Optimising of the sensing chamber of an array of a volatile detection system

A fluid dynamic analysis was performed to optimise the positioning of sensor elements in a coated quartz crystal microbalance (QCM) based volatile detection system. The computational fluid dynamic (CFD) code used solves the Navier-Stokes equations statically and dynamically in 2D, discretised by finite elements. In the original sensor chamber, the sensor elements were positioned in a staggered pattern and at 90° to the incoming flow. The numerical analysis shows that, with the exception of the front face of the first sensor, only 45% of the flow passed over the sensors. It is shown that the response of sensor elements is strongly dependent on the sensor position. An optimised sensor chamber design was developed where the sensors are at 0° to the flow direction and a baffle plate diffuses the flow evenly over the sensor elements. The sensors are shown to receive the same flow and respond identically irrespective of position.

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