Tricorder finds earthly applications

researchers have created a handheld sensing system its creators liken to Star Trek's ‘tricorder’ used to analyse the chemical components of alien worlds. But the system could have down-to-earth applications, such as testing foods for dangerous bacterial contaminants including salmonella, which was recently found in a brand of peanut butter in the US.

The new portable system is an ultrafast chemical-analysis tool that has numerous promising uses for detecting everything from cancer in the liver to explosives residues on luggage and ‘biomarkers’ in urine that provide an early warning for diseases.

The instrument is a miniature mass spectrometer combined with a technique called desorption electrospray ionisation, or DESI. The device and technique were developed by a team of researchers led by R. Graham Cooks, a Professor of Analytical Chemistry at Purdue's College of Science.

‘Conventional mass spectrometers analyse samples that are specially prepared and placed in a vacuum chamber,’ Cooks said. ‘The key DESI innovation is performing the ionisation step in the air or directly on surfaces outside of the mass spectrometer's vacuum chamber.’

Unlike conventional mass spectrometers, which are cumbersome laboratory instruments that weigh more than 136kg, the new handheld device weighs less than 9kg and can be used in the field.

‘We like to compare it to the tricorder because it is truly a handheld instrument that yields information about the precise chemical composition of samples in a matter of minutes without harming the samples,’ Cooks said.

The researchers at Purdue look for compounds that indicate the possible presence of a particular substance, such as cocaine or explosives residues. If these indicators are found, the equipment performs a more in-depth analysis to determine the exact chemical structure.

The research team has used the device to analyse clothes, foods and tablets, and to identify cocaine on $50 notes in less than one second.