Analytical Chemistry

To analyze tiny amounts of liquids, scientists often use devices called microfluidic chips, which are small pieces of plastic that are etched or molded with miniscule channels. Although these single-use chips are small, their widespread use in labs, hospitals and point-of-care situations adds up to a lot of plastic pollution. Therefore, researchers reporting in ACS’ journal Analytical Chemistry have developed versatile microfluidic chips made of a renewable, biodegradable and inexpensive resource –– wood.

Microfluidic chips are useful for analyzing small samples, like a single drop of blood, at low cost because only miniscule amounts of expensive reagents are needed. When a fluid flows through the microchannels, it is mixed with certain substances and then analyzed, for example, for the presence of microbes or disease-related proteins. Recently, scientists have tried making microfluidic chips from inexpensive, environmentally friendly resources such as cloth or paper, but these devices are typically limited to relatively simple applications. Govind Rao and colleagues wanted to make a microfluidic device out of low-cost wood that could be used for a variety of purposes.

To make their device, the researchers used a laser printer to engrave tiny channels into birch plywood chips. Then, to prevent liquids from seeping into the porous wood, they coated the channels with a thin layer of Teflon™. When they introduced blue and red food dyes to the tips of Y- and T-shaped patterns of channels, the liquids mixed as efficiently in the wood chips as in conventional plastic devices. The researchers also used the wood chips, in conjunction with a fluorescence technique, to measure the amounts of two proteins and live bacteria, all of which were similar to the amounts determined by a plastic chip. The wood devices were 10–100 times less expensive than comparable plastic ones and more environmentally friendly. Now, the researchers are working on finding a renewable replacement, such as beeswax or natural oils, for the Teflon™ coating.

The authors acknowledge funding from the Defense Advanced Research Projects Agency (DARPA) and the UMBC Technology Catalyst Fund.

Note: ACS does not conduct research, but publishes and publicizes peer-reviewed scientific studies.

Image: Wood microfluidic devices could analyze small amounts of liquids in a more environmentally friendly way. Credit: Adapted from Analytical Chemistry2019, DOI: 10.1021/acs.analchem.9b01232