Researchers have created a completely self-contained fingertip-sized microscope to take pictures of the goings-on in the brain of a mouse as it goes about its normal, mousy day.
In particular, it’s a fluorescence microscope (pictured) that can image all sorts of things from blood flow to brain activity. One day, it could be used for image-based screening to detect signs of disease.
At 1.9 grams, the microscope is tiny enough to be arranged in arrays of many microscopes for parallel imaging of many samples. And it’s sturdy enough to be carried on the head of a mouse, making it a robust field instrument where access to conventional scopes are limited.
The team, led by Stanford’s Mark Schnitzer, injected mice with a fluorescent dye to mark molecules in their brains. Then they mounted the microscope atop the mice’s heads, and then let them walk around and run on a wheel.
"It's like a little high tech hat," Schnitzer says.
They were able to see the dilation of capillaries in mouse brains and the firing of motor-activity-related Purkinje neurons, Nature News explains. That’s up to 200 brain cells.
"You could put 10 of these in your pocket and take them out to the field to do ecological studies of soil or give them to aid workers to carry, so they could potentially do on-the-spot medical screening for diseases such as tuberculosis," Schnitzer says.
Some other features:
- The maximum resolution is 2.5 microns, so it isn’t as powerful as conventional bench-top models that have resolutions as fine as 0.5 microns; but the mouse-top model has a larger field of view than some.
- Other methods of looking inside the brains of animals, such as with MRIs or bench-top scopes, requires holding the animals firmly in place. Of course that’s not their natural behavior.
- Also, it’s usually difficult to study many animals at the same time, but the new device is computer-controlled, and the images it gathers are viewed on a monitor.
- It has no moving parts, and it’s sealed against dust.
- It’s built using entirely mass-producible parts. While mini versions of the same thing have been made before, this one "contains all the optical parts within a single, small and easily-transportable housing, and we use mass-fabricated components, which opens up the possibility of mass-producing the entire microscope," Schnitzer says.
He and colleagues founded a company called Inscopix to capitalize on their device.
They estimate that the light source and camera would cost between $1 and $10 each – compared with $25,000–50,000 for a scientific-grade camera – and that all the other optical parts, such as microlenses and filters, could also be mass-produced.
These diminutive new devices are made possible, according to Technology Review, in large part by the rapidly falling cost and size of electronics components – a trend that has in turn been driven by the demand for consumer devices, like cellphones.
The study was published in Nature Methods earlier this month.
Image: Dan Stober, Stanford News Service