The transformation process also known as gelation plays an important role across many industries, including cosmetics where manufacturers add chemical thickeners and either heat or cool the fluids to make them more viscous or elastic, which can be expensive and energy demanding.
Researchers can add nanoparticles or biomolecules with useful pH, chemical, and temperature sensing properties into a liquid, but incorporating those liquids into existing technology proves difficult.
Take shampoo, for example. Without gelation, the contents of the shampoo bottle would be thin and watery.
Thus, graduate University Professor Amy Shen led the Micro/Bio/Nanofluidics Unit at OIST in experimenting with a new method of gelation to change the way liquids behave using microfluidic platforms.
These are flat, palm-sized trays with microscopic channels for the liquid to pass through.
Encapsulated glucose oxidase
To induce gelation, Shen’s lab first molds a microfluidic platform out of transparent rubber, creating grooved channels through which liquid can travel before pumping a watery and soapy mixture through the platform, which emerges from the other side as a thick gel.
The mixture is then manipulated to adjust the number of oblong aggregates, so that they look like long, skinny worms before passing through the microfluidic platform, which thanks to its' structure allows these aggregates to fuse and further tangle together, which gives the gel its stiffer, more viscous and elastic properties.
"A gel is easier to integrate into a device, whereas liquid just evaporates,” Shen explains.
“In this way, we are able to change phase from water to something more like hair gel,” she adds, estimating that her method requires just half of the chemicals that traditional gelation processes require.
For their Lab on a Chip publication, the team created a gel that encapsulated glucose oxidase, or GOx, an enzyme that is frequently used in glucose test strips because it generates a measurable electric signal in response to glucose.
They then showed that the gel could use a single gel scaffold to accurately sense blood glucose levels over a much wider range than current glucose sensing technology. The gel contains water, which prevents the GOx enzyme from drying out, thus stabilizing it better than current glucose test strips.
Furthermore, Shen and her lab can create the gel under room temperature and ambient pressure, both critical to maintaining GOx’s functionality.