Tiny sensor can turn smartphones into a real pocket lab

21 Dec 2017

Image: Bancha Photography/Shutterstock

A tiny sensor has been shrunk down to fit into a smartphone and turn it into a powerful piece of lab equipment.

Smartphones of the near future will be able to scan a food item to see how fresh it is or check how clean the surrounding air is, following a new breakthrough by a team of engineers at Eindhoven University of Technology in the Netherlands.

In a paper published to Nature Communications, the team revealed its tiny, new spectrometer – a device that measures visible and invisible light, revealing a ‘footprint’ of every material and tissue.

While precise spectrometers are typically large devices because they split up the light into different colours and need to be measured directly, the Dutch team’s device takes measurements in a completely different way.

It does this using a special ‘photonic crystal cavity’ that acts as a ‘trap’ of just a few micrometres into which the light falls and cannot escape. Contained within a membrane, the catching of the light results in a tiny electrical current being generated, which is then measured.

Still some way to go

To amp it up to measure larger frequencies, the researchers placed two of their membranes, one above the other. The membranes influence each other and if the distance between them changes slightly, then the light frequency that the sensor is able to detect shifts, too.

Using a micro-electromechanical system, the distance between the membranes can be varied, thereby measuring the frequency at a wavelength range of 30 nanometres when it can discern about a hundred thousand frequencies, giving it exceptional accuracy.

This is made possible by the fact that the researchers are able to precisely determine the distance between the membranes to just a few tens of femtometres, a measurement equal to one-quadrillionth of a metre.

To show its usefulness, the team led by Prof Andrea Fiore showed that the device was capable of working as a gas sensor, as well as a precise motion sensor.

As for when we can expect such a precise sensor in smartphones, Fiore predicts it will be another five years or more as the frequency range it covers is still too small, at just the near-infrared range.

The next step for the team’s research is to extend the detectable spectrum as well as integrating the extra element of a light source with the micro-spectrometer, which will make the sensor independent of external sources.

Colm Gorey was a senior journalist with Silicon Republic