Finding cancers through the butterfly effect
A camera based on butterfly eyes promises lightweight, rapid and cheap assistance to surgeons. Andrew P Street reports.
Removing cancers from living tissue is a difficult task. Getting at the disease without slicing out healthy cells – or missing targets that will necessitate further surgery down the track – requires skill, patience, experience. Or, alternatively, the ability to see like a butterfly.
A team from the University of Illinois at Urbana-Champaign in the US took the latter route when designing a new surgical camera which can flip between a standard colour image and a near-infrared one which shows up cancerous cells tagged with fluorescent dye.
The model the researchers used was the eye of the morpho butterfly (Morpho menelaus) which, as team leader Viktor Gruev explains in a paper published in the journal Optica, has “eyes [which] contain nanostructures that sense multispectral information [and] can acquire both near-infrared and colour information simultaneously.”
Morpho butterflies are native to Mexico and South and Central America. The genus includes the shimming iridescent blue- and green-winged species that flutter around the Amazon rainforests. They’re especially beloved by collectors, but it turns out their eyes are even more extraordinary than their beautiful colouration.
The researchers explain that the use of fluorescence in detecting cancerous cells is common, but there are problems with existing techniques.
One of the major issues concerns surgeons being able to see the fluorescence in brightly-lit operating theatres, and the consequent need to dim the lights. Another is that current imaging cameras use multiple optical elements for different wavelengths of light, which can easily be knocked out of alignment by something as small as a change in room temperature.
The new system sidesteps the drawbacks by using ta single combined visual system for visual and infrared imagining – just as the butterfly does.
“Their compound eyes contain photoreceptors located next to each other, such that each photoreceptor senses different wavelengths of light in a way that is intrinsically co-registered,” explains to the paper’s lead author, Missael Garcia.
The researchers tested the technique to pinpoint breast cancers in mice, and found it was especially useful in locating cells deep in tissue where surgeons could easily miss the low level of visible fluorescence.
Because the imager is one integrated unit, its size is tiny and it weighs less than a AA battery – which makes it ideal for detecting cancers in hard-to-reach places, such as the prostate and colon.
The units are also extraordinarily cheap to manufacture, costing around $20 each, compare to thousands of dollars required for current imaging set-ups. To that end, the researchers have established a start-up company while working with the US Food and Drug Administration to greenlight the imager for surgery.
Hopefully, the morpho butterflies will get a cut.