Long-term diabetes management requires continuous blood glucose monitoring to detect abnormalities early and intervene in time. However, conventional fingertip blood sampling is both painful and inconvenient, while most continuous glucose monitoring (CGM) products currently available on the market rely on biological enzymes — requiring regular replacement, incurring higher costs, and demanding stringent storage conditions. A research team at The Hong Kong Polytechnic University (PolyU) has developed an enzyme-free, wearable, acoustically readable microneedle patch “ARMPatch”. Once applied to the skin, it can be read by a standard ultrasound probe to continuously reflect changes in blood glucose levels.
The research was led by Prof. SU Zhongqing, Head of the Department of Mechanical Engineering and Chair Professor of Intelligent Structures and Systems at PolyU, together with Prof. MENG Long of the Shenzhen Institutes of Advanced Technology of the Chinese Academy of Sciences, Prof. Jae-Woong JEONG of the Korea Advanced Institute of Science and Technology and their research teams. The findings have been published in Science Advances, with Mr ZHANG Wanglinhan, a PhD student in PolyU’s Department of Mechanical Engineering, as the first author.
Prof. Su said, “The ARMPatch that we have developed serves as a blood glucose monitoring accessory for any regular ultrasound probe, achieving minimally invasive, cost-effective, long-lasting, and stable continuous blood glucose monitoring. This approach offers a novel solution to enzyme-free CGM and expands the application of ultrasound technology in the fields of wearable biosensing and human health monitoring.”
The working principle of the ARMPatch is simple. The patch is made from a glucose-responsive hydrogel based on phenylboronic acid (PBA). Once applied to the skin, its microneedles swell in response to blood glucose fluctuations. The higher the glucose level, the greater the swelling, and ultrasound detects these changes to determine glucose levels. This is precisely what makes the ARMPatch “acoustically readable”.
The team conducted a series of in vitro and in vivo experiments. In vitro, the team demonstrated a good linear response across a glucose concentration range of 0–40 mM, sufficient to effectively monitor hyperglycemia, and delivered stable readings for up to 56 days — far outperforming enzyme-based devices that require frequent replacement.
During in vivo tests, the degree of microneedle swelling read by ultrasound accurately reflected changes in blood glucose levels; the patch successfully monitored blood glucose for seven consecutive days on a freely moving nude mouse, remaining firmly attached and unaffected by the animal’s movement, with no inflammation or scarring on the skin after removal — confirming its biocompatibility and minimally invasive nature.
Many people with diabetes already use portable or wearable ultrasound devices for long-term home monitoring of complications such as heart disease and kidney disease. For them, the ARMPatch requires no additional custom hardware — existing devices can be used to continuously monitor blood glucose.
The team noted that, by adjusting the hydrogel composition, the same platform could in principle be extended to the continuous monitoring of various biomarkers such as pH, proteins, and bacteria. The team hopes to develop microneedle patches that are capable of monitoring multiple indicators simultaneously, turning wearable ultrasound devices into a one-stop tool for home health monitoring.
Prof. Su added, “This study not only presents a novel wearable device that enables conventional ultrasound to be used for enzyme-free CGM, but also opens up a new avenue for monitoring diverse physiological information via standard ultrasound in a minimally invasive manner, using customised hydrogel microneedles.”
This research was supported by the NSFC/RGC Joint Research Scheme along with additional funding from the Research Grants Council of Hong Kong, the National Natural Science Foundation of China, and the National Research Foundation of Korea. The PolyU University Research Facility in Materials Characterization and Device Fabrication and University Research Facility in Life Sciences also provided assistance.
