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Supercapacitor provides energy for the Internet of Things

The Internet of Things spreads electronics to new and unforeseen places. When batteries cannot be used, where can electronics get their energy? As part of her doctoral thesis, Suvi Lehtimäki developed an inexpensive and adaptable supercapacitor for energy harvesting and storage.

As the Internet of Things grows, so does the need for new kinds of energy sources for the scattered electronics. Using rechargeable or replaceable batteries is not always an option, such as in monitoring the temperature of packaged foodstuffs during transport or in measuring the humidity of internal structures in buildings. Electronic devices, such as sensors and their transmitters, must be made energy-autonomous.

“Energy can be harvested from light, vibrations, radio waves, or any number of other things. However, sources like these provide energy unevenly, and they therefore require an energy storage component. In my research, I have developed a component fit for this purpose: a printed supercapacitor,” says TUT Doctoral Student Suvi Lehtimäki.

A supercapacitor is a mix between a battery and a regular capacitor. It cannot store as much energy as a battery, but it can produce higher power spikes and does not lose its capacity as quickly.

“A supercapacitor can be made out of cheap and safe materials, such as plastic film, graphite, activated carbon, paper, and saline water. The salt in the water can be sodium chloride, which is regular table salt. The component is therefore completely safe to keep near foodstuffs or other sensitive materials,” Lehtimäki says.

Supercapacitors can be produced by printing, which reduces production costs.

“Supercapacitors printed on plastic film are also very flexible. This allows them to be placed in a multitude of places, even in clothing as wearable electronics. The best printing method for supercapacitors is screen printing, since it produces thick layers.”

In her thesis, Lehtimäki analysed materials from carbon nanotubes to conductive polymers for their usability in supercapacitors. Activated carbon, the traditional material for electrodes, is currently producing the best results, but new materials are developing fast.

Public defence of a doctoral dissertation on Friday, 7 April 2017

MSc Suvi Lehtimäki’s doctoral dissertation in the field of electronics, entitled “Printed Supercapacitors for Energy Harvesting Applications”, will be publicly examined at the Faculty of Computing and Electrical Engineering of Tampere University of Technology (TUT) in auditorium RG202 in the Rakennustalo building (Korkeakoulunkatu 3, Tampere) at 12:00 on Friday, 7 April 2017. The opponent will be Professor Leif Nyholm (Uppsala University, Sweden). Professor Donald Lupo from the Laboratory of Electronics and Communications Engineering (TUT) will act as Chairman.

Suvi Lehtimäki comes from Jämsä. She is currently working in the Laboratory for Future Electronics research group.

The dissertation is available online at

Further information: Suvi Lehtimäki, tel. +358 40 825 8954,

News submitted by: Riku Haapaniemi
Keywords: science and research, electronics and communications engineering, energy