One-Step POC Diagnostic Test Based on Silicon Chip

The new diagnostic test uses capillary forces to analyze tiny samples of serum, or blood, for the presence of disease markers, which are typically proteins that can be detected in people's blood for diagnostic purposes.

The device uses integrated microfluidic elements and reagents such as detection antibodies, capture antibodies, and analyte molecules for performing one-step immunoassays. The addition of a sample triggers a cascade of events powered by capillary forces for accomplishing a sandwich immunoassay that is read using a fluorescence microscope.

IBM Research-Zurich (Switzerland) scientists Luc Gervais and Emmanuel Delamarche, in collaboration with the University Hospital of Basel (Switzerland) developed the new test. The IBM scientists encoded the forces of capillary action on a microfluidic chip made of a silicon compound, similar to those used in computer chips. The chip contains sets of micrometer wide channels through which the test sample flows in approximately 15 seconds, several times faster then traditional tests. The filling speed can be adjusted to several minutes when the chip requires additional time to read a more complex disease marker.

The diagnostic test has been studied on heart disease but the scientists believe that it could be used to diagnose any disease that markers have been developed for, such as: breast cancer, prostate cancer, lung cancer, human immunodeficiency virus (HIV), hepatitis C virus (HCV), Influenza virus (including the H1N1 strain and others), Epstein-Barr virus (EBV), and bacterial infections, such as Escherichia coli. The test works by recognizing antibodies; therefore, as long as the patient's body has begun to fight the disease by developing antibodies, it should be able to identify the disease.

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 sufficiently flexible to test for chemical and biohazards.

The test is described in the online version of the December 7, 2009 issue of the journal Lab on a Chip.

Related Links:
IBM Research-Zurich
University Hospital of Basel