"This is a fascinating device," said Vikas Berry, UIC associate professor and principal investigator on the study. "Here we have a biological entity. We’ve made the sensor on the surface of these spores, with the spore a very active complement to this device. The biological complement is actually working towards responding to stimuli and providing information."

By applying graphene quantum dots (GQDs) to such a micro-organism, various quantum-mechanical effects like electron-tunneling, optical-blinking, and a range of mechanical and sensing functions may be integrated. In the UIC case, the GQDs used were configured to take advantage of the controllable trans-membrane hydraulic transport – the spore’s ability to eject water – to act, in this case, as an electro-biomechanical humidity sensor.

"We’ve taken a spore from a bacteria [sic], and put graphene quantum dots on its surface – and then attached two electrodes on either side of the spore," said Berry. "Then we change the humidity around the spore. When the humidity drops, the spore shrinks as water is pushed out. As it shrinks, the quantum dots come closer together, increasing their conductivity, as measured by the electrodes. We get a very clean response – a very sharp change the moment we change humidity."

The researchers also documented that the response was approximately 10 times faster than artificial humidity sensors currently manufactured, even with the best synthetic water-absorbing polymers known. They noted, too, that the electro-biomechanical device that the team created appeared to have improved sensitivity in exceptionally low-pressure, low-humidity environments compared to the artificial sensor.

The practical upshot of this work, according to the researchers, is that it may exploit the unique biomolecular structure of micro-organisms in a way that achieves both controlled nanoscale architecture and membrane transport for micromechanical actuation. This, then, could be applied to a wide range of fields including, cellular control, microbotics, biochemical analysis, targeted molecular or ionic detection, as well as implants for biological monitoring.

David Fuller's view

Accelerating technological innovation is taking place with previously unimaginable speed.  This is fascinating, and more importantly, extremely useful.  This is the exciting future that we face in developed economies, not the gloom that we hear from financial pessimists.