Bluetooth Microscope Reveals the Inner Workings of Mice

This article is part of our exclusive IEEE Journal Watch series in partnership with IEEE Xplore.

Any imaging technique that allows scientists to observe the inner workings of a living organism, in real-time, provides a wealth of information compared to experiments in a test tube. While there are many such imaging approaches in existence, they require test subjects—in this case rodents—to be tethered to the monitoring device. This limits the ability of animals under study to roam freely during experiments.

Researchers have recently designed a new microscope with a unique feature: It’s capable of transmitting real-time imaging from inside live mice via Bluetooth to a nearby phone or laptop. Once the device has been further miniaturized, the wireless connection will allow mice and other test subject animals to roam freely, making it easier to observe them in a more natural state.

“To the best of our knowledge, this is the first Bluetooth wireless microscope,” says Arvind Pathak, a professor at the Johns Hopkins University School of Medicine.

Through a series of experiments, Pathak and his colleagues demonstrate how the novel wireless microscope, called BLEscope, offers continuous monitoring of blood vessels and tumors in the brains of mice. The results are described in a study published 24 September in IEEE Transactions on Biomedical Engineering.

Microscopes have helped shed light on many biological mysteries, but the devices typically require that cells be removed from an organism and studied in a test tube. Any opportunity to study the biological process as it naturally occurs in the in the body (“in vivo”) tends to offer more useful and thorough information.

Several different miniature microscopes designed for in vivo experiments in animals exist. However, Pathak notes that these often require high power consumption or a wire to be tethered to the device to transmit the data—or both—which may restrict an animal’s natural movements and behavior.

“To overcome these hurdles, [Johns Hopkins University Ph.D. candidate]Subhrajit Das and our team designed an imaging system that operates with ultra-low power consumption—below 50 milliwatts—while enabling wireless data transmission and continuous, functional imaging at spatial resolutions of 5 to 10 micrometers in [rodents],” says Pathak.

The researchers created BLEscope using an off-the-shelf, low-power image sensor and microcontroller, which are integrated on a printed circuit board. Importantly, it has two LED lights of different colors—green and blue—that help create contrast during imaging.

“The BLE protocol enabled wireless control of the BLEscope, which then captures and transmits images wirelessly to a laptop or phone,” Pathak explains. “Its low power consumption and portability make it ideal for remote, real-time imaging.”

Pathak and his colleagues tested BLEscope in live mice through two experiments. In the first scenario, they added a fluorescent marker into the blood of mice and used BLEscope to characterize blood flow within the animals’ brains in real-time. In the second experiment, the researchers altered the oxygen and carbon dioxide ratios of the air being breathed in by mice with brain tumors, and were able to observe blood vessel changes in the fluorescently marked tumors.

“The BLEscope’s key strength is its ability to wirelessly conduct high-resolution, multi-contrast imaging for up to 1.5 hours, without the need for a tethered power supply,” Pathak says.

However, Pathak points out that the current prototype is limited by its size and weight. BLEscope will need to be further miniaturized, so that it doesn’t interfere with animals’ abilities to roam freely during experiments.

“We’re planning to miniaturize the necessary electronic components onto a flexible light-weight printed circuit board, which would reduce weight and footprint of the BLEscope to make it suitable for use on freely moving animals,” says Pathak.

This story was updated on 14 October 2024, to correct a statement about the size of the BLEscope.

This article appears in the January 2025 print issue as “Bluetooth Microscope Peers Inside Live Mice.”