7 November 2012 – Printed electronics is an enabling technology that helps make energy harvesting (EH) solutions ubiquitous. It will achieve this by offering a toolkit for designing elegant networked EH solutions compatible with diverse operating environments. This toolkit will encompass every element of printed electronics, including conductors, RFID tags, batteries, sensors, logic and memory, solar cells, etc.
EH refers to a system of devices that are capable of scavenging, storing and transmitting energy sources that would otherwise have simply been lost. These systems are designed to recycle lost ambient/background energies stemming from solar irradiation, temperature gradients, mechanical vibration, etc.
Of course, EH solutions can make a system more energy efficient, but their overall impact here will remain curtailed by the limited power output per device (often in the microwatt range). Their major value is in enabling self-powered networks of electronic devices and sensors, and in expanding the reach of electronic functionality to areas previously not possible.
EH solutions can deliver value in a diverse range of markets. These include the healthcare industry in which they can enable embedded distributed health monitoring systems; the building and infrastructure industry in which they can enable the real-time health and integrity monitoring of structures; the consumer electronics industry in which they enable extra portability by helping mobile devices self-power amongst many others.
The value of networks scales with the numbers of nodes, thereby emphasising high production throughput and low cost. The power output of some classes of energy harvesters scale with area, thereby emphasising large-area electronics. The utility of EH solutions is often in adopting to curved or irregularly shaped substrates thereby emphasising form factor. Printed electronics is an enabling technology that helps realise all these attributes.
Printed electronics already offer an exciting toolkit for implementing EH solutions. This toolkit covers all essential elements of an EH system. Indeed, a diverse array of harvesters can be printed; organic photovoltaics and dye-sensitized solar cells can be printed to utilise solar energy, particularly from indoor lighting sources; printed piezoelectric scavengers can be used to harness vibrational energy; printed thermoelectric devices can exploit temperature gradients, for example.
Flexible and thin batteries can also be printed and store the scavenged energy. This functionality is particularly useful in cases where the energy source is cyclical, experiencing intense peaks followed by prolonged low levels of activity. Printed electronics can also enable networking between individual energy harvesters (or functional nodes in the system powered by energy harvesters). This is because RFID antennas and chips (logic and memory) can also be printed, roll-to-roll. Even flexible sensors can be printed, over large or small areas, allowing the EH systems to monitor temperature, strain, heart beat rate, vibration, light flux, etc.
Printed electronics allows EH solutions to be directly integrated onto the end products, regardless of their shape or fragility. This is because devices can be deposited using non-contact inkjet-printing. Printing even makes the end solution more elegant by simplifying the wiring. This is because all manners ofconductors can now be printed, satisfying different conductivity, cost or thermal budget requirements. Indeed, additive printing process will be a major driver because they enable the manufacture of flexible, thin, large-area devices at low cost and high throughput.