Preparation And Performance Of Flexible And Multifunctional Sensing Materials Based On Ionic Liquids

As the great development in human-machine interfaces,electronic skins and wearable electronic devices,flexible sensing materials have attracted great attentions this year.However,traditional flexible sensing materials are normally composed of rigid conductive materials such as metal nanoparticles or nanowires,carbonaceous nanoparticles and stretchable polymer,which exhibit poor flexibility,single sensing function,low transparency,and poor sensitivity.In this dissertation,we used IL as conductive filler to incorporate with stretchable polydimethylsiloxane(PDMS)and thermoplastic polyurethane(TPU)to prepare flexible multifunctional sensing materials,which possessed high stretchability,outstanding transparency,high sensitivity in temperature sensing and strain sensing.Specific research contents and the results are summarized as follows:1.Preparation and performance of flexible and transparent PDMS/IL temperature sensing and strain sensing materials: Using PDMS as the elastic substrate to encapsulate the non-volatile,chemically stable IL into the micro-channel,we fabricated a stretchable and transparent flexible multifunctional sensor.This sensor exhibits various merits,including high flexibility,transparency,sensitivity to strain and temperature,and outstanding monotonicity,linearity,and resolution of the outputted signals,which can be the promising candidate of stretchable strain sensor and temperature sensor in various fields.More interestingly,a feature of this sensor is that the resistance is only slightly increased under large tensile strain,which makes it possible for serving as the stretchable conductor simultaneously.This work proposes a new strategy that allows the creation of multifunctional sensor with high transparency,high sensitivity,and excellent linearity of the signal.2.Electrospinning TPU@IL fibrous film and its application in temperature sensor and strain sensor: A simple route is provided to design multifunctional sensors with high sensing performances for strain and temperature,which combines the electrospun technique and ultrasonication anchoring technique.Specifically,fibrous thermoplastic polyurethane(TPU)film is fabricated by electrospun technique at first,and then is saturated by ionic liquid(IL)to design the stretchable sensor associated by the ultrasound treatment.Attributed to the fast response and reconstruction of conductive pathways of ionic liquid under the stretching-releasing process,the fibrous TPU/IL film can designed into strain sensor,which exhibits various merits,including fast response time of 67 ms,ultra-low detection limit(0.1%),ultra-wide sensing range(0.1%to 400%)and excellent durability for long-term usage.In addition,it is noteworthy that fibrous TPU/IL film-based sensor has great advantages in temperature sensing,which possesses a lowest temperature accuracy of0.5 °C.The work provides a novel route for manufacting stretchable temperature sensor and strain sensor,which may accelerate the development of the emerging fields of wearable electronics and electrical skins.3.Preparation and performance of TPU/IL ionogels-based multifunctional sensors: Herein,we fabricate flexible and transparent(94.3%)ionogels by facilely mixing IL and TPU in solution,which can be used as skin-like sensors.The prepared TPU@IL ionogel-based sensor exhibits wide strain range(0.1-500%)and fast response(96 ms)to strain stimulus.Attributed to the temperature-dependent conductivity and low freezing point of IL,the ionogels can be served as stretchable temperature sensor with wide operating temperature window(-40-100 °C)and high detecting accuracy(0.1 °C).Moreover,the ionogel-based sensor exhibits excellent antibacterial activity and biocompatibility,which can be used to design full-featured skin-like sensors.