Sense of purpose

Written by: Written by Lou Reade | Published:

An optical sensor chip is moving away from bio-terrorism and, quite literally, into the field. Lou Reade reports

A sensing technology that started life as a way of fighting bio-terroriwm could soon be used in a test for foot-and-mouth disease.
Spectrosens – an optical sensor chip developed by Southampton University spin-off Stratophase – will form the basis of a £1m project to develop such a test.
The project’s other partners include the University of Cambridge, Bristol Industrial and Research Associates Limited (Biral) and Chelsea Technologies Group. The work is part-funded by the Technology Strategy Board.
The new system should enable inspectors, and ultimately vets or farmers, to identify the infection on the spot.
The collaborative project will bring together teams from Stratophase, the University of Cambridge, Bristol Industrial and Research Associates Limited and Chelsea Technologies Group. It should be more sensitive and accurate than existing field-deployable systems, and much faster than laboratory-based techniques.
The system will collect pathogens from the air and put them into a liquid stream. The liquid will then be analysed ‘in the field’ using the Spectrosens detectors. When a specific pathogen sticks to the surface, the chip undergoes a tiny optical change.
Devaki Bhatta, project leader from Stratophase, said: “The ability to collect and identify airborne pathogens will remove the need for swabs and blood samples. This project is to develop a foot and mouth detection unit but could be used to identify TB and a range of other serious illnesses that affect livestock.”
One year ago, a German university began a project to assess the chip’s suitability for a range of applications.
The first complete sensing unit based on the technology was chosen by the University of Applied Sciences at Aschaffenburg for a three-year research project. Aschaffenburg believes the technology could have widespread commercial application in food, beverage and pharmaceutical manufacturing industries, drug discovery and process control. It will investigate how to combine the technology with microfluidic structures to create a robust, cost-effective biochemical sensor for commercial use.
Stratophase’s technology detects toxins, viruses and bacteria in real time. It has an optical silicon chip with an integral planar Bragg grating, using a fibre-optic cable to transmit light to the chip. When contaminants are carried in liquid across the surface, tiny changes in composition can be detected by precise, continuous monitoring of the wavelength of light reflected from the sensor. The surface can be pre-treated to make it sensitive to certain biological or chemical reactions.
The university’s Dr Ralf Hellmann said: “As a purely optical process, it relies on changes in the refractive index on the surface of the sensor. This eliminates the usual and costly complication with other technologies of preparing the liquid specimen with fluorescent tags.”

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