Energy harvesting, the process by which energy is derived from external sources, captured and stored, is a key area of research today. Wearable electronics and small wireless autonomous devices have been made possible, but efficiency and scalability have always presented a challenge. Piezoelectric energy is not new, but now a team of researchers has developed a new type of electricity-harvesting rubber sheet that is durable, versatile and opens up new applications to power electronic devices.
A team from Princeton University and the California Institute of Technology has developed a material composed of ceramic nanoribbons embedded onto silicone rubber sheets. The novel material generates electricity when flexed and is highly efficient at converting mechanical energy to electrical energy. In fact, the opposite is true as well: the material flexes when electrical current is applied to it. This development allows integration of highly efficient energy conversion materials onto stretchable, biocompatible rubbers, making breakthroughs in implantable or wearable energy harvesting systems possible. The research was published in Nano Letters, a journal of the American Chemical Society under the title ‘Piezoelectric ribbons printed onto rubber for flexible energy conversion.’
The team is the first to successfully combine nanoribbons of lead zirconate titanate (PZT) – a ceramic material that is piezoelectric – and silicone. PZT generates an electrical voltage when pressure is applied to it, and is the most efficient among such materials, being able to convert 80% of the mechanical energy applied to it into electrical energy. This makes it 100 times more efficient than quartz. The team first fabricated PZT nanoribbons and then, in a subsequent process, embedded the ribbons into clear sheets of silicone rubber, thus creating ‘piezo-rubber chips.’ Since silicone is biocompatible, this new material can be implanted in the body to perpetually power medical devices, without the challenge of the body rejecting them.
The material is scalable as well. The team believes that once better expertise at making these chips is achieved, larger and larger sheets of them can be used to harvest more energy. Due to their electromechanical coupling, piezoelectric crystals are part of smart materials that can function as sensors/actuators, bioMEMS devices and energy converters. Natural body movements such as breathing and walking could soon power pacemakers and mobile phones. This new material can open the door to other kinds of applications, such as use for microsurgical devices, thanks to its ability to flex when an electrical current is applied.
For more information contact Patrick Cairns, Frost & Sullivan, +27 (0)18 464 2402, patrick.cairns@frost.com, www.frost.com
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