STUDY ON THE POTENTIAL OF BELITUNG TARO STARCH (XANTHOSOMA SAGITTIFOLIUM)-BASED HYDROGELS FOR FLEXIBLE SENSOR APPLICATIONS

• Main Author: Nafisah, Nur'aini
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/82891
• Institution: Institut Teknologi Bandung

The ease of application of flexible sensors on various surfaces has led to their widespread development. Hydrogel, a polymer crosslinked material with a three- dimensional structure, shows outstanding potential as a flexible sensor due to its solid-like mechanical characteristics and liquid-like transport characteristics. However, the development of hydrogels from natural materials, such as starch- based taro Belitung hydrogels, aims to reduce the growing electronic waste. Taro belitung, or Xanthosoma sagittifolium, is an easy plant to grow in various regions of Indonesia, so it is a renewable natural material. This study synthesized taro starch-based hydrogels by examining the impact of CaCl2 inorganic salt as a conductive ion contributor and glycerol as a plasticizer, using the freeze-thaw method, on physicochemical and electrical properties. Taro starch-glycerol-CaCl2 (TSGC) hydrogel has a flexible and transparent shape, in contrast to taro starch (TS) and taro starch-glycerol (TSG) hydrogels, which are white and more rigid. A transparent display will make it easier for the sensor to identify the detected surface. The SEM image shows the structural changes within the hydrogel between TS, TSG, and TSGC. The addition of glycerol and CaCl2 salt increased the hydrogel's density and reduced its porous size due to the cross-linking of Ca2+ ions with starch chains. After adding glycerol and CaCl2, the degree of swelling decreased. This is a positive outcome when used as a flexible sensor to prevent rapid swelling. The amount of weight loss also increased with the addition of glycerol and the increase in CaCl2 concentration. FTIR analysis confirmed the functional groups of taro starch and glycerol in the TSGC hydrogel. The XRD pattern showed that CaCl2 removed the crystallinity of starch, resulting in an amorphous hydrogel. The mechanical tests, including the compressive and tensile tests, revealed that glycerol and CaCl2 enhanced the flexibility of the TSGC hydrogel. It had an elastic modulus of 0.35 kPa and could stretch up to 120% before breaking. Furthermore, in adhesive tests, the addition of CaCl2 also influences the hydrogel's adhesive characteristics, allowing it to adhere to different materials without requiring additional external adhesives. As for its electrical properties, this hydrogel has a conductivity of about 5 mS/m and can respond to strain changes with a gauge factor (GF) of 0.076. In addition, hydrogel can be applied to the skin surface to monitor changes in human motion. Cell cytotoxicity tests also revealed that the hydrogel has good biocompatibility, with cell viability reaching 92%. The physicochemical, electrical, and biocompatibility properties of Belitung taro starch hydrogel (TSGC) indicate its potential for use as a flexible sensor.