VTT's printing-based techniques enable mass-producible products at low price. In addition, the ability to use biodegradable materials in the printing process enables power sources that are fully disposable and environment-friendly. Printed electronics with an integrated power source have remarkable market potential in several mass-market consumer product areas. There is currently a substantial emerging market for specialised disposable electronics-containing products such as 'smart' patches and drug delivery systems in medicine and cosmetics. For many applications, the power source must be biodegradable or able to be incinerated with normal household waste. Production costs should also be reasonable. The power sources described have the potential to be developed to meet these demands.
Printable power source alternatives - bio-battery and supercapacitor
Enzyme-catalysed bio-batteries are fuel cells capable of transforming the chemical energy of the fuel directly into electrical energy via electrochemical reaction. The energy source can be, for example, glucose. The electrochemical reactions inside the biobattery are catalysed by enzymes, enabling reliable operation of the cell under mild conditions and the utilisation of various renewable chemicals as fuels. Prior to use, the electrodes of the VTT bio-battery can be stored in a dry state for weeks or even months; then, after activation with moisture, the battery is able to generate power for several days.
A supercapacitor is an electrochemical energy storage component. The power density of supercapacitors is typically 10-fold compared to Li-ion batteries, and their cycle-life can exceed one million cycles. The drawback of supercapacitors compared to batteries is that their energy density is considerably lower. VTT produces supercapacitors using an unconventional method – printing.
VTT has demonstrated the R2R processability, including drying, of the biologically active materials and the manufacturing of anodic and cathodic layers by means of rotary screen printing on VTT's pilot-scale roll-to-roll printing line. VTT has also manufactured activated carbon electrodes for supercapacitors using rotary screen printing on various laminate substrates, such as aluminium on PET and aluminium on paperboard.