Construction,Modification And Application Of Flexible Stress Sensors Based On Two-dimensional MoS₂

The exceptional flexibility,sensitivity,and ease of integration of flexible pressure sensors have captured considerable interest in the domains of wearable medical monitoring and human-computer interaction.Despite the advancements that have been made in pressure sensor technology,there is still a critical need for sensors that exhibit superior sensitivity,rapid response rates,sustained mechanical durability,adaptable structures,and can be manufactured on a large scale.The objective of this study is to develop active materials for flexible pressure sensors by utilizing layered transition metal sulfide molybdenum disulfide（MoS₂）semiconductor material,combined with other organic or inorganic materials possessing excellent conductivity.Moreover,the primary aim of this investigation is to utilize scalable production technology to create an assortment of wearable pressure sensors and arrays that have a multitude of applications,including monitoring human movement and physiological indicators,recognizing targeted objects through grasping,responding to Morse code,and determining the spatial pressure distribution of objects.The research encompasses the following contents:（1）The construction of capacitive and resistive dual-mechanism flexible pressure sensors are achieved through the synergistic effect of MoS₂nanoflowers and poly（3,4-ethylenedioxythiophene）:poly（styrene sulfonate）（PEDOT:PSS）.The solution processing technology enables the uniform composite inks of MoS₂and PEDOT:PSS with compatible physical properties,which can be adapted to the scalable preparation process of flexible sensors.The microstructure of the electrode support layer polydimethylsiloxane（PDMS）at the micron scale and the composite sensing material at the nanoscale jointly improve the sensitivity and response capability of the devices.The resulting capacitive and resistive sensors exhibit sensitivities of 0.372 k Pa^-1and 0.12 k Pa^-1,respectively,and response times of approximately 100 ms.In addition,it is worth noting that the dual-mechanism pressure sensors exhibit remarkable mechanical resilience,withstanding no less than 10,000 cycles of loading and unloading.This can be attributed to the superior adhesion between the PEDOT:PSS layer that encloses the MoS₂nanoflowers and the PDMS substrate that has undergone hydrophilic treatment.The sensors possess the ability to detect human joint movement and faint physiological signals,as well as identify grasping target objects.Notably,the recognition accuracy rate for ten distinct objects is an impressive 98%,which serves as a testament to the widespread applicability of the MoS₂/PEDOT:PSS composite electrode in high-performance dual-mechanism flexible pressure sensors.（2）A scalable approach to constructing flexible piezoresistive sensors utilizing MXene@MoS₂hierarchical nanostructures is developed.The technique involves combing the MXene@MoS₂material with a three-dimensional porous cellulose fabric to create a sensing layer that can be adjusted in size.This layer can then be assembled with inkjet-printed interdigitated electrodes to produce flexible piezoresistive sensors and arrays.The hierarchical nanostructure provides ample electron transport paths during loading,while the addition of semiconductor MoS₂effectively prevents self-stacking of MXene and enhances the initial resistance of the sensor.This leads to increased device sensitivity(0.395 k Pa^-1),fast response characteristics（～36 ms）,and superior mechanical stability and durability（at least～10,000cycles）.The sensors showcase swift reaction to Morse code,have the ability to detect human joint motion,and can distinguish between different states of human pulse signals.Additionally,the integrated sensor array not only reflects the magnitude and distribution of applied pressure,but also provides the robotic fingers with high-resolution sensing capabilities.As a result of employing the structural layout of semiconductor/conductor composite multi-dimensional materials,coupled with economical and scalable production methods,this investigation has produced a variety of flexible pressure sensors that display exceptional sensitivity,swift response times,and superior mechanical robustness.These discoveries provide significant perspectives for the progression and improvement of flexible pressure sensor technology,as well as for product innovation and advancement.