Kazuaki Yazawa
Research Associate Professor-Birck Nanotechnology Center
Purdue University
TT: Of what material is the fabric designed by you to harness human body heat to provide energy made up? Why did you choose that particular material?
There are four materials in the component level: two exterior layers of polymer, metal electrodes, fibre core (e.g. glass fibre), and semiconductor to cover the core fibre.
Item number one is necessary to conduct the heat from skin to the contacts of the fibres; item two is used to harvest electricity out of the semiconductor; item three is necessary to mechanically support the flexible woven structure of fabric; and item four is the essential of heat-to-electric energy conversion.
TT: What inspired you to venture into this area? How long have you been working on this project?
I have been thinking of body heat recovery since the mid-1990s. Over a recent decade of academic research, I developed a generic method to harvest maximum heat energy with thermoelectrics. Woven fabrics were discovered to fill a need for a flexible energy conversion device.
TT: How do you design clothing with this fabric for various uses? In what form do you see this clothing: full dresses, gowns or only undergarments?
This technology is still in an early stage of development. There will be a variety of future research to explore many types of fabrics and applications for fashion. At this point, a first step may be in sporting/athletic gear-to-wear or medical/health equipment. As the technology matures, there would be many opportunities to integrate with fashion and other areas.
TT: How will it function, for example, for medical purposes as in heart monitoring? Will it be embedded in the clothing? And how will the heat generated by the patient's gown get transferred to the device? Will there be direct monitoring of heart data by a physician?
With proper electrical sensors and wireless transmitters available in market, there is a lot of potential to develop products for monitoring the status or activities of the human body. IoT technology may enable us to do more than medical/health care. A doctor, who is evaluating your heat beat, blood pressure, perspiration, respiration, and/or dynamic motion, can be thousands of miles away, or even on a airplane. These sensors/electronics are typically very small and printable and easily placed in the energy harvesting tape/band/patch/fabric.
A stationary human generates a hundred watts of heat energy, and with the activity of sports/exercise even more heat is generated. Our proprietary heat transfer techniques are used to capture energy from the temperature difference between the skin surface and the ambient air temperature. Our future research will improve the energy capture and utility of the device.
TT: What will be the benefit to a patient/user in comparison to the current situation?
With a thermoelectric technology, there is no need to carry bulky, heavy batteries, or charge your device.
TT: There have been reports of risk to patients who use wireless devices such as heart monitor if somebody hacks the software. How safe will the concept proposed by you be?
The woven thermoelectric generator is a passive device, meaning that it - by itself - is a non-communicating, unhackable system. It is possible that any device, a woven thermoelectric device is connected to, could be prone to interference by electromagnetic fields but not the thermoelectric power system itself. Preventing unintended interference is critically important, especially for medical devices. We will work with any medical device partners to assure that all standards of testing protocol and independent validation are followed.
TT: Have you taken this further? Have you signed any agreement with any company/hospital to test this technology in medical or any other application?
We have begun to discuss continued research with interested partners but have yet to formalise any final agreements.
TT: Since the process involves generation of electricity, is there any risk to the user?
There is no risk to a user at the level of electricity generated. The power output of a thermoelectric generator would be in the range of one or two coin/button battery(ies) common in wrist watches. There is no harm to touch well-sealed coin batteries, and there is even less risk from this generator. Furthermore, the device is electrically insulated by exterior polymer; so the surface of the skin will never touch any electricity, and unlike a battery it will never run out.
TT: How do you use this fabric for athletes? What happens to the power generated by an athlete's garment? How does it help him/her?
Monitoring local activity will help to develop the muscles effectively, which is important for an athlete. Sensing pressure, temperature, sweat, local muscle group pulse, etc, are all possible to monitor with a lightweight, battery-free device.
TT: How do you use this fabric for generating power from a cup of coffee or chimney? And then what do you do with this power?
Do you know a Drink Comfort Grip? I imagine a product that looks somewhat similar. In theory, from 500 millilitres of hot coffee, 5 watts x 6 minutes (500mW) of electricity may be generated. This kind of energy conversion can enable charge of a small electronic device for one time emergency.
TT: Do you see this fabric making a mark in fashion industry?
I hope, yes. The flexible power device could help to bring various electronics into clothing and fabrics and change the fashion quite a bit. Perhaps, your dress in the future may express something by LED, or changing its colour, or interactive displays, etc, to heighten personal expression, as an example.
Published on: 11/05/2017
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