ionic liquids

Diabetic sweatbox

A wearable device that monitors compounds in your sweat for up to a week could help in the early detection of diabetes, according to the University of Texas, USA, research team.

The wearable device, pictured above, can detect cortisol, glucose and interleukin-6 – interconnected compounds linked to diabetes – in perspired sweat. ‘If a person has chronic stress, their cortisol levels increase, and their resulting insulin resistance will gradually drive their glucose levels out of the normal range. At that point, one could become pre-diabetic, which can progress to type 2 diabetes,’ said Dr Shalini Prasad, Professor of Bioengineering.

Not only is the Texas team’s device functional for one week without loss of signal integrity, it requires a far smaller degree of sweat – one to three microlitres, rather than 25 to 50 – to be effective. Prasad said, ‘We spent three years producing that evidence. At those low volumes, the biomolecules expressed are meaningful. We can do these three measurements in a continuous manner with that little sweat.’

The team’s paper, A new paradigm in sweat based wearable diagnostics biosensors using Room Temperature Ionic Liquids (RTILs), can be read on Nature.

Your next electronic device could last double the time

Credit: SolidEnergy Systems

A spinout company of MIT, USA, has produced a new rechargeable lithium metal battery that can double the energy capacity of lithium-ion batteries and could make smartphones, drones and electric cars last twice as long.

The company behind the design, SolidEnergy Systems, developed the anode-free lithium metal battery by replacing a common battery anode material, graphite, for very thin, high-energy lithium-metal foil, which can hold more ions to increase energy capacity.

Hu, co-inventor and CEO of SolidEnergy commented, ‘With two-times the energy density, we can make a battery half the size, but that still last the same amount of time, as a lithium ion battery. Or we can make a battery the same size as a lithium ion battery, but now it will last twice as long.’

Hu developed a solid and liquid hybrid electrolyte solution. He coated the lithium metal foil with a thin solid electrolyte that doesn’t require heat. He also created a quasi-ionic liquid electrolyte, which proved inflammable, and has additional chemical modifications to the separator and cell design to stop it from negatively reacting with the lithium metal.

The final result was a battery with energy-capacity perks of lithium metal batteries, but with the safety and longevity features of lithium ion batteries able to operate at room temperature. ‘Combining the solid coating and new high-efficiency ionic liquid materials was the basis for SolidEnergy on the technology side,’ adds Hu.

The chemical modifications to the electrolyte allow the lithium metal batteries to be rechargeable and safer to use. The SolidEnergy has now moved into bigger space and Hu is hoping to ramp up production for their November launch.

Liquid salts by-pass skin to treat infection (Nature News) Liquid salts can improve the treatment of skin infections by killing bacteria and enhancing antibiotics’ ability to penetrate the skin’s outer layer, a new study finds. A team led by Samir Mitragotri, a chemical engineer at the University of California, Santa Barbara, has demonstrated this strategy in principle in a study published this week in Proceedings of the National Academy of Sciences1.

After tests for skin toxicity and irritation, one ionic liquid — choline geranate — emerged as a multipurpose vehicle, showing antimicrobial activity, minimal toxicity and enhanced delivery of the broad-spectrum antibiotic cefadroxil.

The researchers then tested the effectiveness of choline geranate as an antibiotic-delivery vehicle in an in vitro skin model that was wounded and infected with biofilm-forming Pseudomonas aeruginosa. Less than 5% of the bacteria survived when the antibiotic ceftazidime was paired with choline geranate, compared with 80% when the antibiotic was used on its own.

Dental plaque is a biofilm that forms on teeth. David Scharf/Corbis