The sensor, display and battery will all be based on inkjet printing technology to create a single-use, disposable device that should be easy and relatively cheap to manufacture.
‘Although there are tests at the moment just related to free cholesterol, one of the objectives of our programme is to bring that to the next stage of development in looking at assays specific for both LDL and HDL cholesterol, bad and good cholesterol if you will,’ said Tony Killard from the University of the West of England in Bristol.
The other collaborators include Liverpool and Dublin City universities, the Technical Research Centre of Finland and industrial partner Alere.
Killard’s team is responsible for the bioelectrochemical sensor, which uses a whole blood spot as input. It first uses the enzyme cholesterol oxidase to generate hydrogen peroxide, which can be detected with a silver-based surfactant to be converted into an electrical signal. That raw data is then analysed using the fledgling technology of organic electronic computing.
‘The ability of organic electronics to do good analogue-to-digital conversion is really not well developed — the idea you can think of organic electronics in a completely parallel way with silicon is probably not going to work — we have to think of clever solutions,’ Killard said. ‘Instead of going for a more complex segment display system we have a simple bar display that has a range of cholesterol concentrations.’
This display uses electrochromic technology rather than more complex expensive OLEDs. In addition, the data can also be transferred to a smart phone for wireless communication to healthcare professionals. The system is powered by a thin battery that uses printable electrolyte materials.
‘There are a whole series of materials compatibility issues that need to be solved, and also process compatibility issues. For instance, the biologicals and enzymes that we are using, they would be one of the very last layers to be deposited through printing, any of the other harsher processes would already have taken place,’ Killard said.