Nonlinearly Frequency-Adaptive, Self-Powered, Proton-Driven Somatosensor Inspired by a Human Mechanoreceptor

Biomimetic Wearable Sensors: Emerging Combination of Intelligence and Electronics

Owing to the advancement of interdisciplinary concepts, for example, wearable electronics, bioelectronics, and intelligent sensing, during the microelectronics industrial revolution, nowadays, extensively mature wearable sensing devices have become new favorites in the noninvasive human healthcare industry. The combination of wearable sensing devices with bionics is driving frontier developments in various fields, such as personalized medical monitoring and flexible electronics, due to the superior biocompatibilities and diverse sensing mechanisms. It is noticed that the integration of desired functions into wearable device materials can be realized by grafting biomimetic intelligence. Therefore, herein, the mechanism by which biomimetic materials satisfy and further enhance system functionality is reviewed. Next, wearable artificial sensory systems that integrate biomimetic sensing into portable sensing devices are introduced, which have received significant attention from the industry owing to their novel sensing approaches and portabilities. To address the limitations encountered by important signal and data units in biomimetic wearable sensing systems, two paths forward are identified and current challenges and opportunities are presented in this field. In summary, this review provides a further comprehensive understanding of the development of biomimetic wearable sensing devices from both breadth and depth perspectives, offering valuable guidance for future research and application expansion of these devices.

The Importance of the Diaphragm in Neuromotor Function in the Patient with Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a constant and chronic narrowing of the respiratory airways, with numerous associated symptoms, not always related to the pathological adaptation of the lungs. Statistical projections show that COPD could become the third leading cause of death globally by 2030, with a significant increase in deaths by 2060. Skeletal muscle dysfunction, including the diaphragm, is one of the causes linked to the increase in mortality and hospitalization. Little emphasis is given by the scientific literature to the importance of the diaphragm towards functional neuromotor pathological expressions. The article reviews the adaptation of the skeletal muscles, with greater attention to the adaptations of the diaphragm, thereby highlighting the non-physiological variations that the main respiratory muscle undergoes and the neuromotor impairment found in COPD. The text could be an important reflection from a clinical and rehabilitation point of view, to direct greater attention to the function and adaptation of the diaphragm muscle.

Emerging Development of Auto-Charging Sensors for Respiration Monitoring

In recent years, the development of biomedical monitoring systems, including respiration monitoring systems, has been accelerated. Wearable and implantable medical devices are becoming increasingly important in the diagnosis and management of disease and illness. Respiration can be monitored using a variety of biosensors and systems. Auto-charged sensors have a number of advantages, including low cost, ease of preparation, design flexibility, and a wide range of applications. It is possible to use the auto-charged sensors to directly convert mechanical energy from the airflow into electricity. The ability to monitor and diagnose one's own health is a major goal of auto-charged sensors and systems. Respiratory disease model output signals have not been thoroughly investigated and clearly understood. As a result, figuring out their exact interrelationship is a difficult and important research question. This review summarized recent developments in auto-charged respiratory sensors and systems in terms of their device principle, output property, detecting index, and so on. Researchers with an interest in auto-charged sensors can use the information presented here to better understand the difficulties and opportunities that lie ahead.

A Wearable All-Gel Multimodal Cutaneous Sensor Enabling Simultaneous Single-Site Monitoring of Cardiac-Related Biophysical Signals

The human cutaneous sensory organ is a highly evolved biosensor that is efficient, sensitive, selective, and adaptable. Recently, with the development of various materials and structures inspired by sensory organs, artificial cutaneous sensors have been widely studied. In this study, the acquisition of biophysical signals is demonstrated at one point on the body using a wearable all-gel-integrated multimodal sensor composed of four element sensors, inspired by the slow/rapid adapting functions of the skin sensory receptors. The gel-type sensors ensure flexibility, compactness, portability, adherence, and integrity. The wearable all-gel multimodal sensor is easily attached to the wrist and simultaneously gathers blood pressure (BP), electrocardiogram (ECG), electromyogram (EMG), and mechanomyogram (MMG) signals related to cardiac and muscle health. Human activity causes muscle contraction, which affects blood flow; therefore, the relationship between the muscle and heart is crucial for screening and predicting heart health. Cardiac health is monitored by obtaining the two types of phase time differences (i.e., Δt_be : BP and ECG, Δt_em : ECG and MMG) generated during muscle movement. The suggested multimodal sensor has potential applicability in monitoring biophysical conditions and diagnosing cardiac-related health problems.

Recent progress of self-powered respiration monitoring systems

Wearable and implantable medical devices are playing more and more key roles in disease diagnosis and health management. Various biosensors and systems have been used for respiration monitoring. Among them, self-powered sensors have some special characteristics such as low-cost, easy preparation, highly designable, and diversified. The respiratory airflow can drive the self-powered sensors directly to convert mechanical energy of the airflow into electricity. One of the major goals of the self-powered sensors and systems is realizing health monitoring and diagnosis. The relationship between the output signals and the models of respiratory diseases has not been studied deeply and clearly. Therefore, how to find an accurate relationship between them is a challenging and significant research topic. This review summarized the recent progress of the self-powered respiratory sensors and systems from aspects of device principle, output property, detecting index and so on. The challenges and perspectives have also been discussed for reference to the researchers who are interested in the field of self-powered sensors.

Self-Powered, Stretchable, and Wearable Ion Gel Mechanoreceptor Sensors

Mechanoreceptors in human skin are important and efficient cutaneous sensors that are highly sensitive, selective, and adaptive to the environment. Among these, Merkel disk (MD) and cilia are capable of sensing an external mechanical force through a receptor with a sharp pillar-like structure at its end. Then, the signal of the action potential is generated by pumping Na⁺ ions through ion channels. In this study, a self-powered, stretchable, and wearable gel mechanoreceptor sensor is developed inspired by the structural features of the MD and cilia with sharp tips and the signaling characteristics of mechanoreceptor ion migration. Poly(vinylidene fluoride-co-trifluoroethylene) gel is used to implement a self-powered system, and polyvinylchloride-based elastic gel is utilized to detect sensing signals based on charge transfer and distribution. The surface of all gels is that of a conical structure to achieve high sensor sensitivity and conformal contact with a target surface. In addition, using the developed sensors, various biological signals related to pressure/strain occurring in the human body (e.g., blood pressure (BP), muscle movement, and motion) are acquired. Furthermore, the behavior of arterial BP was investigated during the contraction and relaxation of the muscles.