Spongy Ag Foam for Soft and Stretchable Strain Gauges

• Published in: ACS applied materials & interfaces 2024-05, Vol.16 (20), p.26613-26623
• Main Authors: Hong, Seokkyoon, Zhang, Haozhe, Lee, Junsang, Yu, Tianhao, Cho, Seungse, Park, Taewoong, Walsh, Julia, Ji, Yuhyun, Kim, Joshua Jeremiah, Lee, Hyowon, Kim, Dong Rip, Xu, Baoxing, Lee, Chi Hwan
• Format: Article
• Language: English
• Subjects: Functional Nanostructured Materials (including low-D carbon)
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.4c04719

Strain gauges, particularly for wearable sensing applications, require a high degree of stretchability, softness, sensitivity, selectivity, and linearity. They must also steer clear of challenges such as mechanical and electrical hysteresis, overshoot behavior, and slow response/recovery times. However, current strain gauges face challenges in satisfying all of these requirements at once due to the inevitable trade-offs between these properties. Here, we present an innovative method for creating strain gauges from spongy Ag foam through a steam-etching process. This method simplifies the traditional, more complex, and costly manufacturing techniques, presenting an eco-friendly alternative. Uniquely, the strain gauges crafted from this method achieve an unparalleled gauge factor greater than 8 × 103 at strains exceeding 100%, successfully meeting all required attributes without notable trade-offs. Our work includes systematic investigations that reveal the intricate structure–property–performance relationship of the spongy Ag foam with practical demonstrations in areas such as human motion monitoring and human–robot interaction. These breakthroughs pave the way for highly sensitive and selective strain gauges, showing immediate applicability across a wide range of wearable sensing applications.