Sensor films are finding wide range of applications. Different type of sensing films is fabricated for the identification of chemicals, ions, heavy metals, changes in the pH, etc. The present report is on the fabrication of pH sensitive films from completely natural sources-soy protein isolate, chitin nano whiskers and flower extract. The highly crystalline chitin nano whiskers (CNW) were extracted from prawn shell under neutral condition via steam explosion technique. Multifunctional Soy protein isolate (SPI) films were prepared by adding chitin nanowhisker and Clitoria ternatea flower extract and its effect on thermal, mechanical and moisture properties of SPI film was investigated. The isolated CNW presented a needle like morphology with a diameter of 10–50 nm and a crystallinity index of 99.67%. The extracted chitin nanowhisker was used to prepare biodegradable films with soy protein isolate immobilized with anthocyanin from Clitoria ternatea flower extract. The prepared Soy protein -chitin nanowhisker films was found to have a tensile strength of about 15.45 ± 0.97 MPa with 8% chitin nanowhisker addition. The addition of CTE was found to decrease the tensile strength of SPI-CNW film but was found to make the film pH sensitive. The developed indicator film showed visible color changes in acidic and basic medium and hence can be used to monitor the freshness of food materials.

Smart materials are much discussed in the current research scenario. The shape memory effect is one of the most fascinating occurrences in smart materials, both in terms of the phenomenon and its applications. Many metal alloys and polymers exhibit the shape memory effect (SME). Shape memory properties of elastomers, such as rubbers, polyurethanes, and other elastomers, are discussed in depth in this paper. The theory, factors impacting, and key uses of SME elastomers are all covered in this article. SME has been observed in a variety of elastomers and composites. Shape fixity and recovery rate are normally analysed through thermomechanical cycle studies to understand the effectiveness of SMEs. Polymer properties such as chain length, and the inclusion of fillers, such as clays, nanoparticles, and second phase polymers, will have a direct influence on the shape memory effect. The article discusses these aspects in a simple and concise manner.

The pH-sensitive intelligent film is a much-awaited development in the field of packaging as it informs the consumers about the quality of the prepacked food by its visually detectable color changes. In this study, the indicator films (AP-SPI-RCE) were produced using whole arrowroot powder (AP), soy protein isolate (SPI), and food-grade red cabbage anthocyanin (RCE). Two different concentrations of RCE (5% and 7% (based on AP)) were added to AP-SPI matrices to form AP-SPI-RCE₅ and AP-SPI-RCE₇ films. The AP-SPI-RCE₅ film showed the highest tensile strength, thermal stability, 16% decrease in moisture content, and 41% decrease in solubility. Films incorporated with anthocyanin showed distinguishable color changes in different pH buffers and good sensitivity for ammonia vapor detection. The indicator film displayed visual color changes corresponding to pH and total volatile basic nitrogen (TVB-N) changes when the shrimp sample was spoiled. Hence, this food-grade anthocyanin incorporated film can act as a smart material to detect spoilage of fresh shrimp and meat which produce ammonia on spoilage. In addition, these strips are suggested to be utilized in the monitoring of the ammonia concentration in fish farming ponds.