Swedish start up gives sensors cheap energy from indoor lighting

When we first began to write about the IoT, one of the ideas that fascinated us was harvesting physical movement and turning it into electrical energy, like pushing a light switch, and the pressure of your finger generating enough energy to power a wireless signal to speak directly to a bulb telling it to turn on – eliminating control wiring. This week we have come across Epishine, a company that has been working in taking Organic Solar Panels from the Norrkoping University lab in Sweden, into mass production. It is more a case of all devices getting re-charged while the light is on in a home, rather than harvesting physical energy to do that re-charging.

This issue here is that most solar panels which aim to be cheap focus on outdoor light, which needs to be sensitive to many different frequencies of light. For Sweden’s 15 man Epishine this is about taking far fewer frequencies, those present in light bulbs, and getting as much as they can out of that. They claim their materials can absorb close to 13% of the light that falls on them and turn it into energy – which is quite a remarkable achievement.

This week it seemed to have a breakthrough destined for supermarkets, with a new customer, another start up, TempOnline, which offers digital temperature monitoring for grocery stores. Between the two they plan to completely remove batteries from the sensors that track the temperature, and replace them with light sensitive capacitors, that re-charge when the lights are on. These are sensors which monitor temperatures in coolers and freezers.

Epishine is Swedish and came out of research carried out at Norrkoping University. At a typical in-home luminance of just 500 lux, the Organic Solar Panels will output of 20 Watts per square centimeter of material (see picture below). It’s great advantage over a battery is that at low temperatures long term IoT batteries which usually power sensors, lose much of their charge, whereas this power conversion still works down to minus 30 degrees centigrade. That makes it perfect for the supermarket freezer section, and future applications being considered include sensors which tell if doors and windows are open, powering bathroom scales, large clocks, and any indoor smart surface (up to 1 square meter).

A spokesman told us, “It costs around $1 per sensor right now, but once we manufacture in bulk the cost could come way down. This is like a printing process and we can put it on any surface.” The problems with Organic polymers is that they are volatile and combine with Oxygen in humid environments. They key to the Epishine system is the patents it holds in its manufacturing process using barrier plastics around the material, without affecting its light sensitivity. The system uses Pedot: PSS a polymer associated with preventing electrostatic discharges, and this application in electrolytic capacitors.

The TempOnline solution provides automated temperature monitoring on a subscription-based plan and so far it is through to have installed just 10,000 or so sensors. The new ones are powered by Epishine’s polymer.

Epishine CEO, Mattias Josephson, said, “With light energy harvesting modules, we now have a more sustainable and stronger offer, and we know that there is a great need for this in all businesses that handle food. Our solution means that they can eliminate manual temperature measurements of coolers and freezers.” The first prototypes were installed in early March at ICA Nära Marcus, a grocery store in Väderstad, Sweden.

Recently Epishine took 11.3 Swedish Krona in investment ($1.2 million) to create an automated polymer production line, in an investment that valued the business at just $6 million or so.

Epishine has developed a unique lamination process to produce solar cells that can generate electricity at extremely low light conditions. The production method uses organic materials and avoids expensive or toxic substances such as silver and arsenides.

Last month Epishine joined the EnOcean Alliance which is trying to accelerate the adoption of maintenance-free, energy-efficient devices and systems for intelligent buildings.

Look out for more and more of these applications, where the electricity to power a small device in the home or out and about, is distributed right down to individual devices, and cheap manufacturing processes.