PDMS의 기계적 특성 최적화를 통한 트랜스퍼 프린팅 기반의 다기능 웨어러블 디바이스 개발 = Microfabrication for Wearable Devices Based on Transfer Printing using optimzation of PDMS Mechanical Property

국문 초록 (Abstract)

본 연구는 PDMS의 기계적 특성을 이용해 트랜스퍼 프린팅 기반의 유연한 웨어러블
디바이스를 제작하는 두 가지의 공정에 대해서 제안한다. 먼저 제안된 공정은 기존의
트랜스퍼 프린팅 기술은 스탬프 제작, 표면처리 기술, 분리속도 조절 등 복잡한 제어가
필요하여 공정 시간이 길어지고 비용이 비싸다는 단점을 PDMS의 접착력 조절을 이용
해 해결하고자 한다. 이는 PDMS의 접착력과 유연성을 조절할 수 있는 PEIE을 사용함
으로써 특수한 장비나 정밀한 제어가 필요가 없는 저비용으로 간단하고 빠른 트랜스
퍼 프린팅 기반의 미세공정을 제안한다. 하지만 여전히 PDMS 기판과 금속 층 사이의
모듈러스 차이 때문에 발생하는 기계적 불일치가 문제가 된다. 이러한 문제를 해결하
기 위해서 두 번째 제안된 공정인 사전변형(prestrained)된 기판에 금박을 전사를 한
후 기판에 가해진 인장을 풀어, 3차원적으로 물결 형태를 가지는 금박 패턴을 만드는
공정을 제안한다. 또한 두 번째 제안된 공정은 센서마다 필요한 전기기계적 특성이 다
른데 이를 최적화하고자 다양한 범위에서의 prestrain 비율을 이용해 최종적으로 여러
번 전사하는 멀티 스탬핑 전사 공정을 제안한다. 이 두 가지 미세 가공 공정의 유효성
을 다기능 피부부착형 센서 패치 제작을 통해 실효성을 입증했다

다국어 초록 (Multilingual Abstract)

Recent advancements in microfabrication process for wearable device have
enabled untethered continuous health monitoring. While various flexible
materials such as polydimethylsioxane (PDMS) has been utilized for flexible
and stretchable materials for wearable sensors, conventional microfabrication
processes have required specialized MEMS facility and equipment. Here, we
demonstrate a simple and low-cost transfer-printing microfabrication process
that employs polyethyleneimine ethoxylated (PEIE) to control the adhesion
properties of the donor/receiver PDMS layers.
But, the fabrication of wearable device transferred on PDMS substrate has
limitations including need for inadequate stretchability of PDMS. Moreover, the
use of metal layers on a soft PDMS substrate can lead to mismatch in
mechanical modulus. Here, we proposed a process of prestrained substrate to
address mismatch problems. Furthermore, we introduce a multi-stamping
transfer printing using prestrained substrate. We characterized the
electromechanical properties of the transferred gold patterns and
demonstrated its performance as the wearable temperature, EMG and strain
sensors.

목차 (Table of Contents)

• 그림 차례 ········································································································································ ⅲ
• 요약 ·················································································································································· ⅴ
• I. 서론 ··············································································································································· 1
• 1. 연구 배경 ·································································································································· 1
• 2. 선행 연구 ·································································································································· 3
• 3. 본 연구의 배경 ························································································································ 7
• 4. 본 연구의 목적 ······················································································································ 10
• II. 연구 방법 ·································································································································· 13
• 1. PDMS의 접착력 조절을 이용한 전사 인쇄 기술 ···························································· 14
• 2. Prestrain된 PDMS 기반의 다중 스탬핑 기술 ································································ 22
• III. 연구 결과 : PDMS의 접착력 조절을 이용한 전사 인쇄 공정 ···································· 27
• 1. 전사 공정을 위해 제조된 sPDMS의 특성 ······································································ 27
• 2. 전사 메커니즘 ······················································································································ 29
• 3. 전사된 금 패턴의 특성화 결과 ··························································································· 30
• 4. 임계값에 따른 Filling factor ····························································································· 32
• 5. Encapsulation 된 샘플 침투 실험 결과 ········································································· 33
• 6. sPDMS의 편의성 ··················································································································· 35
• 7. 다기능 센서 패치 ·················································································································· 36
• 8. Stretch test 및 스트레인 센서 성능 검증 ······································································ 37
• 9. EMG 센서 성능 검증 ············································································································ 39
• IV. 연구 결과 : Prestrain된 sPDMS 기반의 다중 스탬핑 공정
• 1. Prestrain된 sPDMS 기판으로 인한 금 패턴의 변형 메커니즘 ································· 40
• 2. Prestrain된 sPDMS 기판에 전사된 금 도선의 전기적 특징 ···································· 42
• 3. 다중 스탬핑 전사 공정 최적화 ··························································································· 44
• 4. Prestrain된 기판 위에 제작된 다기능 센서 패치 ······················································· 46
• 5. Prestrain에 따른 호환성이 있는 금 패턴 디자인 최적화 ············································ 47
• 6. 스트레인 센서, EMG 센서 및 온도 센서 검증 ······························································· 49
• V. 고찰 및 후속 연구 ·················································································································· 51
• VI. 결론 ·········································································································································· 53
• 참고문헌 ········································································································································· 54
• Abstract ········································································································································ 57