Opto-acoustic sensing for on line chemical process measurement

Supervisor: Dr Theodosia Stratoudaki 

The aim of this research will be wireless, battery free, remote, optically excited ultrasonic sensors. As a result, they will have minimum impact on structures, will be electrically neutral and could be applied remotely even in hazardous or sterilised environments or in places with limited access. Conventional, piezoelectric based, Surface Acoustic Wave (SAW) devices have been used as temperature sensors, gas sensors, humidity sensors, pressure sensors and strain gages. Their shortcomings are the delicate electrical connections and packaging design especially when they are used as biosensors. Optical based SAW sensors can address these issues and using them for chemical sensing will also open the door to environmental, healthcare and biomedical applications.

The opto-acoustic SAW sensors will be based on laser ultrasonics, which is a technique that uses laser to generate and detect ultrasound. This makes the technique completely remote, addressing extreme environments or places of restricted access. During this PhD/EngD, these sensors will be firstly used for detection in gas and liquid phase. Secondly, there will be a construction of an array of sensors using different chemosensitive films and light delivery through optical fibres. Applications include differentiation of liquids based on their volatile compounds (e.g. wine) or measuring antibody-antigen interactions (biosensors). The anticipated research outcome will be optically excited SAW based sensors with the possibility of observing real-time chemical events at relevant sensitivity levels and at low cost, since the sensor is in no contact with the sensing environment and can be used many times.