Microlaser tells surgeons where to cut

17 Jun 2002

Surgeons may soon be able to remove cancer cells from the body more cleanly with a miniature laser device that incorporates blood cells into the lasing process.

The biological microcavity, or biocavity, laser, patented by researchers at the US Deparment of Energy's Sandia National Laboratories, is only the size of a coin and should allow surgeons to determine very precisely where cancer cells start and stop while they are cutting. This will minimize the amount of healthy tissue removed and will be particularly valuable in sensitive areas like the brain.

The device has already successfully distinguished between cultured cells consisting of normal human brain cells (astrocytes) and their malignant form (glioblastomas) in the laboratory. It can distinguish normal and cancerous cells because cancer cells contain more protein. This makes them more dense and changes their refractive index.

A vertical microlaser beam enters individual cells as they are pushed by a micropump through tiny channels cut into the glass surface of the device and the device measures the speed of the laser light through the cells. In a medical instrument, the microcavity laser would be enclosed in the handle of the surgeon's scalpel and information would be transmitted to a computer by optical fiber.

An algorithm translates the data into a graph in real time, showing surgeons when the blood pumped from the incision has been cleared of cancerous cells.

The Sandia biocavity laser is based on semiconductor fabrication techniques and costs between about USD 10,000 and USD 50,000 to build. This is far cheaper than the conventional flow cytometry techniques and the device works much more quickly so that the surgeon can see the results while he or she is operating. This portable laser device has the potential to provide real time analysis of up to 100,000 cells per second - five times as fast as other methods.

The team is still looking to understand the basic science but is already in discussions with biotechnology companies that are interested in commercializing the technique.

The researchers say that the device could also monitor the biological and chemical constituents of groundwater, waste fluids and explosive chemicals. It is already able to detect other blood protein abnormalities, such as sickle-cell anemia.

SH