Researchers from the University of Massachusetts Amherst have demonstrated an advance in using graphene for electrokinetic biosample processing and analysis, that could allow lab-on-a-chip devices to become smaller and achieve results faster.
The team developed devices that incorporate microelectrodes made of monolayer graphene. They found that the electrolysis stability over time for graphene microelectrodes is >103Ã improved compared to typical microfabricated inert-metal microelectrodes. Through transverse isoelectric focusing between graphene microelectrodes, within minutes, specific proteins can be separated and concentrated to scales of â¼100 Î¼m.
Based on the concentrating effect and the high optical transparency of graphene, the team developed a three-dimensional multistream microfluidic strategy for label-free detection of the proteins at same processing position with a sensitivity that is â¼102Ã higher than those of the state-of-the-art label-free sensors.
These results demonstrate the advantage of monolayer-graphene microelectrodes for high-performance electrokinetic analysis to allow lab-on-a-chips of maximal time and size efficiencies.
For the detection of biomolecules, we usually first have to isolate them in a complex medium in a device and then send them to another device or another spot in the same device for detection, says Mechanical and Industrial Engineering Department assistant professor Jinglei Ping. "Now we can isolate them and detect them at the same microscale spot in a microfluidic device at the same time.
No one has ever demonstrated this before, he continues. This is owing to our use of graphene, a nanomaterial as thing as a single carbon atom, as microelectrodes in a microfluidic device. We found that, compared to typical inert-metal microelectrodes, the electrolysis stability for graphene microelectrodes is more than 1,000 times improved, making them ideal for high-performance electrokinetic analysis.
Also, Ping added, since monolayer graphene is transparent, we developed a three-dimensional multi-stream microfluidic strategy to microscopically detect the isolated molecules and calibrate the detection at the same time from a direction normal to the graphene microelectrodes.
The new approach developed in the work paves the way to the creation of lab-on-a-chip devices of maximal time and size efficiencies, Ping says. Also, the approach is not limited to analyzing biomolecules and can potentially be used to separate, detect and stimulate microorganisms such as cells and bacteria.