The wide appliance of sensor science

The latest research on sensors crosses the scientific divides, and offers a staggering array of practical applications

IT IS DIFFICULT to find a more interdisciplinary research subject than sensors. The latest generation of sensors integrates physics, chemistry, biology, engineering, information technology, nanotechnology, microfluidics and biotechnology, to name just a few.

All these disciplines come together in research work conducted at the US Naval Research Laboratory (NRL) in Washington, according to the lab's senior scientist for biosensors and biomaterials, Dr Frances Ligler.

These sensors combine biologically active molecules and specially designed hardware to deliver small devices that can detect anything from environmental pollution and biowarfare agents to explosives and whole bacteria, Dr Ligler explains.

She delivered a keynote address on biosensors last Monday at Dublin City University, where some 300 of the world's leading optical biosensor and optical chemical sensor research scientists gathered for the ninth annual Europtrode conference.

Held biennially, Europtrode is the largest optical sensor meeting in the world, states Prof Brian MacCraith, the director of DCU's Biomedical Diagnostics Institute, who co-chaired the event with institute colleague, Prof Colette McDonagh.

The four-day event included no fewer than 248 individual presentations and 20 plenary and invited speakers. Delegates heard about the latest research and Dr Ligler talked about a number of projects in her lab and the devices arising from them.

"My goal was to give people an idea of all the skills needed to bring research to bear and the need for user involvement," she explains.

Her work with colleagues has led to 24 patents on technologies that are already being commercialised by companies. The US government actually owns the patents, given that they arose from work at the NRL, the US navy's Washington-based "corporate laboratory". The lab employs almost 2,500 people and conducts a broad programme of scientific research and development.

The approach taken to develop a new sensor depends on its chemical or biological "target", who will use it, and how it will be used, Dr Ligler says. "There are lots of different ways to do it."

Biological or chemical molecules are integrated with hardware devices that deliver an optical signal if the target substance is present. The first-generation sensors were based on optical fibres and those that followed incorporated chromatography.

Microarrays, which can test for thousands of proteins in a single sample, represent third-generation technology and the latest fourth-generation devices rely on flow cytometry.

"We are developing the systems to test for dozens of different targets simultaneously," Dr Ligler explains. This can be done on a sample-by-sample basis or as a continuous flow, with the systems doing their own analysis and interpretation.

"The trick is to adapt the right technology to the right application. We are developing a whole new toolbox of approaches. It is a very exciting area to work in."

The range of possible applications for these advanced devices is staggering. They can be used to test blood or fluid samples for drugs, or to measure toxic chemicals or pollutants. They can be used to characterise an environment, for example, to sample substances present in the upper ocean layers, which serve as a sink for atmospheric carbon.

Staff working with Dr Ligler tend to break into small groups of from five to 15 scientists, with the skills mix a reflection of the specific requirements of the project. "The type of people who are needed tends to change as a project matures," she says.

More information is available from DCU's Biomedical Diagnostics Institute website, www.bdi.ie, and from the Europtrode website, www.europtrodeix.eu