IBM creates rapid diagnostic testing system on a chip

18 November 2009

Researchers at IBM's Zurich labs  have created a point-of-care diagnostic test system based on microfluidics on a silicon chip. The lab-on-a-chip requires less sample volume, is significantly faster, portable, easy to use and can test for many diseases.

The system analyzes tiny samples of blood for the presence of disease markers, which are typically proteins. Specific antibodies with a fluorescent tag bind to the disease marker and are then captured in a special chamber on the chip where they can be detected using a focused beam of light.

The device was developed using IBM's expertise in silicon chip technology, surface chemistry, and nanotechnology.

The results are so quick and accurate that a patient’s serum or blood sample could be tested immediately following a heart attack, to enable the doctor to quickly take a course of action and to predict the patients survival rate.

IBM Research - Zurich scientists Luc Gervais and Emmanuel Delamarche, in collaboration with the University Hospital of Basel in Switzerland, have developed the new lab-on-a-chip.

"This point of care test has achieved the trifecta for medical staff in that it is portable, fast and requires a very small volume of sample," comments Emmanuel Delamarche, scientist, IBM Research — Zurich. "We are giving back precious minutes to doctors so they can make informed and accurate decisions right at the time they need them most to save lives".

All in the chip

The chip, which measures 1 × 5 cms, contains sets of micrometer wide channels where the test sample flows through by capillary action in approximately 15 seconds, several times faster then traditional tests. Uniquely, the filling speed can be adjusted to several minutes by using different microfluidic designs, when additional time is needed to read a more complex disease marker.

The diagnostics system consists of five innovative stages:

•  Stage 1: A one microliter sample, 50 times smaller than a tear drop, is pipetted onto the chip, where the capillary forces begin to take effect;
•  Stage 2: These forces push the sample through an intricate series of mesh structures, which prevent clogging and air bubbles from forming;
•  Stage 3: The sample then passes in a region where microscopically small amounts of the detection antibody have been deposited. These antibodies have a fluorescent tag and similar to the antibodies within our body, they recognize the disease marker and attach to it within the sample. Only seventy picoliters (a volume one million times smaller than a tear) of these antibodies are used, making their dissolution in the passing sample extremely fast and efficient.
•  Stage 4: The most critical stage is called the "reaction chamber" and it measures 30 micrometers in width and 20 micrometers in depth, roughly the diameter of a strand of human hair. Similar to a common pregnancy test, in this stage the disease marker that was previously tagged is captured on the surface of the chamber. By shining a focused beam of red light, the tagged disease markers can be viewed using a portable sensor device that contains a chip similar to those used by digital cameras, albeit this one being much more sensitive. Based on the amount of light detected, medical professionals can visually confirm the strength of the disease marker in the sample to determine the next course of treatment.
•  Stage 5: Less a stage and more a part of the entire process is the capillary pump. The capillary pump, which has a depth of 180 micrometers, contains an intricate set of microstructures, the job of which is to pump the sample through the device for as long as needed and at a regular flow rate, just like the human heart. This pump makes the test accurate, portable and simple to use. IBM scientists have developed a library of capillary pumps so that tests needing a variety of sample volumes or test times can still be done without having to re-engineer the entire chip.

Going to market

True to IBM's strategy of open collaboration, scientists in Zurich followed a “bench to bedside” strategy where ideas from their lab were tested with academic and healthcare partners. This research also would not have been possible without the generous support of KTI/CTI, an organization which fosters innovation in Switzerland.

"This microfluidic chip is the next step in the evolution of point of care devices. We look forward to working with the scientists at IBM Research - Zurich to develop this innovation even further," said Thierry Leclipteux, Chief Executive Officer and Chief Science Officer, Coris BioConcept.

IBM scientists designed the chip with flexibility in mind in both its form and uses. Due to its small size the chip can be embedded in several types of form factors, depending on the application, including a credit card, a pen or something similar to a pregnancy test. Besides diagnosing diseases, the test is also flexible enough to test for chemical and bio hazards.

IBM video on the lab-on-a-chip