Building a biochemistry lab on a chip

February 12, 2013
Cross-section of device with a droplet. The left side shows an unheated droplet with the DNA FRET construct in the double-stranded form. The right side shows a heated droplet where the FRET construct has denatured, resulting in an increase in fluorescence.

(—Miniaturized laboratory-on-chip systems promise rapid, sensitive, and multiplexed detection of biological samples for medical diagnostics, drug discovery, and high-throughput screening. Using micro-fabrication techniques and incorporating a unique design of transistor-based heating, researchers at the University of Illinois at Urbana-Champaign are further advancing the use of silicon transistor and electronics into chemistry and biology for point-of-care diagnostics.

Lab-on-a-chip technologies are attractive as they require fewer reagents, have lower detection limits, allow for parallel analyses, and can have a smaller footprint.

"Integration of various laboratory functions onto microchips has been intensely studied for many years," explained Rashid Bashir, an Abel Bliss Professor of electrical and computer engineering and of bioengineering at Illinois. "Further advances of these technologies require the ability to integrate additional elements, such as the miniaturized , and the ability to integrate heating elements in a massively parallel format compatible with .

"In this work, we demonstrated that we can heat nanoliter volume , individually and in an array, using VLSI silicon based devices, up to temperatures that make it interesting to do various within these droplets."

"Our method positions droplets on an array of individual silicon microwave heaters on chip to precisely control the temperature of droplets-in-air, allowing us to perform biochemical reactions, including DNA melting and detection of single base mismatches," said Eric Salm, first author of the paper, "Ultralocalized thermal reactions in subnanoliter droplets-in-air," published in the (PNAS) on February 12.

According to Salm, approaches to perform localized heating of these individual subnanoliter droplets can allow for new applications that require parallel, time-, and space multiplex reactions on a single integrated circuit. Within miniaturized laboratory-on-chips, static and dynamic droplets of fluids in different immiscible media have been used as individual vessels to perform biochemical reactions and confine the products.

"This technology makes it possible to do cell lysing and nucleic acid amplification reactions within these individual droplets – the droplets are the reaction vessels or cuvettes that can be individually heated," Salm added.

"We also demonstrate that ssDNA probe molecules can be placed on heaters in solution, dried, and then rehydrated by ssDNA target molecules in droplets for hybridization and detection," said Bashir, who is director of the Micro and Nanotechnology Laboratory at Illinois. "This platform enables many applications in droplets including hybridization of low copy number DNA molecules, lysing of single cells, interrogation of ligand–receptor interactions, and rapid temperature cycling for amplification of DNA molecules.

"Notably," Bashir added, "our miniaturized heater could also function as dual heater/sensor elements, as these silicon-on-insulator nanowire or nanoribbon structures have been used to detect DNA, proteins, pH, and pyrophosphates.

By using microfabrication techniques and incorporating the unique design of transistor-based heating with individual reaction volumes, 'laboratory-on-a-chip' technologies can be scaled down to 'laboratory-on-a-transistor' technologies as sensor/heater hybrids that could be used for point-of-care diagnostics."

Explore further: Driving water droplets uphill

More information:

Related Stories

Driving water droplets uphill

April 2, 2008

Lab-on-a-chip technology could soon simplify a host of applications, thanks to a new way to move droplets up vertical surfaces on flexible chips.

Bouncing water droplets reveal small-scale beauty (w/ Video)

October 14, 2010

In the video below, scientists have captured the simple movements of water droplets on a superhydrophobic carbon nanotube surface. The video shows the water droplets as they bounce, slide, and roll across different structures ...

Ultrasensitive biosensor promising for medical diagnostics

May 15, 2012

( -- Researchers have created an ultrasensitive biosensor that could open up new opportunities for early detection of cancer and "personalized medicine" tailored to the specific biochemistry of individual patients.

Researchers create world's smallest reaction chamber

December 6, 2012

The world's smallest reaction chamber, with a mixing volume measured in femtolitres (million billionths of a litre), can be used to study the kind of speedy, nanoscale biochemical reactions that take place inside individual ...

Recommended for you

Mathematicians identify limits to heat flow at the nanoscale

November 24, 2015

How much heat can two bodies exchange without touching? For over a century, scientists have been able to answer this question for virtually any pair of objects in the macroscopic world, from the rate at which a campfire can ...

New sensor sends electronic signal when estrogen is detected

November 24, 2015

Estrogen is a tiny molecule, but it can have big effects on humans and other animals. Estrogen is one of the main hormones that regulates the female reproductive system - it can be monitored to track human fertility and is ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (1) Feb 13, 2013
I want one! Make my interface FireWire or Thunderbolt (bi-directional, peer to peer, lower lag time). Optical as well as the rest of the senses, too.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.