City University team aims to develop portable drug sensors

After receiving follow-on funding from the EPSRC, the team is aiming to create commercially viable sensors that are capable of detecting multiple drugs.

The scientists have been working on drug sensors over the past three years and have so far managed to successfully develop an optical-fibre drug sensor capable of detecting cocaine.

Prof Tong Sun, project leader and an expert in sensor engineering at City University, told The Engineer that optical-fibre drug sensors are small and light, which makes them suitable for multi-drug detection.

‘Lock and key’

Sun said that the relationship between a sensor and a target molecule is like a ‘lock and key’. ‘We use the Molecular Imprinted Polymer [MIP] technique to create this relationship artificially,’ she said.

‘MIP is used to form a polymer sensor material [the “lock”] in the presence of a specific drug molecule [the “key”]. This drug is then extracted, leaving recognition sites — effectively “keyholes” that give the sensor material an affinity towards the drug.’

The sensor material is integrated into the overall sensor design along with a fluorophore. When the sensor interacts with the drug through the ‘lock-and-key’ effect, a chemical process triggers the fluorophore to emit a fluorescence signal. This signal is in turn picked up by a photodetector, which indicates the drug’s presence to the user.

The Home Office will provide the team with specific drug compounds that it wishes to detect.

Compact device

There are similar devices currently on the market, but Sun claims that these are still relatively big and bulky compared with the sensors the City University team is hoping to develop.

She explained that police officers would be able to carry a bundle of the tiny optical-fibre sensors in one compact device so they would be able to detect more than one drug.

Sun said the technique can’t be used to detect other potentially harmful substances at this moment in time. ‘I think sensitivity of the sensor may need to be enhanced before we can detect explosives,’ she added.

City University will be the only academic institution to work on the next stage of the project, which is being run in conjunction with the Home Office and Smiths Detection from April.