Design and fabrication of high performance energy storage devices for wearable sensor systems
- 주제(키워드) supercapacitor , wearable devices , sensor devices , nano materials
- 발행기관 고려대학교 대학원
- 지도교수 하정숙
- 발행년도 2016
- 학위수여년월 2016. 8
- 학위구분 박사
- 학과 대학원 화공생명공학과
- 원문페이지 169 p
- 실제URI http://www.dcollection.net/handler/korea/000000068114
- 본문언어 영어
- 제출원본 000045881674
초록/요약
On account of increasing social interest about remote monitoring of health and the environment, many studies on wearable and body-attachable sensing devices have been conducted. In order to monitor health and environmental conditions while devices are attached onto a human body, a few requirements should be satisfied. First, stretchable, flexible, high-performance energy storage devices should be integrated on a wearable system. Second, the energy storage devices should operate health/environmental sensors stably, and be repeatedly charged by an external power source. Third, the sensor device should exhibit high sensitivity and reliability to detect biosignals and environmental signals using power from the connected energy storage devices. Fourth, there should be a way to wirelessly transmit power from an external source to the integrated energy storage device or generate power internally. Last and most importantly, the stable performance of the entire integrated system under deformation due to body movement should be guaranteed. The development of stretchable multi-sensors with interconnected energy storage devices on a single deformable substrate will be essential for the realization of body-attachable health/environmental monitoring devices. To satisfy these requirements of wearable and body-attachable system, my study consists of following themes; stretchable micro supercapacitor, high-performance micro supercapacitor using pseudo-capacitive material, air-stable micro supercapacitor using patternable electrolyte, and body-attachable and stretchable multi-sensors integrated with wirelessly rechargeable energy storage devices. This thesis reports on a stretchable micro-supercapacitor array with planar SWCNT electrodes and an ionic liquid-based triblock-copolymer electrolyte. The mechanical stability of the entire supercapacitor array upon stretching was obtained by adopting strategic design concepts. First concept was the narrow and long serpentine metallic interconnections which were encapsulated with polyimide thin film to ensure that they were within the mechanical neutral plane. Second design concept was an array of 2-dimensional planar micro-supercapacitor with SWCNT electrodes and an ion-gel type electrolyte which was made to achieve all-solid-state energy storage devices. Such formed micro-supercapacitor array showed excellent performance, stable without any noticeable degradation when over-stretched up to 30%. This thesis also reports on the on-chip fabrication of high-performance, flexible micro-supercapacitor (MSC) arrays with hybrid electrodes of multi-walled carbon nanotube (MWNT) /V2O5 nanowire (NW) composites and solid electrolyte, which can power the SnO2 NW UV sensor, also integrated on the same flexible substrate. The patterned MSC using hybrid electrodes of MWNT/V2O5 NW composite with 10 vol% of V2O5 NW exhibited excellent electrochemical performance with a high volume capacitance of 80 F/cm3 at a scan rate of 10 mV/s in PVA-LiCl electrolyte, and good cycle performance maintaining 82% of capacitance after 10,000 cycles at a current density of 11.6 A/cm3. The patterned MSC also showed excellent energy density of 6.8 mWh/cm3 comparable to that of Li-thin film battery (1~10 mWh/cm3), and power density of 80.8W/cm3 comparable to that of state-of-the-art MSCs. In addition, the flexible MSC array on a PET substrate showed mechanical stability when bending with bending radius down to 1.5 mm under both compressive and tensile stress. Even after 1,000 bending cycles at a bending radius of 7 mm, 94% of the initial capacitance was maintained. Furthermore, I showed the operation of a SnO2 NW UV sensor run by such fabricated MSC array integrated in the same circuit on the PET substrate. Next, this thesis describes the fabrication of air-stable, high-performance, planar microsupercapacitors (MSCs) on a flexible poly(ethylene terephthalate) substrate with spray-coated Multi-Walled Carbon Nanotubes(MWCNT) electrodes and patterned ionogel electrolyte, i.e., poly(ethylene glycol) diacrylate/1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. The flexible MSC showed good cyclability, retaining ~80% of its initial capacitance after 30,000 cycles, and exhibited good mechanical stability maintaining 95% of its initial capacitance after 1,000 bending cycle with bending diameter of 3 mm under compressive stress. The MSC had high electrochemical stability retaining 90% of its initial capacitance when exposed to air for 8 weeks. Furthermore, vertical stacking of MSCs with patterned solid film of ionogel electrolyte could increase the areal capacitance dramatically. This flexible MSC has potential applications as an energy-storage device in micro/nano-electronics without any need for encapsulation for air stability. Finally, this thesis reports on the successful fabrication of bio-environmental sensors integrated with a wireless Radio Frequency (RF) power receiver and an array of microsupercapacitors (MSCs) connected through embedded liquid metal interconnections on a single stretchable substrate. Sensors are operated by an array of MSCs which is repeatedly charged by the wireless RF power receiver. A fragmentized graphene foam sensor detects the neck pulse, voice, saliva swallowing, and body movement while the entire system is attached to skin. Both hazardous NO2 gas and UV are stably detected by a MWNT/SnO2 nanowire sensor even under uniaxial stretching up to 50%. This study demonstrates, for the first time, great potential of my integrated multi-sensor system in practical applications for body-attachable, wireless, wearable devices.
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Contents
Abstract i
Contents v
List of Figures vii
List of Table xvii
1. Introduction 1
1.1 Experiment background 6
1.1.1 Supercapacitor 6
1.1.2 Stretchable interconnections 9
1.1.3 Nanomaterials based sensor devices 11
1.2 Experimental 13
1.2.1 Preparation of carboxylic acid functionalized SWCNT solution for
spray coating 13
1.2.2 Fabrication of all-solid-state stretchable supercapacitor array 13
1.2.3 Characterization of all-solid-state stretchable supercapacitor 19
1.2.4 Synthesis of MWNT / V2O5 NW Composites 19
1.2.5 Fabrication of the all-solid-state micro-supercapacitor array 19
1.2.6 Synthesis of PEGDA/[EMIM][TFSI] and PVA/H3PO4
electrolytes 24
1.2.7 Fabrication of MSC with patterned ionogel 24
1.2.8 Fabrication of wireless power receiver 25
1.2.9 Fabrication and characterization of MWNT/SnO2 nanowire hybrid film
sensor 25
1.2.10 Fabrication of stretchable substrate and integration of devices 28
1.2.11 Characterization of integrated system 29
1.3 Thesis overview 30
1.3.1 Fabrication of stretchable solid-state micro-supercapacitor array 30
1.3.2 High performance flexible micro-supercapacitor arrays:
Electrode 32
1.3.3 High performance flexible micro-supercapacitor arrays:
Electrolyte 34
1.2.4 Body-attachable and stretchable multisensors integrated
with wirelessly rechargeable energy storage devices 36
2. Chapter 2. Fabrication of stretchable solid-state micro-
supercapacitor array 38
3. Chapter 3. High performance flexible micro-supercapacitor
arrays: Electrode 56
4. Chapter 4. High performance flexible micro-supercapacitor
arrays: Electroyte 81
5. Chapter 5. Body-attachable and stretchable multisensors integrated
with wirelessly rechargeable energy storage devices 105
6. Chapter 6. Conclusion 136
7. Chapter 7. Future work 140
References 142
