Laserbeamed biochip to detect blood disorders in real time

Albuquerque 28 September 1998 Molecular nanotechnology and nanomedicine seem to sound like magic words. These two revolutionary and innovative scientific concepts involve the art to manipulate atoms in such a way that you can use their characteristics to build fully new materials and objects. As if scientists were to be offered "the finger of God" to create whatever they want. A team of researchers at the Sandia National Laboratory and the National Institutes of Health recently developed a biochip which in a flash detects blood disorders and nanometer-scale changes in cell structure by inserting blood samples into a laser beam generation process. Is this one of the first medical breakthroughs, nanophilosopher Michael Wisz has in mind when expressing his firm belief that "molecular nanotech will come with tiny probes cruising the bloodstream looking for foreign invaders such as viruses and bacteria in a attempt to eliminate most of the infectious diseases"?

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Molecular nanotechnology and nanomedicine seem to sound like magic words. These two revolutionary and innovative scientific concepts involve the art to manipulate atoms in such a way that you can use their characteristics to build fully new materials and objects. As if scientists were to be offered "the finger of God" to create whatever they want. A team of researchers at the Sandia National Laboratory and the National Institutes of Health recently developed a biochip which in a flash detects blood disorders and nanometer-scale changes in cell structure by inserting blood samples into a laser beam generation process. Is this one of the first medical breakthroughs, nanophilosopher Michael Wisz has in mind when expressing his firm belief that "molecular nanotech will come with tiny probes cruising the bloodstream looking for foreign invaders such as viruses and bacteria in a attempt to eliminate most of the infectious diseases"?

The Sandia prototype device is able to track sickle-cell anemia as well as cell particles affected by the AIDs virus. The biochip outperforms the traditional pap smear tests in distinguishing between cancerous and healthy cells. The researchers even can monitor both unrestricted cell growth and cell death or apoptosis. This process of cell suicide is generated in cases where unwanted human tissue has to be removed in order to support the proper growth of organs, limbs and neurons. The new device acts as a lab-on-a-chip, inserting fluids into a micro-laboratory for on the spot display of results. This speed of diagnosis can save many people's lives in situations of terrorist biological or chemical attacks. Under normal conditions, patients no longer need to wait for the results after a blood test.

A vertical-cavity surface-emitting laser (VCSEL) generates millions of tiny laser beams from an area no larger than a postage stamp. The blood cells are introduced in the VCSEL to take part in the creation process of the laser light which is altered while being formed. If no cell is cancerous, the VCSEL emits a standard light signal. Otherwise, the researcher observes a bright flash at different wavelengths. The blood sample is pumped through the etched microgrooves of a coated glass mirror and read out by a light-emitting semiconductor. Therefore, the cells do not have to be killed and stained, like in typical laboratory procedures. In conventional lasers, the sharply cleaved ends are applied as mirrors but the VCSEL semiconductor is not cleaved at all. Instead, it consists of alternating layers of tailored alloys to reflect "in phase" light.

The "in phase" effect creates a highly efficient beam because the minimums and maximums of the generated light occur at the same time. The output light is analysed in a spectrometer to discover the changes in both cell shape and size. The lasing process allows the light to reflect repeatedly through the sample in a way to magnify the deviation in image generated by the blood particle, thus greatly enhancing the chance for an errorless identification. By means of microsurgery, a white blood cell can be opened to observe the proteins it contains, inside the laser cavity. Profound analysis will show how the sample reacts to organisms or drugs in the blood, in order to support the pharmaceutical research.

A laser microscope with the size of a telephone receiver, activates the VCSEL device in wafer form and scans the output as if it were a supermarket bar code. A small, commercial VCSEL biochip already is able to offer a spectral analysis on a laptop computer at a price between $5000 to $15.000. The elaborated laboratory version amounts to $70.000. In the medical VCSEL version, the researchers have replaced the top layers of gallium aluminum arsenide and aluminum arsenide with the microgrooved glass slide in order to transport the blood. The laser beams are changed both by the glass from which they are reflected and the quality of the inserted blood components. For more details on the nanotech biochip, we refer to the Sandia National Laboratory Web site.


Leslie Versweyveld

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