Jelly could soon power our portable devices and IoT devices

Figure 1. Giant thermoelectric energy from ionic thermoelectric materials (i-TE). (A) i-TE gelatin materials-X KCl-meter/ /north FeCN4- / 3- (X is KCl and meter/ /north are the molar concentrations of K4Fe (CN) 6 / K3Fe (CN) 6, respectively) in this work as Gelatin (X = 0 M, meter/ /north = 0 M), Gelatin-FeCN4- / 3- (X = 0 M, meter/ /north = 0.42 / 0.25 M), gelatin-KCl (X = 0.8 M, meter/ /north = 0 M) and Gelatin-KCl-FeCN4- / 3- (X = 0.8 M, meter/ /north = 0.42 / 0.25 M, ratio of volume of water to gelatin rv = 2.0 and 3.0). (B) Absolute thermal power of i-TE materials that contain the thermodiffusion effect or the thermogalvanic effect. Credit: Universidad del Sur de Ciencia y Tecnología.

Innovative research published in Science and led by the University of Science and Technology of the South (SUSTech) discovered that gelatin could be used to power devices in the future, using only the heat generated by the human body.

Associate Professor Weishu Liu (MSE, SUSTech) has led his research team, in collaboration with Professor Gang Chen of the Department of Mechanical Engineering, Massachusetts Institute of Technology (MIT), to develop a portable proof-of-concept device powered by jelly. The article was published online in the high-impact academic journal Science as First Release, under the title “Giant Ionic Gelatin Thermopower Near Room Temperature,” Thursday April 30, 2020.

Most thermoelectric materials are inorganic semiconductors that require noble metals or processing technology. Researchers have focused on exploring new thermoelectric materials near room temperature, which use the Seebeck effect to convert thermal energy into electrical energy. The use of self-powered electronic thermoelectric devices requires the integration of thousands or even tens of thousands of small 10 to 100 micron thermoelectric elements, or the inclusion of a DC-DC voltage amplifier at a cost of output power density.

Prior to the voltage equalization challenge, Weishu Liu called for a “go beyond Seebeck” exploration by considering the use of ions and electrical domain as an energy carrier or other new mechanisms to solve this thermoelectric application challenge. These recommendations were made in his article entitled “New trends, strategies and articles …: a perspective”, published in Materials Today Physics in 2017

Figure 2. Proof of concept of the i-TE portable device. (A) Tensile test of the i-TE material. (B) Voltage generated from a flexible proof-of-concept i-TE portable device with 25 unipolar elements (5 × 5 × 1.8 mm) in series used on the back of the human hand. (C) Power curves (line, -), voltage (dashed line, -), output current (dashed line, – ∙ -) collecting actual body heat. (D) Comparison of performance in output voltage and power of portable device by using e-TE materials and quasi-solid state i-TE materials under real human body use condition. north represented the number of n / p type thermoelectric elements in portable devices. Credit: Universidad del Sur de Ciencia y Tecnología.

The article published today in Science It is a reflection of many years of hard work. The gelatin in question is a high molecular weight substance found in the bones. It is sought after by chefs in a wide range of kitchens, while being an essential raw material for various industrial applications.

The research team originally proposed that a quasi-solid ionic gel could achieve a giant thermoelectric potential effect by combining the effect of diffuse ion entropy and the reaction entropy of the redox couple (chemical reduction-oxidation reaction). They achieved 17.0mV K-1 thermoelectric power in quasi-solid state ionic thermoelectric material, which is almost two orders of magnitude higher than typical electronic thermoelectric

The research team assembled twenty-five units to represent a proof-of-concept device. Each unit was assembled into a flexible portable device, using a human body for energy. The researchers were able to achieve a voltage of up to 2.2 volts (V) and a maximum output power of 5 μW. While that seems small, it can control the sensors of most Internet of Things (IoT) devices.

Weishu Liu said, “The experimental discovery of the giant thermoelectric effect brought us joy, and then many questions. Professor Gang Chen provided us with the essential guidelines for answering each question one by one. It also allowed us to realize the truth about joy. of research: never give up your exploration, because it is your dream. You must keep searching until you get the truth, to find new knowledge. ”

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Southern University of Science and Technology