nanowire tethering chemistry and on natural technology (sensitivity and selectivity of OR domains to specific analytes) each have been demonstrated and/or studied independently. The combination of these three technological advances and the result of millions of years of evolution of OR proteins would enable the goal of single molecule sensing with specificity towards analytes that differ by as little as one carbon atom. This is both a review of the past and a vision of the future. 

In this paper we present a simple method to demonstrate quantum sensing of magnetic fields with nitrogen vacancy centers in diamond using an off the shelf, commercial confocal and super resolution (Airyscan) microscope and a microwave generator. The measurement is based on CW (continuous wave) optically detected magnetic resonance (ODMR). The noise is empirically analyzed. This should give a good indication of what labs can expect with readily available microscopes in any modern university setting.