Smallest possible olfactory biosensor
Elementary chemistry defines how small a biosensor can be. A single bio-molecule sensor is the ultimate limit in miniaturisation. Using the electrical properties of single olfactory receptors, the SPOT-NOSED project partners have succeeded in actually fabricating a nano-sized sensor. A grid of sensors has been developed for enhanced accuracy and sensitivity. At the heart of such a sensor is the single receptor molecule. SPOT-NOSED project partners chose olfactory receptors for which at least one ligand was known. The receptors identify odours electrochemically by binding to a volatile ligand and sending a corresponding signal. A really challenging task was then to manufacture nanoelectrodes that will enclose the receptor and transmit the resulting signal to the operator. With the resulting micro-electrochemical cell, a micro transducer has been formed that detects changes in the receptor's electrical properties once an odour is detected. A stable monolayer of nanosomes was also formed that contains the receptors. For completion of the sensor as a whole two more steps were required. First, a signal amplification electronic circuit and then an interface for the final data acquisition and processing. Moreover, the SPOT-NOSED project partners have developed the necessary software to control the instrumentation for electrochemical measurements. A biosensor of this magnitude of sensitivity is capable of detecting changes of nanoscale magnitudes. The resulting olfactory sensor is a fine example of a fruitful collaboration between multi-disciplinary scientific fields and an asset soon to be fully exploited.
