Wearable device can detect individual cells moving in the bloodstream

Wearable device can detect single cells: ©Maksym - stock.adobe.com

Researchers at MIT have developed a device small enough to wear like a smartwatch but powerful enough to detect individual cells moving through the bloodstream. The innovation, called CircTrek, was first published in the online journal npj Biosensing.

Developed by the Nano-Cybernetic Biotrek research group under the direction of Deblina Sarkar, assistant professor at MIT and AT&T Career Development Chair at the MIT Media Lab, CircTrek is designed for continuous, noninvasive monitoring of circulating cells. This real-time insight could revolutionize how physicians diagnose disease, detect relapses, assess infection risk, and monitor the effectiveness of treatments.

Unlike traditional blood tests, which provide only snapshots of a patient's condition, CircTrek was designed to offer a continuous “live feed” from inside the body. Current alternatives such as in vivo flow cytometry can provide some continuous data but require room-sized microscopes and lengthy patient appointments.

CircTrek works by shining a focused laser beam on blood vessels beneath the skin. Cells of interest — such as cancer-fighting CAR T cells — are first labeled using fluorescent dyes or genetic techniques. The laser excites these labeled cells, causing them to emit light that is then detected by the device’s highly sensitive sensors. Importantly, the system filters out low-frequency noise, including heartbeat signals, to isolate the relevant cell data.

The device’s compact circuit board, measuring just 42 mm by 35 mm, contains custom-designed components that maintain stable laser power and reduce electrical noise. Despite its small size, CircTrek’s sensors are sensitive enough to detect a single photon of light — enabling it to register the passage of individual fluorescently labeled cells.

During early in vitro testing that simulated blood flow under the skin, CircTrek successfully identified single cells labeled with Cyanine5.5, a dye optimized for visibility through human tissue. These results were confirmed using high-resolution confocal microscopy. The team also evaluated the laser’s thermal safety, finding that skin temperature rose by just 1.51 degrees Celsius during use — well below thresholds for tissue damage.

In clinical use, CircTrek could track whether CAR T cells remain active in patients with B-cell lymphoma, a factor linked with better treatment outcomes. The device’s Wi-Fi capability also allows for data transmission directly to a patient’s care team — potentially transforming how doctors monitor patients at home.

While more testing is needed before CircTrek reaches patients, researchers are optimistic about its flexibility. The MIT team envisions a future where real-time data from devices like CircTrek enables earlier interventions, personalized treatments, and better outcomes across a wide range of diseases — all from the convenience of a wristwatch-sized wearable.

A legacy of medical device innovation at MIT

The development of CircTrek is the latest in a long line of medical innovations emerging from MIT’s unique ecosystem, where cutting-edge research routinely finds its way into clinical practice. MIT has a storied history of fostering breakthrough technologies that bridge the gap between engineering and medicine, thanks in large part to its strong culture of interdisciplinary collaboration and robust tech transfer programs, according to the school.

Over the past several decades, MIT researchers have been at the forefront of developing life-changing medical devices — from early artificial heart valves and implantable insulin pumps to more recent advances like biocompatible drug delivery systems and robotic surgical tools. Many of these technologies have moved from the lab to the marketplace through strategic partnerships and startups, often incubated within MIT’s entrepreneurial ecosystem.

Key to this success is the Institute’s focus on translational research and its willingness to bring together engineers, clinicians, and business experts to turn ideas into viable products. The MIT Deshpande Center for Technological Innovation and the Koch Institute for Integrative Cancer Research are just two examples of hubs that provide funding, mentorship, and industry connections to help researchers commercialize their discoveries.

This approach has led to a steady stream of spinout companies and licensing agreements that have brought innovative medical technologies to patients worldwide.