A dual-switching spin-crossover framework with redox regulation and guest response

A dual-switching spin crossover metal-organic framework(SCO-MOF)[Fe(TPB){Pt^(Ⅱ)(CN)_(4)}]·3iPrOH·4H_(2)O(TPB=1,2,4,5-tetra(pyridin-4-yl)benzene)is developed via the combination of redox-active framework and tunable guests.The reversible structural transformation between[Pt^(Ⅱ)(CN)_(4)]^(2-) and[Pt^(Ⅳ)Br_(2)(CN)_(4)]^(2-)moieties can be manipulated by redox post-synthetic modification(PSM),which results in the change of SCO behaviors from step-wise to one-step.The influences of the oxidative addition of bromides on the ligand field splitting of Fe side are further explored by density functional theory calculations.Besides,the modulation of hysteretic four-/three-step,one-step and four-step SCO behaviors can be achieved by tuning the composition of guest molecules.Therefore,the combination of electronic bistability,redox reaction and guest recognition in a homogeneous lattice provides a utility platform for designing multi-responsive molecule-based materials.

Polymeric foams for flexible and highly sensitive low-pressure capacitive sensors

Flexible low-pressure sensors(<10 kPa)are required in areas as diverse as blood-pressure monitoring,human–computer interactions,robotics,and object detection.For applications,it is essential that these sensors combine flexibility,high sensitivity,robustness,and low production costs.Previous works involve surface micro-patterning,electronic amplification(OFET),and hydrogels.However,these solutions are limited as they involve complex processes,large bias voltages,large energy consumption,or are sensitive to evaporation.Here,we report a major advance to solve the challenge of scalable,efficient and robust e-skin.We present an unconventional capacitive sensor based on composite foam materials filled with conductive carbon black particles.Owing to the elastic buckling of the foam pores,the sensitivity exceeds 35 kPa^(−1) for pressure<0.2 kPa.These performances are one order of magnitude higher than the ones previously reported.These materials are low-cost,easy to prepare,and display high capacitance values,which are easy to measure using low-cost electronics.These materials pave the road for the implementation of e-skin in commercialized applications.

Engineering polymer MEMS using combined microfluidic pervaporation and micro-molding

In view of the extensive increase of flexible devices and wearable electronics,the development of polymer microelectro-mechanical systems(MEMS)is becoming more and more important since their potential to meet the multiple needs for sensing applications in flexible electronics is now clearly established.Nevertheless,polymer micromachining for MEMS applications is not yet as mature as its silicon counterpart,and innovative microfabrication techniques are still expected.We show in the present work an emerging and versatile microfabrication method to produce arbitrary organic,spatially resolved multilayer micro-structures,starting from dilute inks,and with possibly a large choice of materials.This approach consists in extending classical microfluidic pervaporation combined with MIcro-Molding In Capillaries.To illustrate the potential of this technique,bilayer polymer double-clamped resonators with integrated piezoresistive readout have been fabricated,characterized,and applied to humidity sensing.The present work opens new opportunities for the conception and integration of polymers in MEMS.

Percolation of carbon nanomaterials for high-k polymer nanocomposites

High-k polymer composite materials are next-generation dielectrics that show amazing applications in diverse electrical and electronic devices. Establishing near-percolated network of conducting filler in an insulating polymer matrix is a promising approach to develop flexible high-k dielectrics. However, challenges still exist today on fine controlling the network morphology to achieve extremely high k values and low losses simultaneously. The relationship between the network morphology and the dielectric properties of polymer composites is raising a number of fundamental questions. Herein, recent progress towards high-k polymer composites based on carbon nanomaterials is reviewed. Particular attention is paid on the influence of the network morphology on the dielectric properties. Some perspectives that warrant further investigation in the future are also addressed.