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[주간세미나] 2015년 11월 16일
관리자 2015-11-04

<김상우교수 Lab.>

* 발표자 : 유한준

* 제목 : Thermally Induced Strain-Coupled Highly Stretchable and Sensitive Pyroelectric Nanogenerators

* 내용 : Converting wasted energy into electrical energy has received great attention and become an important research field, especially since the commercialization of wearable device systems, wireless sensors and small electronics with low power consumption. Harvesting energy from wasted thermal energy in our environment would be a great opportunity and very important for low power consumption electronics. There is still a lack of research on energy harvesting based on the pyroelectric effect. In addition, the reported power-generating performance of pyroelectric nanogenerators (PNGs) is relatively low compared with other energy harvesters. Therefore, enhancement of the pyroelectric performance is one of the significant technical issues for meaningful usage of pyroelectric NGs as a new energy harvesting device. We innovatively designed a stretchable PNG (SPNG) based on a coupling of piezoelectric and pyroelectric effects using micro-patterned P(VDF-TrFE) and micro-patterned polydimethyl-siloxane (PDMS). We utilized the different thermal expansion characteristics of two materials to build strain on ferroelectric P(VDF-TrFE) films to generate a piezoelectric effect using only thermal energy. We compared the SPNG with a normal PNG (NPNG) which is based on the flat P(VDF-TrFE) coated onto a flat and rigid Ni/SiO2/Si substrate, and we found that the highly sensitive SPNG operates from temperature changes that range from extremely low (&8710T &8776 0.64 K) to high (&8710T &8776 18.5 K), and generates maximum around 2.5 V of output voltage and 570 nA/cm2 of output current density. Thermally induced stress, strain, and piezoelectric potential in the P(VDF-TrFE) of the SPNG and the NPNG were simulated in order to support the experimental results using COMSOL multi-physics simulation software. We successfully drove small electronic devices, such as a liquid-crystal display, light-emitting diodes, using output power from a SPNG. The results obtained in this work strongly suggest that the SPNG could be applied in various kinds of promising device applications such as self-powered wireless sensors, highly sensitive temperature imaging, and self-powered biomedical applications.

* 발표자 : 이정환

* 제목 : Shape memory polymer-based self-healing triboelectric nanogenerator

* 내용 : Recently, triboelectric nanogenerators (TENGs) have received increasing interest due to their large potential for mechanical energy harvesting. Important progress has been achieved in increasing the output power and efficiency while new structures have emerged. In particular, their robustness and endurance have increased, but some critical concerns still remain about the degradation and lifetime of TENGs. How will TENGs age under intensive use in our daily lives? To address this issue, we propose in this paper to use shape memory polymers (SMPs) to extend TENGs’ lifetimes and guarantee their performance. For this purpose we introduce a new smart SMP-based self-healing TENG which has the capacity to be healed and to recover good performance after degradation of its triboelectric layer. We studied the degradation and healing process of the SMP&8211TENG, and the improvement in its endurance and lifetime, and thus demonstrate the huge potential of self-healing SMP&8211TENGs.
[주간세미나] 2015년 11월 9일
[주간세미나] 2015년 11월 23일