The surgeon’s knife is about to becone a lot more precise thanks to the development of a `smart’ scalpel that is able to detect the presence of cancer cells.
Invented by scientists at the US government’s Sandia National Laboratories in Albuquerque, the tiny device, known as a biological microcavity laser, will help surgeons cut away malignant tissue more accurately by indicating when they should stop cutting.
During a surgical operation, an aspirator vacuums fluid from the incision to the microcavity laser enclosed in the scalpel’s handle, where a vertical microlaser beam shines through individual cells as they are pushed by a pump through tiny channels in the glass surface of the device.
Since cancerous cells contain more protein than normal cells, their additional density changes the speed of the laser light passing through them. This change is registered by a receiver and transmitted by optical fibre to a laptop computer.
An algorithm translates the data into a dynamic graph that provides surgeons with easily read peaks and valleys that indicate when blood pumped from the incision has been cleared of cancerous cells.
`We can quickly identify a cell population that has abnormal protein content by passing only a few hundred cells – a billionth of a litre – through our device,’ says Paul Gourley, leader of the Sandia team that developed the laser.
The smart scalpel, which is quicker and cheaper than the traditional flow cell cytometer, is a result of Sandia’s extensive work on compound semiconductor materials and microcavity laser structures.
The new tool was made possible thanks to a breakthrough at the Sandia laboratories 14 years ago, when researchers succeeded in joining nanometre-thick layers of crystalline materials together to form a vertical cavity laser in the form of a single lattice.
This made it possible to create tiny, efficient lasers out of semiconductors in which layers of gallium aluminum arsenide are sandwiched between layers of gallium arsenide.
Energising the middle layer makes it emit photons, while the layers above and below it act as mirrors which reflect the photons back and forth and pull them all into phase to produce laser light.
Biotechnology companies are already showing interest in commercialising the technique.
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