Measuring the vital signs of small conscious animals with feathers, fur or scales is no easy task, but Cornell researchers have come up with a solution.
For the first time, Cornell engineers have developed a device that measures the cardiogram and respiration patterns of small animals without touching them. The device works instantaneously from 2 to 3 inches away in a habitat where the animal will likely not notice.
Current technologies – such as electrocardiograms, ultrasound or a stethoscope – require contact with the animal, which can be uncomfortable and stressful. They often require removal of scales, feathers or fur, and in some cases anesthesia is needed.
The new system relies on radio frequency signals, not unlike technology found in smartphones, and was first developed for humans in 2017 before the researchers decided to pursue a device for small animals due to the system’s high sensitivity.
Their study, “No-Touch Measurements of Vital Signs in Small Conscious Animals,” was published Feb. 13 in the journal Science Advances.
“This is the first time ever that we have this ability to monitor a very small conscious animal with no real prep needed when we collect the vital signs,” said Edwin Kan, professor of electrical and computer engineering and the paper’s senior author. Xiaonan Hui, a doctorate student in Kan’s lab, is the paper’s first author.
“It’s so sensitive that we can measure even a faint heartbeat like that of a betta fish,” Kan said.
The researchers say the new technology could be a boon for studying animal biology or behavior. For example, if someone is studying the effects of music on birds, their vital signs could be monitored in real time while music is played. Or, the device could be used to collect long-term measurements of tortoises in hibernation or near-hibernation states, research that is being pursued to inform new strategies for space flight, where astronauts could benefit from entering near-hibernation states.
Small-animal veterinarians could obtain instant vital sign measurements to determine an animal’s stress level, critical information for veterinarians who must act quickly in an emergency.
Kan and Hui have designed active and passive sensors. The passive sensor uses a label-like tag, similar to anti-theft tags used by department stores, that can be placed near an animal. The tags are disposable, inexpensive and can be placed in multiple locations, although a reader must be within 30 feet from a tag to receive the data. The system emits radio waves that bounce off an animal’s body and are picked up by the reader.
The active sensor is a single unit with a battery and an antenna. It can be placed on the cage or aquarium to read the vital signs of the animal, but it’s bulkier than the passive tags, and batteries must be replaced from time to time.
“The active method is easier for an experiment scenario, like in a lab, where it’s easier to deploy,” said Hui. “For the passive version, we can have a large number of tags around the application scenario,” as each tag costs about a dime and can be set with a unique identification code to distinguish readings from one another, Hui said.
Both methods use radio signals to detect movement by “near-field coherent sensing,” which allows the radio signals to penetrate a body to measure motion of internal organs directly.
The system is so sensitive, it can distinguish movements of ventricles and atria. In this way, the direct motion measurements obtained with the device provide more information than a conventional ECG, which collects data from nerve impulses to the heart but needs extensive skin preparation for animals.
The researchers have tested their systems on a conscious hamster (fur), parakeet (feathers), Russian tortoise (shell and scuta) and a betta fish (scales).
The method is protected by provisional patents owned by Cornell University. The study was funded by the U.S. Department of Energy.