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Home > News > Company News > 2D position and pressure senso.....

2D position and pressure sensor, from matchbox to room-sized

  • Author:Ella Cai
  • Release on:2017-10-23
Yorkshire start-up Quantum Technology Supersensors has been set-up to exploit a pressure-sensing technology that can produce 2D position sensors the size of a room, down to tiny touch pads.

Referred to as QTSS, it is based electron-tunnelling between shaped particles of ‘magnetite’ buried in various elastomers.

If this sounds familiar, company founder David Lussey also founded Peratech, whose technology is QTC – quantum tunnelling composite.

“QTSS is not dissimilar to QTC in that it relies on a composite material. Like QTC, tunnelling is promoted by the shape of the microscopic particles embedded in a polymer,” Lussey told Electronics Weekly. “Peratech’s intellectual property covers specific shapes of material to produce the tunnelling effect, and not magnetite.”

Lussey’s new material came out of experiments in his home lab after retiring from Peratech.

“I was looking at magnetite, which has many forms, and found one or two with particle shapes I had not seen before, which had interesting qualities,” said Lussey. “It senses well, with less electrical noise than QTC as it deflects.”

Low electrical noise he puts down to the physical characteristics of magnetite, although exactly what is as yet a mystery. “I am an engineer, not a scientist,” said Lussey.

So far, he claims to have created materials that cover 16 orders of resistance – covering both squashed and un-squashed forms. For example one material varies from 10^9 ohm relaxed  to “well below 1ohm” when compressed,” he said. “I have a material that detects when you blow on it, and one you have to jump on”

And jump on it you can, because it can easily be made over large areas – Lussey produces 2 x 2m sheets.

To turn add position sensing to an area pressure sensor, resistive area conductors are placed on either side of the QTSS sheet, with perhaps 10kohm from edge to edge. On one side, long electrodes are run across opposing edges – the north and south ends, as it were – while the other side gets electrodes across the east and west ends.

This results in a four-wire connection to the sensor, through which both the point of contact and the magnitude of contact can be deduced.

“With four wires, you can get real accuracy – people find it hard to believe it when they see it,” said Lussey. “On a 100 x 100mm 2D sensor, we can easily put a qwerty keyboard on it and register the centre of every key. It probably has ten times more resolution than you need for a keyboard. With a big sheet, you can see people walking across, and tell a large person from a child.”

As the system registers the point of highest force, someone standing on a sheet can shift their weight to mover e cursor – something akin to a human joystick, said Lussey. Or, he said, a sheet of it on the back of a phone can act as a joystick whilst viewing the front.

A version in the shape of a shoe insole has been made, that can be used to track the point of maximum load as it moves during walking for gait analysis.

The QTSS can be made by moulding, and a printing ink is under development – the firm is based at the Centre for Process Innovation (CPI) in Sedgewick, which was set-up to print active materials.

Surface electrodes can be carbon-loaded textile or carbon-loaded polymer or printed carbon-loaded film.

What about temperature?

“Temperature plays some part, but it is not dramatic,” said Lussey. “In terms of room temperature, you can forget about it.”

Magnetite is a stable iron oxide, so no spontaneous decomposition, nor excessive chemical sensitivity is expected.

One potential application is passenger assessment for car airbags – is it a child or adult sitting in the seat?

Can it last the 10-15 year life f a car? “With what I know now, without a doubt, it will last if you pick the right polymers,” said Lussey.