An everyday sweetener offers a surprisingly powerful engine for transparent, stretchable electronics

Professor Kyungwho Choi's team of the School of Mechanical Engineering at Sungkyunkwan University, in collaboration with Professor Jinsoo Kim's team in the Department of Chemical Engineering at Kyung Hee University, have proposed a strategy that simultaneously overcomes the limitations of conventional hydrogel-based triboelectric nanogenerators (TENGs)—namely low output performance, poor mechanical strength, and insufficient transparency—by utilizing biomimetic stevia. How stevia transforms hydrogel performance By incorporating stevia into polyvinyl alcohol (PVA), the abundant hydroxyl groups (-OH) simultaneously reinforced the hydrogen bond-based crosslinking structure and crystalline domains, dramatically improving both mechanical strength and ionic conductivity. The work is published in the journal Advanced Materials.

Access to clean water is being strained as the human population increases and contamination impacts freshwater sources. Devices currently in development that clean up dirty water using sunlight can only produce up to a few gallons of water each day. But now, researchers in ACS Central Science report how loofah sponges inspired a sunlight-powered porous hydrogel that could potentially purify enough water to satisfy someone's daily needs—even when it's cloudy.

Previously, researchers have suggested that sunlight-driven evaporation could be a low-energy way to purify water, but this approach doesn't work well when it's cloudy. One solution could be temperature-responsive hydrogels, specifically poly(N-isopropyl acrylamide) (PNIPAm), that switch from absorbing water at cooler temperatures to repelling it when heated. However, conventional PNIPAm gels can't generate clean water fast enough to meet people's daily needs because of their closed-off pores. Conversely, natural loofahs, which many people use to exfoliate in the shower, have large, open and interconnected pores. So, Rodney Priestley, Xiaohui Xu, and colleagues wanted to replicate the loofah's structure in a PNIPAm-based hydrogel, yielding a material that could rapidly absorb water at room temperature, and rapidly release purified water when heated by the sun's rays under bright or cloudy conditions.

Good Suspension

New method of culturing intestinal organoids in suspended basement membrane extract hydrogels enables their production to be scaled up

Read the published research paper here

Image from work by Julia Y. Co and colleagues

Complex in vitro Systems, Safety Assessment, Genentech, South San Francisco, CA, USA

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in Scientific Reports, June 2023

“The method provides a way to catch microplastic particles of a size that the human eye cannot detect. These are particles with a diameter of only 100 nanometers.”

Natural hydrogel can make personal hygiene products greener

A natural, superabsorbent material developed at the University of Waterloo could dramatically reduce the environmental impact of personal hygiene products like diapers, menstrual pads and tampons. Unlike synthetic absorbent materials in commercial hygiene products, which are expected to take centuries to break down, the new hydrogel degrades harmlessly in soil within three months. "Our goal was a scalable, economical process for producing eco-friendly materials to replace the non-degradable components currently used in personal hygiene products," said Dr. Tizazu Mekonnen, a chemical engineering professor at Waterloo. "Our work demonstrates that we can design high-performance alternatives that work extremely well without leaving hundreds of years of waste behind for future generations."

Stiff gels slow germs: Mapping the hydrogel properties that control bacterial growth

Hydrogels are soft, jelly-like materials that can absorb large amounts of water. They are widely used in medical technologies such as contact lenses and wound dressings, and are also a staple of laboratory research, where they are used to grow bacteria. But scientists have long struggled to explain why some hydrogels readily support bacterial growth while others appear to suppress it. Recent research from the University of Warwick, published in Communications Materials, shows that the answer lies not only in the physical properties of the material, particularly its stiffness and hydration, but also on bacterial cell surface characteristics.