Printed Bioelectronics

This lecture will consider how the recent emergence of printed bioelectronics can offer new solutions to distributed diagnostics for the maintenance of wellbeing, management of an ageing population, food security and environmental safety. The adaptation of screen printing for the production of enzyme electrodes proved to be a decisive element in the success of mediated electrochemical devices in the home blood-glucose monitoring market. Until then, biosensors had been wholly hand made, and could not possibly address a market requiring billions of devices a year. Coupled with the use of proprietary mediators and patented capillary-fill designs, machine fabrication of enzyme electrodes enabled the paradigm changing switch to the electrochemical devices that now dominate this market. Today, approximately half of the electrodes used in disposable glucose sensors are screen printed using curable polymer inks, while the remainder are produced using a combination of vapour deposition of thin layers of metal such as palladium, followed by laser ablation to pattern these into individual electrodes. Additional printing steps, drop-on-delivery and /or lamination results in a final sensor, which can cost around 2-6 US cents / strip to make, when produced by the millions. However, it is now timely to challenge our original paradigm of a disposable strip coupled to a pocket-sized meter. Even in bulk, the average meters cost between US$7-10 to manufacture, with some more elaborate versions costing as much as US$90. So why not print the whole device? All-printed Mn –ZnO batteries can already be made to power microsensors and for other applications such as RFID tags, transdermal drug delivery, cosmetic patches and smart packaging. These are available as commercial products such as the SoftBattery™ from Enfucell (Finland). Monochrome emissive or reflective digital displays can be printed on both paper and plastic and, in keeping with the trend to interface biosensing systems with telecommunication, thin film aluminium or copper ...