Technological Advances of Wearable Device for Continuous Monitoring of In Vivo Glucose

Skin-interfaced sweat monitoring patch constructed by flexible microfluidic capillary pump and Cu-MOF sensitized electrochemical sensor

The limitations of skin-interfaced sweat monitoring are mainly reflected in the effective collection of sweat and the high sensitivity of the detection. This work proposes a new type of sweat monitoring patch based on a flexible microfluidic chip fabricated by a capillary pump and a copper-based metal-based organic framework (Cu-MOF) sensitized electrochemical sensor. The sweat in the microchannel is driven by a capillary pump to ensure the smooth collection and transportation. The sweat collection channel adopts the ingenious design of wedge-shaped structure, which helps to spontaneously generate Laplacian forces to direct sweat to the detection area. The detection area combines upper and lower capillary pumps, which aim to improve the efficiency of sweat collection. The controllable preparation of Cu-MOF was realized by using a micro-mixer, and the glucose sensor was prepared with it as the probe. The Cu-MOF/PANI layered electrode was prepared, which effectively improved the sensitivity of glucose detection and achieved a significant detection limit of 2.84 μM in the concentration range of 0-1 mM. Sodium and potassium selective electrode were also integrated into a unified screen-printed electrode, and a portable electrochemical detection module, a Bluetooth transmission module, and a mobile phone receiving application were developed. The sweat monitoring patch shows potential in applications such as sports performance monitoring, healthcare, and personalized medicine, opening new avenues for non-invasive health monitoring and early disease detection.

Support-Free Implantable Photoelectrochemical Hydrogel Fiber Enables Long-Term Monitoring in Free-Behaving Organisms

The development of long-term and in situ in vivo monitoring techniques is critical for environmental biology, life sciences, and analytical chemistry. However, existing in vivo analysis methods are limited by the complex and large instruments or adverse impacts of rigid implanted substrates on living organisms, making it difficult to achieve continuous in situ detection. Herein, taking advantage of the flexibility and biocompatibility of the hydrogel fiber and solving its instability or opacity problems caused by ionic or polymer conduction for hydrogel fibers, a photoelectrochemical (PEC) hydrogel fiber free of conventional rigid substrate support is successfully prepared and achieves long-term tracking of persistent organic pollutants in free-behaving fish, timely identifying their environmental ecological risks. This support-free PEC fiber exhibits fascinating properties of electrical and light conductivity, flexibility, antifouling ability, and biocompatibility, allowing it to be implanted in vivo for 70 days without experiencing significant loss of sensing performance and causing apparent inflammation and immune responses. Moreover, the fabricated fiber not only achieves in vitro pentachlorophenol detection with high selectivity, low detection limit, good reproducibility, and dual-mode sensing but also realizes in vivo monitoring of pentachlorophenol enriched in fish brain for up to 70 days with satisfactory reliability, unraveling its tempting potential for various in vivo application.

Recent progress on glucose dehydrogenase: multifaceted applications in industrial biocatalysis, cofactor regeneration, glucose sensors, and biofuel cells

Glucose dehydrogenase (GDH) is an enzyme that catalyzes the oxidation of glucose. Through the oxidation process, glucose is converted into gluconic acid, releasing electrons in the process, which plays a crucial role in various biological and industrial applications. GDH is widely applied in molecular biology, medicine, and industry. Currently, glucose dehydrogenase is a core component in glucose test strips, commonly used in blood glucose monitoring. Additionally, due to its catalytic properties, GDH is also employed in industrial biocatalysis, coenzyme regeneration, synthetic biology, and biofuel cells. Despite being studied for many years and having achieved industrial applications in glucose biosensors, advanced research and development on glucose dehydrogenase still continues. In recent years, more attention has been focused on improving the enzyme's performance through molecular engineering or novel immobilization techniques, as well as expanding its application fields. These efforts aim to enhance the enzyme's contribution to global challenges, such as human health diagnostics, industrial biocatalysis upgrades, and the development of bioenergy. This review summarizes the recent advancements in glucose dehydrogenase research, focusing on enzyme molecular engineering and performance enhancement, novel immobilization strategies, and the latest applications in biosensors, biocatalysis, and biofuel cells.

Advancements in Wearable and Implantable BioMEMS Devices: Transforming Healthcare Through Technology

Wearable and implantable BioMEMSs (biomedical microelectromechanical systems) have transformed modern healthcare by enabling continuous, personalized, and minimally invasive monitoring, diagnostics, and therapy. Wearable BioMEMSs have advanced rapidly, encompassing a diverse range of biosensors, bioelectronic systems, drug delivery platforms, and motion tracking technologies. These devices enable non-invasive, real-time monitoring of biochemical, electrophysiological, and biomechanical signals, offering personalized and proactive healthcare solutions. In parallel, implantable BioMEMS have significantly enhanced long-term diagnostics, targeted drug delivery, and neurostimulation. From continuous glucose and intraocular pressure monitoring to programmable drug delivery and bioelectric implants for neuromodulation, these devices are improving precision treatment by continuous monitoring and localized therapy. This review explores the materials and technologies driving advancements in wearable and implantable BioMEMSs, focusing on their impact on chronic disease management, cardiology, respiratory care, and glaucoma treatment. We also highlight their integration with artificial intelligence (AI) and the Internet of Things (IoT), paving the way for smarter, data-driven healthcare solutions. Despite their potential, BioMEMSs face challenges such as regulatory complexities, global standardization, and societal determinants. Looking ahead, we explore emerging directions like multifunctional systems, biodegradable power sources, and next-generation point-of-care diagnostics. Collectively, these advancements position BioMEMS as pivotal enablers of future patient-centric healthcare systems.

A Patient-Centered Approach in Sensor Science: Embracing Patient Engagement for Translational Clinical Technologies

With the goal of impacting patient quality of life and outcomes, sensor science offers significant potential to revolutionize healthcare by providing advances in the detection of molecular biomarkers for personalized clinical technologies. The sensor community has achieved significant technical advancements that can impact diagnostics, health monitoring, and disease treatment; however, many sensor innovations remain confined to the laboratory, failing to bridge the translational gap between research and real-world clinical applications. This perspective presents a new direction for the sensor community, where sensor development centers on the needs and experiences of the primary beneficiaries: the patients. We provide guidelines and resources for researchers to engage with patients early and continuously throughout the research process to inform sensor specifications and better align sensor technologies with real-world clinical needs, improving their adoption and impact. We also present examples for implementing a patient-centered approach in sensor development and planning for patient engagement in sensor research. In the design of impactful sensors for patients, researchers must expand focus beyond technical specifications to embrace a patient-centered approach, which will likely lead to new opportunities for collaboration and evolution in the sensor science community.

BSA/PEI/GOD modified cellulose nanocrystals for construction of hydrogel-based flexible glucose sensors for sweat detection

With the miniaturization, integration and intelligence of sweat electrochemical sensor technology, hydrogel flexible sensors have demonstrated immense potential in the field of real-time and non-invasive personal health monitoring. However, it remains a challenge to integrate excellent mechanical properties, self-healing properties, and electrochemical sensing capabilities into the preparation of hydrogel-based flexible sensors. The utilization of CBPG (cellulose nanocrystals (CNCs)@bovine serum albumin (BSA)@polyethyleneimine (PEI) glucose oxidase (GOD) nanomaterial) as both an enhancing phase and sensor probe within a hydrogel matrix, with poly(vinyl alcohol) (PVA) serving as the primary network constituent, has been proposed as a non-invasive technique for monitoring trace glucose levels in sweat. In this study, BSA was initially attached to CNCs through electrostatic interactions. To further boost the surface active sites of the nanomaterial (CNCs@BSA), PEI was grafted onto the nanomaterial surface. The resulting CNC@BSA@PEI nanomaterials were then used as carriers for GOD. The prepared hydrogel exhibited good self-healing properties (87.5%) and excellent breaking strength (0.8 MPa), effectively converting glucose stimulation in human sweat into electrical output. The sensor had a detection range of 1.0-100.0 μM and a detection limit as low as 0.9 μM. Due to its ability to specifically recognize trace glucose levels in sweat, the CBPG-PVA sensor can perform highly selective, flexible, and reliable real-time monitoring of human sweat, offering significant potential for wearable biofluid monitoring in personalized health applications.

A high-sensitivity continuous glucose sensor using porous 3D cellulose/ carbon nanotube network

While numerous needle-based continuous glucose monitoring (CGM) devices have been available today, the insufficient enzyme immobilization on monitoring sensor severely limited the detection sensitivity of CGM devices. This manuscript describes here a high-sensitivity continuous glucose sensor (CGS) by engineering a porous 3D cellulose/carbon nanotube (CNT) network on the working electrode, which subcutaneously increases the detection enzyme capacity and thus significantly enhances the signal intensity and sensitivity. Furthermore, a tapered needle made of soft resin is engraved into three distinct microgrooves where the glucose oxidase (GOD)-modified working electrode, Pt-modified counter electrode, and Ag/AgCl-modified reference electrode are separately constructed inside the microgrooves. Moreover, a miniature potentiostat tailored for signal acquisition, processing, and transmission is engineered. After incorporated with a wireless circuit, the proposed CGS achieves continuous glucose monitoring in interstitial fluid with a surprising sensitivity of 9.15 μA/mM/cm2, as well as maintaining functionality for a period of up to 9 days in live rats. This work provides the public a high-sensitivity continuous glucose monitoring device.

Toward At-Home and Wearable Monitoring of Female Hormones: Emerging Nanotechnologies and Clinical Prospects

Steroid hormones, especially progesterone (P4), estradiol (E2), and testosterone (T), are key bioactive regulators in various female physiological processes, including growth and development, ovulation, and the reproductive cycle, as well as metabolism and mental health. As lipophilic molecules produced in sex glands, these steroid female hormones can be transported through blood vessels into various body fluids such as saliva, sweat, and urine. However, the ultralow concentration of steroid hormones down to picomolar (pM) level necessitates great demands for ultrasensitive but low-cost analytic tools to implement accurate, point-of-care or even continuous monitoring in a user-friendly fashion. This review focuses on the latest advances in materials and nanotechnologies to allow the rapid detection of female hormones at the pM level or below and the potentials in at-home and wearable hormone monitoring. We specifically summarize the optical and electrochemical strategies in this category, particularly those affording low cost and portable signal readout for at-home use. Furthermore, emerging flexible/wearable innovations are highlighted, which allow the continuous hormone cycle tracking in a noninvasive manner. The potential of these techniques is discussed to address the need for real-time acquisition of the hormone fluctuation, facilitating health monitoring at home. Lastly, we provide a comprehensive introduction to the prospects of female hormone monitoring in clinical diagnosis and treatment, from the perspective of gynecology and reproductive medicine clinicians.

Wearable Electrochemical Biosensors for Advanced Healthcare Monitoring

Recent advancements in wearable electrochemical biosensors have opened new avenues for on-body and continuous detection of biomarkers, enabling personalized, real-time, and preventive healthcare. While glucose monitoring has set a precedent for wearable biosensors, the field is rapidly expanding to include a wider range of analytes crucial for disease diagnosis, treatment, and management. In this review, recent key innovations are examined in the design and manufacturing underpinning these biosensing platforms including biorecognition elements, signal transduction methods, electrode and substrate materials, and fabrication techniques. The applications of these biosensors are then highlighted in detecting a variety of biochemical markers, such as small molecules, hormones, drugs, and macromolecules, in biofluids including interstitial fluid, sweat, wound exudate, saliva, and tears. Additionally, the review also covers recent advances in wearable electrochemical biosensing platforms, such as multi-sensory integration, closed-loop control, and power supply. Furthermore, the challenges associated with critical issues are discussed, such as biocompatibility, biofouling, and sensor degradation, and the opportunities in materials science, nanotechnology, and artificial intelligence to overcome these limitations.

Continuous Glucose Monitoring: A Transformative Approach to the Detection of Prediabetes

Prediabetes, as an intermediary stage between normal glucose homeostasis and overt diabetes, affects an estimated 720 million individuals worldwide, highlighting the urgent need for proactive intervention strategies. Continuous glucose monitoring (CGM) emerges as a transformative tool, offering unprecedented insights into glycemic dynamics and facilitating tailored therapeutic interventions. This perspective scores the clinical significance of even slightly elevated fasting blood glucose levels and the critical role of early intervention. CGM technology provides real-time, continuous data on glucose concentrations, surpassing the constraints of conventional monitoring methods. Both retrospectively analyzed and real-time CGM systems offer valuable tools for glycemic management, each with unique strengths. The integration of CGM into routine care can detect early indicators of type 2 diabetes, inform the development of personalized intervention strategies, and foster patient engagement and empowerment. Despite challenges such as cost and the need for effective utilization through training and education, CGM's potential to revolutionize prediabetes management is evident. Future research should focus on refining CGM algorithms, exploring personalized intervention strategies, and leveraging wearable technology and artificial intelligence advancements to optimize glycemic control and patient well-being.

Dual-Function Wearable Hydrogel Optical Fiber for Monitoring Posture and Sweat pH

In recent years, wearable devices have been widely used for human health monitoring. Such monitoring predominantly relies on the principles of optics and electronics. However, electronic detection is susceptible to electromagnetic interference, and traditional optical fiber detection is limited in functionality and unable to simultaneously detect both physical and chemical signals. Hence, a wearable, embedded asymmetric color-blocked optical fiber sensor based on a hydrogel has been developed. Its sensing principle is grounded in the total internal reflection within the optical fiber. The method for posture sensing involves changes in the light path due to fiber bending with color blocks providing wavelength-selective modulation by absorption changes. Sweat pH sensing is facilitated by variations in fluorescence intensity triggered by sweat-induced conformational changes in Rhodamine B. With just one fiber, it achieves both physical and chemical signal detection. Fabricated using a molding technique, this fiber boasts excellent biocompatibility and can accurately discern single and multiple bending points, with a recognition range of 0-90° for a single segment, a detection limit of 0.02 mm-1 and a sweat pH sensing linear regression R2 of 0.993, alongside great light propagation properties (-0.6 dB·cm-1). With its extensive capabilities, it holds promise for applications in medical monitoring.