First-of-Its-Kind Wearable Patch Wirelessly Detects C-Reactive Protein In Sweat

By HospiMedica International staff writers
Posted on 26 Jun 2023

Image: Wearable wireless sweat patch uses graphene sensor to detect CRP levels (Photo courtesy of Caltech)

Most human diseases and disorders, from arthritis to Zika fever, are characterized by some degree of inflammation. Although inflammation is most commonly associated with symptoms such as pain, redness, and swelling, it is also linked to a range of biochemical markers. One such marker is the C-reactive protein (CRP), produced by the liver. Given its frequent occurrence during inflammation, its presence in the bloodstream is a strong indication of an underlying medical issue. Now, scientists have developed a unique wearable skin sensor that wirelessly detects CRP in human sweat. This sensor could simplify health monitoring for patients and healthcare providers, eliminating the need for more intrusive blood tests.

CRP detection is more challenging compared to other molecules identifiable through sweat sensors, primarily because CRP is found in lower concentrations in the blood than other biomarkers. This is largely due to the larger size of CRP molecules, making their secretion from the bloodstream into sweat more difficult. Additionally, sensitive CRP detection often necessitates particular laboratory steps that wash samples to ensure consistent sensing. The CRP sensor created by researchers at Caltech (Pasadena, CA, USA) is based on laser-engraved graphene, a carbon material in sheet form. This graphene structure houses numerous tiny pores, thereby creating a vast surface area. These pores are infused with antibodies that bind to CRP and special molecules (redox molecules) capable of producing a small electric current under specific conditions.

The sensor also incorporates gold nanoparticles, each carrying a separate set of CRP antibodies (detector antibodies). When CRP molecules enter the sensor through sweat, they latch onto both the detector antibodies on the gold nanoparticles and the antibodies on the graphene. This temporary adhesion of the nanoparticles to the graphene triggers the redox molecule to create an electrical current that can be measured by electronic components connected to the sensor. As each gold nanoparticle carries multiple detector antibodies, they amplify the faint signal that would otherwise be provided by a single CRP molecule. To account for individual variations in sweat compositions that could affect the biosensor's electrochemical signal, the sensor was also engineered to measure the concentration of ions, the pH of the sweat, and skin temperature. This work demonstrates for the first time that sweat CRP can be detected accurately and correlates well with its counterpart in blood, carrying implications for both lab work and practical medical applications.

"This is a general platform that lets us monitor extremely low-level molecules in our body fluids. We hope to expand this platform to monitor other clinically relevant protein and hormone molecules," said Wei Gao, whose lab is responsible for the development of a variety of wearable sweat sensors, including this latest one. "We also want to see if this can be used for chronic disease management. Inflammation means a risk for many patients. If they could be monitored at home, their risk can be identified, and they can be given timely treatment."

Related Links:
Caltech