Recent advances in microsystem approaches for mechanical characterization of soft biological tissues

Microsystem technologies for evaluating the mechanical properties of soft biological tissues offer various capabilities relevant to medical research and clinical diagnosis of pathophysiologic conditions.Recent progress includes(1)the development of tissue-compliant designs that provide minimally invasive interfaces to soft,dynamic biological surfaces and(2)improvements in options for assessments of elastic moduli at spatial scales from cellular resolution to macroscopic areas and across depths from superficial levels to deep geometries.This review summarizes a collection of these technologies,with an emphasis on operational principles,fabrication methods,device designs,integration schemes,and measurement features.The core content begins with a discussion of platforms ranging from penetrating filamentary probes and shape-conformal sheets to stretchable arrays of ultrasonic transducers.Subsequent sections examine different techniques based on planar microelectromechanical system(MEMS)approaches for biocompatible interfaces to targets that span scales from individual cells to organs.One highlighted example includes miniature electromechanical devices that allow depth profiling of soft tissue biomechanics across a wide range of thicknesses.The clinical utility of these technologies is in monitoring changes in tissue properties and in targeting/identifying diseased tissues with distinct variations in modulus.The results suggest future opportunities in engineered systems for biomechanical sensing,spanning a broad scope of applications with relevance to many aspects of health care and biology research.

Hierarchically nanostructured nitrogen-doped porous carbon multilayer confining Fe particles for high performance hydrogen evolution

Precise assembly of active component with sophisticated confinement in electrocatalyst are promising to increase the active site exposure for enhanced hydrogen evolution reaction(HER).Here,PCN-333 films with mesopores are firstly assembled on titanium carbide MXene with the assistance of atomic layer deposited oxide nanomembrane.With the whereafter pyrolysis process,the composite is converted to Ndoped porous carbon multi-layer containing Fe nanoparticles.The strong confinement of Fe active particle in carbon as well as great contact between metal and carbon effectively enhance active site exposure.Furthermore,this multi-layer porous structure provides high specific surface area and plentiful mesopores for electrolyte penetration.Due to the structural advantage,the composite can be well functioned in both acid and alkaline electrolytes with excellent HER performance,e.g.,low overpotential/Tafel slope.The present work may have great potential in developing high efficiency transition-metal based electrocatalysts.

Foldable-circuit-enabled miniaturized multifunctional sensor for smart digital dust

Smart dust,which refers to miniaturized,multifunctional sensor motes,would open up data acquisition opportunities for Internet of Things(IoT)and Environmental protection applications.However,critical obstacles remain challenging in the integration of high-density sensors,further miniaturization of device platforms,and reduction of cost.Here,we demonstrate the concept of smart digital dust to address these problems,the results of which combine the benefit of(i)maturity of complementary metal-oxide semiconductor(CMOS)processing approaches and(ii)unique form factors of emerging flex-ible electronics.As a prototype for smart digital dust,we present a millimeter-scale multifunctional optoelectronic sensor platform con-sisting of high-performance optoelectronic sensor cores and commer-cially available integrated-circuit components.The smart material-assisted optoelectronic sensing mechanism enables real-time,high-sensitivity hydrogen,temperature,and relative humidity(RH)sens-ing based on a single chip with ultralow power consumption.Such a microsystem presented here introduces a viable solution to the multi-functional sensing need of IoT and could serve as a building block for the rapidly evolving future framework of smart dust.