Smart bioelectronic pacifier for real-time continuous monitoring of salivary electrolytes.

Monitoring electrolytes is critical for newborns and babies in the intensive care unit. However, the gold standard methods use a blood draw, which is painful and only offers discrete measures. Although salivary-based detection offers promise as an alternative, existing devices are ineffective for real-time, continuous monitoring of electrolytes due to their rigidity, bulky form factors, and lack of salivary accumulation. Here, we introduce a smart, wireless, bioelectronic pacifier for salivary electrolyte monitoring of neonates, which can detect real-time continuous sodium and potassium levels without a blood draw. The miniature system facilitates the seamless integration of the ultralight and low-profile device with a commercial pacifier without additional fixtures or structural modifications. The portable device includes ion-selective sensors, flexible circuits, and microfluidic channels, allowing simplified measurement protocols in non-invasive electrolyte monitoring. The flexible microfluidic channel enables continuous and efficient saliva collection from a mouth. By modifying the surface properties of the channels and the structure of the capillary reservoir, we achieve reliable pumping of the viscous medium for quick calibration and measurement. Embedded sensors in the system show good stability and sensitivity: 52 and 57 mV/decade for the sodium and potassium sensor, respectively. In vivo study with neonates in the intensive care unit captures the device's feasibility and performance in the natural saliva-based detection of the critical electrolytes without induced stimulation.

Advances in Soft and Dry Electrodes for Wearable Health Monitoring Devices.

Electrophysiology signals are crucial health status indicators as they are related to all human activities. Current demands for mobile healthcare have driven considerable interest in developing skin-mounted electrodes for health monitoring. Silver-Silver chloride-based (Ag-/AgCl) wet electrodes, commonly used in conventional clinical practice, provide excellent signal quality, but cannot monitor long-term signals due to gel evaporation and skin irritation. Therefore, the focus has shifted to developing dry electrodes that can operate without gels and extra adhesives. Compared to conventional wet electrodes, dry ones offer various advantages in terms of ease of use, long-term stability, and biocompatibility. This review outlines a systematic summary of the latest research on high-performance soft and dry electrodes. In addition, we summarize recent developments in soft materials, biocompatible materials, manufacturing methods, strategies to promote physical adhesion, methods for higher breathability, and their applications in wearable biomedical devices. Finally, we discuss the developmental challenges and advantages of various dry electrodes, while suggesting research directions for future studies.

Fully implantable batteryless soft platforms with printed nanomaterial-based arterial stiffness sensors for wireless continuous monitoring of restenosis in real time.

Atherosclerosis is a common cause of coronary artery disease and a significant factor in broader cardiovascular diseases, the leading cause of death. While implantation of a stent is a prevalent treatment of coronary artery disease, a frequent complication is restenosis, where the stented artery narrows and stiffens. Although early detection of restenosis can be achieved by continuous monitoring, no available device offers such capability without surgeries. Here, we report a fully implantable soft electronic system without batteries and circuits, which still enables continuous wireless monitoring of restenosis in real-time with a set of nanomembrane strain sensors in an electronic stent. The low-profile system requires minimal invasive implantation to deploy the sensors into a blood vessel through catheterization. The entirely printed, nanomaterial-based set of soft membrane strain sensors utilizes a sliding mechanism to offer enhanced sensitivity and detection of low strain while unobtrusively integrating with an inductive stent for passive wireless sensing. The performance of the soft sensor platform is demonstrated by wireless monitoring of restenosis in an artery model and an ex-vivo study in a coronary artery of ovine hearts. The capacitive sensor-based artery implantation system offers unique advantages in wireless, real-time monitoring of stent treatments and arterial health for cardiovascular disease.