Flexible wearable sensors:An emerging platform for monitoring of bacterial infection in skin wounds

Persistent inflammatory responses often occur when bacteria and other microorganisms frequently invade and colonize open wounds and eventually result in the formation of chronic wounds.Therefore,achieving real-time detection of invasive bacteria accurately and promptly is essential for efficient wound management and accelerat-ing the healing process.Recently,flexible wearable sensors have garnered significant attention,especially those designed for monitoring real-time biophysical or biochemical signals in wound sites in a minimally invasive manner.They provide more precise and continuous monitoring data,making them as emerging tools for clinical diagnostics.In this review,we first discuss the species and community distribution of different types of bacteria in chronic wounds.Next,we introduce currently developed techniques for detecting bacteria at wound sites.Fol-lowing that,we discuss the recent progress and unresolved issues of various flexible wearable sensors in detecting bacteria at wound sites.We believe that this review can provide meaningful guidance for the development of flexible wearable sensors for bacteria detection.

Smart Gas Sensors:Recent Developments and Future Prospective

Gas sensor is an indispensable part of modern society withwide applications in environmental monitoring,healthcare,food industry,public safety,etc.With the development of sensor technology,wireless communication,smart monitoring terminal,cloud storage/computing technology,and artificial intelligence,smart gas sensors represent the future of gassensing due to their merits of real-time multifunctional monitoring,earlywarning function,and intelligent and automated feature.Various electronicand optoelectronic gas sensors have been developed for high-performancesmart gas analysis.With the development of smart terminals and the maturityof integrated technology,flexible and wearable gas sensors play an increasingrole in gas analysis.This review highlights recent advances of smart gassensors in diverse applications.The structural components and fundamentalprinciples of electronic and optoelectronic gas sensors are described,andflexible and wearable gas sensor devices are highlighted.Moreover,sensorarray with artificial intelligence algorithms and smart gas sensors in“Internet of Things”paradigm are introduced.Finally,the challengesand perspectives of smart gas sensors are discussed regarding the future need of gas sensors for smart city and healthy living.

Recent progress of flexible and wearable strain sensors for human-motion monitoring

With the rapid development of human artificial intelligence and the inevitably expanding markets, the past two decades have witnessed an urgent demand for the flexible and wearable devices, especially the flexible strain sensors. Flexible strain sensors, incorporated the merits of stretchability, high sensitivity and skin-mountable,are emerging as an extremely charming domain in virtue of their promising applications in artificial intelligent realms, human-machine systems and health-care devices. In this review, we concentrate on the transduction mechanisms, building blocks of flexible physical sensors, subsequently property optimization in terms of device structures and sensing materials in the direction of practical applications. Perspectives on the existing challenges are also highlighted in the end.

Flexible Piezoelectric Sensor Based on Two‑Dimensional Topological Network of PVDF/DA Composite Nanofiber Membrane

Owing to the robust scalability,ease of control and substantial industrial applications,the utilization of electrospinning technology to produce piezoelectric nanofiber materials demonstrates a significant potential in the development of wearable products including flexible wearable sensors.However,it is unfortunate that the attainment of high-performance piezoelec-tric materials through this method remains a challenging task.Herein,a high-performance composite nanofiber membrane with a coherent and uniformly dispersed two-dimensional network topology composed of polyvinylidene fluoride(PVDF)/dopamine(DA)nanofiber membranes and ultrafine PVDF/DA nanofibers was successfully fabricated by the electrospinning technique.Based on the evidence obtained from simulations,experimental and theoretical results,it was confirmed that the unique structure of the nanofiber membrane significantly enhances the piezoelectric performance.The present PVDF/DA composite nanofibers demonstrated a remarkable piezoelectric performance such as a wide response range(1.5–40 N),high sensitivity to weak forces(0–4 N,7.29 V N^(-1)),and outstanding operational durability.Furthermore,the potential application of the present PVDF/DA membrane as a flexible wearable sensor for monitoring human motion and subtle physiological signals has also been validated.This work not only introduces a novel strategy for the application of electrospun nanofibers in sensors but also provides new insights into high-performance piezoelectric materials.