Eco-Friendly Food Packaging Doubles as Quality Sensor

Scientists at the Institute of Advanced Study in Science and Technology (IASST), led by Prof Devasish Chowdhury of the physical sciences division and his student Sazzadur Rahman, an INSPIRE senior research fellow, have developed a smart biodegradable biopolymer nanocomposite that can detect relative humidity — an invention that is useful in food packaging.

Two biopolymers, guar gum (a variety of beans) and alginate (obtained from brown algae), were blended with carbon dots (nanomaterial) to make a nanocomposite film that was successfully used to detect relative humidity. The smart sensor is based on the fluorescence ‘on-off’ mechanisms against humidity.

The food industry has an increasing need for non-toxic, biodegradable, low-cost, and environment-friendly packaging material to replace petroleum-based material like plastics. Besides, it needs smart and active packaging material to detect and report food quality in real time. Such smart and active packaging systems respond to signals while interacting with the food packaging environment. Perishable packed foods are easily damaged by changes in relative humidity.

The nanocomposite film shows a change in fluorescence in the presence of high humidity. Hence, the fabricated nanocomposite film can monitor the packed food’s freshness using just a UV light source. “Smart and active packaging can help consumers select a fresh product without breaking the pack. Such innovative packaging boosts sales and reduces consumers’ time in identifying fresh food products,” said Chowdhury.

Polyaniline-powered supercapacitors

Supercapacitors or ultracapacitors are energy storage devices; they combine the characteristics of conventional capacitors and batteries to give a sudden kick-start to devices by providing a large amount of power and sustained energy release. A new low-cost, pristine, conducting polymer-based electrode and redox-active electrolyte combination can give enhanced electrochemical performance and cycling stability to supercapacitors, facilitating energy storage and powering in wearable integrated devices.

The electrode materials play a vital role in determining the performance and stability of supercapacitors. Conducting polymers like polyaniline and polypyrrole are excellent candidates for electrode materials due to their flexibility, stability and tunable electrical and electrochemical properties. They are also inexpensive, lightweight and can be synthesised easily. However, supercapacitors fabricated with these electrodes fail to sustain their electrochemical capacitance (ability to store electric charge) after a few cycles of continuous operation. The poor energy density of these devices is another issue that limits their usefulness.

The Materials for Energy Storage and Optoelectronic Devices Group, headed by Dr Sreekanth J Varma of the physics department of Sanatana Dharma College, Alappuzha, has found a means to improve the performance of polyaniline-based supercapacitors and achieve high specific capacitance per unit area, or areal capacitance, and prolonged life. They found that when electrodes made from pristine, porous, conducting and high molecular-weight polyaniline, synthesised through self-stabilised polymerisation (SSDP), are used with an electrolyte powered by a redox-additive (which boosts redox reactions), the energy storage devices deliver incredible performance.

The conducting polymer-based electrode is lightweight and highly stable. The supercapacitors’ enhanced performance and long life are attributed to the binder-free nature, porosity, high and homogeneous molecular weight, and appreciable conductivity of the electrode material, as also the electrode and redox-activated electrolyte combination.

Germ-killer concoction

Over time, air filters become a part of the problem they are supposed to solve, by becoming breeding grounds for microbes. Dr Suryasarthi Bose, associate professor in the department of materials engineering at Indian Institute of Science, Bengaluru, has come up with a concoction that kills the germs in filters.

The plant-based biopolymer, when coated on filters, leads to the formation of hydrogen peroxide, which ruptures the germs. The ability of the coated filters to deactivate germs has been successfully validated at government labs like NABL and they are in use at several hospitals and other organisations in India.

AiRTH, a start-up that was involved in the development of the product, has taken up the manufacture of this biopolymer. “The germ-destroying filters will decrease the burden on the healthcare system, and (help) re-open commercial spaces like offices with confidence and have a safe working environment,” says Ravi Kaushik, CEO, AiRTH.

Therapeutic protein and milk

Therapeutic proteins (TP) have a great role in counteracting diseases like diabetes, arthritis, blood clotting, and several others. However, the exorbitant cost of producing TPs has placed them beyond the reach of the common masses. Insulin, alpha and gamma interferons, blood coagulation factors, and so on, are some of the most important marketable products. Milk-based expression of these therapeutics in livestock animals has the potential to make them affordable.

The National Institute of Animal Biotechnology, Hyderabad, has used mice and rabbits to develop a technology for generating these costly therapeutic proteins in milk. This would reduce the need to import such therapeutics, according to NIAB.

Anti-corrosion coating

Scientists at the International Advanced Research Centre for Powder Metallurgy & New Materials (ARCI), Hyderabad, have developed low-cost iron-based intermetallic powders that can be used as a corrosion-resistant coating for materials exposed to harsher environments like high temperature in thermal power plants, where oxidation, corrosion, and wear-and-tear take place simultaneously.

There is a need to protect the component surface from wear-and-tear using a suitable material for enhanced economic viability.

Such surface coating on a turbine blade can enhance the service life and hence increase the operation hours of the turbine. ARCI scientists have addressed wear-and-tear by synthesising iron-based intermetallic powders and depositing them on the surface using the detonation spray coating (DSC) technique.

Additionally, ARCI has developed gas-atomised iron aluminide powder and used DSC to deposit it on mild steel substrates without any cracks or spalling. The coatings have demonstrated four times increased corrosion resistance in aqueous corrosive media than mild steel.



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