Ebola-Detection Chip Could Help Save Lives

Posted in Electronic Components by Bob Michaels on December 17, 2014

A microchip-based analyzer detects the presence of Ebola in a few microliters of blood, enabling rapid detection of the virus

Tragically, thousands of people have died from Ebola in the desperately poor countries of Sierra Leone, Liberia, and Guinea. While far from a cure, a portable analyzer fromSTMicroelectronics (Geneva) andClonit, together with with Italy’s National Institute for Infectious Disease Lazzaro Spallanzani, promises to limit the transmission of the virus by detecting it at an early stage.

Based on a real-time polymerase chain reaction (RT-PCR) technique, the analyzer detects the presence of Ebola in a few microliters of blood. Highly sensitive, it can even detect the virus in blood samples diluted up to a million times. The analyzer consists of an extractor on which the sample is loaded to extract the virus’s RNA, reagents for performing a viral load, and a portable optical reader for detecting the presence of viral DNA and sending it to a PC. But the heart of the technology is a microchip developed by STMicro. This chip acts as a miniaturized reactor that amplifies and screens the extracted genetic material on which the extracted RNA is loaded.

“The consumable, stamp-sized silicon microchip is formed in two parts,” explains Maria Teresa Gatti, director of research and innovation, advanced system technology at STMicroelectronics. “The first part is a silicon chip on which resistors are built to perform the thermal cycles needed for the biological reaction. The second is a plastic microgridconsisting of six chambers that are filled with the biological sample and the reagent during the manufacturing process. The two parts are bonded together using a polymer glue.”

Once the consumable is inserted into the optical reader, according to Gatti, a bar code identifies the virus in question—in this case, Ebola. Then, a technician uses a pipette to add the RNA sample extracted from blood and begins the test. The first step of the test takes place at a constant temperature of 50°C to reverse transcript the virus RNA into DNA. The required enzyme is part of the preloaded biological mix. Next, RT-PCR temperature cycling starts, and fluorescence is measured using the optical reader, when appropriate. The result, Gatti adds, is a quantitative measurement of the viral load.

Silicon’s low thermal capacity and the minute volumes of blood tested reduce reaction times significantly and enable fast temperature cycling, enabling quick amplification of biological materials without compromising accuracy and reliability. And PCR’s ability to accurately control the repetitive heating and cooling of the biological material enables the technology to amplify a target biological material such as the Ebola virus contained in a blood sample, enabling its evaluation against biological markers loaded on the microchip.

In collaboration with other industry leaders, the partners are evaluating an integrated, self-contained, and automated disease-detection system that can perform multiple analyses in parallel on a large number of samples. Time optimization, portability, automation, and integration will allow further cost reductions, according to STMicro, and produce a more efficient process, paving the way for affordable Ebola screening.

Bob Michaels is senior technical editor at UBM Canon.