Biochip-based device for cell analysis

May 30, 2012
This is an assembled flow cytometry chip with size comparable to a US quarter. Credit: Tony Jun Huang, Penn State

(Phys.org) -- Inexpensive, portable devices that can rapidly screen cells for leukemia or HIV may soon be possible thanks to a chip that can produce three-dimensional focusing of a stream of cells, according to researchers.

"HIV is diagnosed based on counting ," said Tony Jun Huang, associate professor of engineering science and mechanics, Penn State. "Ninety percent of the diagnoses are done using flow cytometry."

Huang and his colleagues designed a mass-producible device that can focus particles or cells in a single stream and performs three different optical assessments for each cell. They believe the device represents a major step toward low-cost flow cytometry chips for in hospitals, clinics and in the field.

"The full potential of flow cytometry as a clinical has yet to be realized and is still in a process of continuous and rapid development," the team said in a recent issue of Biomicrofluidics. "Its current high cost, bulky size, mechanical complexity and need for highly trained personnel have limited the utility of this technique."

Flow cytometry typically looks at cells in three ways using . Flow cytometers use a tightly focused to illuminate focused cells and to produce three optical signals from each cell. These signals are fluorescence from bound to cells, which reveals the biochemical characteristics of cells; forward scattering, which provides the cell size and its ; and side scattering, which provides cellular granularity. Processingthese signals allows diagnosticians to identify individual cells in a mixedcell population, identify fluorescent markers and count cells and other analysis to diagnose and track the progression of HIV, cancer and other diseases.

"Current machines are very expensive costing $100,000," said Huang. "Using our innovations, we can develop a small one that could cost about $1,000."

One reason the current machines are so large and expensive is the method used to channel cells into single file and the necessary alignment of lasers and multiple sensors with the single-file cell stream. Currently, cells are guided into single file using a delicate three-dimensional flow cell that is difficult to manufacture. More problematic is that these current machines need multiple lenses and mirrors for optical alignment.

"Our approach needs only a simple one-layer, two-dimensional flow cell and no optical alignment is required," said Huang.

Huang and his team used a proprietary technology named microfluidic drifting to create a focused stream of particles. Using a curved microchannel, the researchers took advantage of the same forces that try to move passengers in a car to the outside of a curve when driving. The microfluidic chip's channelbegins as a main channel that contains the flow of carrier liquid and a second channel that comes in perpendicularly that carries the particles or cells. Immediately after these two channels join, the channel curves 90 degrees, which moves all the cells into a horizontal line. After the curve, liquid comes into the channel on both sides, forcing the horizontal line of cells into single file. The cells then pass through a microlaser beam.

An advantage of this microfluidic flow cytometry chip is that it can be mass-produced by molding and standard lithographic processes. The fibers for the optical-fiber delivered laser beams and already exist.

"The optical fibers are automatically aligned once inserted into the chip, therefore requiring no bulky lenses and mirrors for optical alignment," said Huang. "Our machine is small enough it can be operated by battery, which makes it usable in Africa and other remote locations."

The researchers tested the device using commercially available, cell-sized fluorescent beads. They are now testing the device with actual .

Explore further: SI traceability for mercury vapour measurement in air

Related Stories

Liquid lens creates tiny flexible laser on a chip

May 11, 2009

(PhysOrg.com) -- Like tiny Jedi knights, tunable fluidic micro lenses can focus and direct light at will to count cells, evaluate molecules or create on-chip optical tweezers, according to a team of Penn State engineers. ...

Study adds timing capability to living cell sensors

Feb 08, 2012

(PhysOrg.com) -- Individual cells modified to act as sensors using fluorescence are already useful tools in biochemistry, but now they can add good timing to their resumé, thanks in part to expertise ...

Acoustic tweezers can position tiny objects

Aug 28, 2009

(PhysOrg.com) -- Manipulating tiny objects like single cells or nanosized beads often requires relatively large, unwieldy equipment, but now a system that uses sound as a tiny tweezers can be small enough ...

Recommended for you

Water leads to chemical that gunks up biofuels production

44 minutes ago

Trying to understand the chemistry that turns plant material into the same energy-rich gasoline and diesel we put in our vehicles, researchers have discovered that water in the conversion process helps form ...

Celebrating 100 years of crystallography

6 hours ago

To commemorate the 100th anniversary of a revolutionary technique that underpins much of modern science, Chemical & Engineering News (C&EN) magazine last week released a special edition on X-ray crystallography—its past, ...

Treating pain by blocking the 'chili-pepper receptor'

7 hours ago

Biting into a chili pepper causes a burning spiciness that is irresistible to some, but intolerable to others. Scientists exploring the chili pepper's effect are using their findings to develop a new drug ...

Testing the shelf-life of nuclear reactors

7 hours ago

Researchers at the University of Michigan, Ann Arbor, Los Alamos National Laboratory, Idaho National Laboratory, Idaho Falls and TerraPower based in Bellevue, Washington, have demonstrated the power of high-energy beams of ...

User comments : 0