The "Smart Necklace" biosensor can track health through sweat
Participants riding stationary bicycles produced enough sweat for the study's sensor analysis.
Researchers have successfully tested a device that could one day use chemical biomarkers in sweat to detect changes in a person's health.
In a new study published in the journal Science Advances, a team at Ohio State University demonstrated a battery-free wireless biochemical sensor that can detect blood sugar or glucose excreted from the skin as the human body exercises.
The design and working principle of wireless biochemical sensors inspired by tuning circuits.
( A ) Schematic diagram of stretchable, battery-free sensors and envisaged applications of sensor systems for the detection of various biomarkers in body fluids. ISF, interstitial fluid. ( B ) Photo of the wireless sensor. (C) Equivalent circuit and flowchart of the signal conversion and transmission process of the sensor system. (D and E) measurement and simulation with DC reverse bias (from 200 to 400 mV; Step: 50 mV) of the offset of the resonant curve of the sensor. Measurements and simulation results of fs as a function of inverse bias (inset: enlarged view).
The Ohio State university team made a "smart necklace" — complete with a functional clasp and pendant — that, once worn around the neck, monitored study participants' blood sugar levels as they exercised.
Instead of using a battery, it operates using a resonant circuit that reflects an RF signal emitted by an external reader system. After a 30-minute indoor cycling session, participants took a 15-minute break, during which they drank a sugary drink and then started cycling again.
Study co-author Jinghua Li, an assistant professor of materials science and engineering at Ohio State University, said the researchers knew that glucose levels in sweat increased after drinking a sugary drink — the question is whether the new sensor would detect it.
The results showed that the sensor did succeed in tracking glucose levels, suggesting that it could monitor other important chemicals in sweat.
"Sweat actually contains hundreds of biomarkers that can reveal very important information about our health," Lee said. "The next generation of biosensors will be highly bio-intuitive and non-invasive, and we will be able to detect the critical information contained in human body fluids."
Biomarkers are substances that can reveal the body's deepest secrets: evidence of disease, infection, and even emotional trauma can be found in a person's bodily fluids, including sweat, tears, saliva, and urine. In addition to analyzing the composition of sweat, the researchers believe that such sensors could one day be customized as biological implants and used to detect neurotransmitters and hormones, which could help identify ion disorders in the cerebrospinal fluid associated with secondary brain injury, and even lead to a new kind of li said, understanding the function of the brain.
In addition, due to the miniaturized structure of the sensing interface, this smart necklace can make the interface work with minimal sweat, Li added.
Although it will take some time for devices similar to the prototype of this study to be made available to the public, Lee is already considering what will benefit people who need this potentially life-saving technology the most.
Demonstration of bio-integrated chemical sensors tailored for different application scenarios.
( A ) Intelligent necklace design and schematic based on a tuning circuit-inspired sensor prototype, including pendants, clasps, and chains. ( B ) Photo of participants wearing a smart necklace for sweat analysis while riding a bicycle. ( C ) Calibration diagram of a smart necklace for field testing. (D) Two participants wirelessly collected signals in real time during cycling and corresponding data obtained using commercial glucose determination kits showing changes in glucose concentrations in sweat. (E) Comparison of glucose concentrations measured by smart necklaces and commercial test kits. Data are from the 20 sweat samples shown in (D), excluding the first point of each study section used for baseline correction. ( F ) Schematic of a miniature sensor probe based on a resonant circuit that can be used as a biological implant. (G) Comparison between miniaturized sensor probes and competing state-of-the-art wireless sensing technologies. (H and I) photographs of miniature coupling units mounted on fingertips and integrated with a piece of meat, respectively. (J and K) Electrical performance of small probes with input reverse bias of analog biochemical signals.
Instead of using bulky and hard computer chips found in our phones and laptops, the sensors are made of ultra-thin materials. This design style gives the product a high degree of flexibility, protects the functionality of the device, and ensures that it can come into safe contact with human skin.
While the study notes that further miniaturization will make such devices and similar devices easier to implant, for now, Li says she sees it as a lightweight device with a simple circuit layout that can be easily integrated into our daily lives.
"We hope that eventually these sensors can be seamlessly integrated into our personal belongings," she said. "Some of us may wear necklaces, some may wear earrings or rings. But we believe these sensors can be placed on something we all wear, and it can help us better track our health. ”