Small-film-type ion sensors are garnering considerable interest in the fields of wearable healthcare and home-based monitoring systems. The performance of these sensors primarily relies on electrode capacitance, often employing nanocomposite materials composed of nano- and sub-micrometer particles. Traditional techniques for enhancing capacitance involve the creation of nanoparticles on film electrodes, which require cost-intensive and complex chemical synthesis processes, followed by additional coating optimization. In this study, we introduce a simple one-step electrochemical method for fabricating gold nanoparticles on a carbon nanotube (Au NP–CNT) electrode surface through cyclic voltammetry deposition. Furthermore, we assess the improvement in capacitance by distinguishing between the electrical double-layer capacitance and diffusion-controlled capacitance, thereby clarifying the principles underpinning the material design. The Au NP–CNT electrode maintains its stability and sensitivity for up to 50 d, signifying its potential for advanced ion sensing. Additionally, integration with a mobile wireless data system highlights the versatility of the sensor for health applications.

1. Introduction
2. Experimental
    2.1 이온 선택성 전극(ISE) 제작 및 구조 분석
    2.2 커패시턴스 측정
    2.3 이온 센서 특성 평가
    2.4 기준전극 형성
    2.5 회로와 통합된 센서 제작
3. Results and Discussion
    3.1 Au NPs-CNT 구조 분석 결과
    3.2 커패시턴스 분석 결과
    3.3 이온 센서 성능 평가 결과
    3.4 회로와 통합한 센서 특성 평가
4. Conclusion
Acknowledgement

• 김도연(부경대학교 재료공학과) | Do Youn Kim (Major of Materials Engineering, Pukyong National University, Busan 48513, Republic of Korea)
• 손한별(부경대학교 재료공학과) | Hanbyeol Son (Major of Materials Engineering, Pukyong National University, Busan 48513, Republic of Korea)
• 임효령(부경대학교 휴먼바이오융합전공) | Hyo-Ryoung Lim (Major of Human Biocovergence, Pukyong National University, Busan 48513, Republic of Korea) Corresponding Author