Wearable gold decorated direct laser writing graphene for ultra-minor strains

Abstract

This paper reports a flexible and wearable piezoresistive strain sensor composed of the LIG/PDMS nanocomposite. LIG was first prepared on commercial Kapton tape by CO₂ laser scanning. The presence of carbon atoms and their high ratio compared to oxygen atoms were confirmed using XPS, XRD, and Raman tests. FESEM images also showed the presence of multilayer graphene sheets in a porous foam. The strain sensor was fabricated by transferring LIG to a PDMS elastic polymer substrate. This sensor exhibits high sensitivity (GF_max. = 78.2), low hysteresis, and a wide working range (strains of 1–100%). It also has a stable and fast dynamic response and provides good reversibility and repeatability. After 10 000 cycles, the signal peak changed only 2%, indicating its long-term durability and stability. The Au-enhanced sensor exhibits more regular response patterns and higher sensitivity (GF_max. = 220.3). It showed a very low detection limit of 0.1%. In addition to positive SNR numbers at 0.1% strain, a high gauge factor of 45.8 was obtained, which is very high compared to that of most reported strain sensors and shows Au/LIG/PDMS sensor's great sensitivity at deficient strains. Gold deposition was performed in two ways (gold deposition on PI film and gold deposition on LIG). Au/LIG-based sensors, with their unique characteristics, are well-suited for detecting subtle strains like those found in arterial pulses and blood pressure. This makes them strong contenders for tactile and wearable sensor applications. This LIG-based sensor holds great promise for the future development of wearable technology, such as flexible sensors integrated into clothing or even artificial skin.