Adhesion strength of tetrahydrofuran hydrates is dictated by substrate stiffness

Understanding the hydrate adhesion is important to tackling hydrate accretion in petro-pipelines.Herein,the relationship between the Tetrahydrofuran(THF)hydrate adhesion strength(AS)and surface stiffness on elastic coatings is systemically examined by experimental shear force measurements and theoretical methods.The mechanical factor-elastic modulus of the coatings greatly dictates the hydrate AS,which is explained by the adhesion mechanics theory,beyond the usual factors such as wettability and structural roughness.Moreover,the hydrate AS increases with reducing the thickness of the elastic coatings,resulted from the decrease of the apparent surface elastic modulus.The effect of critical thickness for the elastic materials with variable elastic modulus on the hydrate AS is also revealed.This study provides deep perspectives on the regulation of the hydrate AS by the elastic modulus of elastic materials,which is of significance to design anti-hydrate surfaces for mitigation of hydrate accretion in petro-pipelines.

Electric-driven flexible-roller nanoimprint lithography on the stress-sensitive warped wafer

Surface nanopatterning of semiconductor optoelectronic devices is a powerful way to improve their quality and performance.However,photoelectric devices’inherent stress sensitivity and inevitable warpage pose a huge challenge on fabricating nanostructures large-scale.Electric-driven flexible-roller nanoimprint lithography for nanopatterning the optoelectronic wafer is proposed in this study.The flexible nanoimprint template twining around a roller is continuously released and recovered,controlled by the roller’s simple motion.The electric field applied to the template and substrate provides the driving force.The contact line of the template and the substrate gradually moves with the roller to enable scanning and adapting to the entire warped substrate,under the electric field.In addition,the driving force generated from electric field is applied to the surface of substrate,so that the substrate is free from external pressure.Furthermore,liquid resist completely fills in microcavities on the template by powerful electric field force,to ensure the fidelity of the nanostructures.The proposed nanoimprint technology is validated on the prototype.Finally,nano-grating structures are fabricated on a gallium nitride light-emitting diode chip adopting the solution,achieving polarization of the light source.

Discretely-supported nanoimprint lithography for patterning the high-spatial-frequency stepped surface

Non-planar morphology is a common feature of devices applied in various physical fields,such as light or fluid,which pose a great challenge for surface nano-patterning to improve their performance.The present study proposes a discretely-supported nanoimprint.lithography(NIL)technique to fabricate nanostructures on the extremely non-planar surface,namely high-spatial-frequency stepped surface.The designed discretely imprinting template implanted a discretely-supported intermediate buffer layer made of sparse pillars arrays.This allowed the simultaneous generation of air-cushion-like buffer and reliable support to the thin structured layer in the template.The resulting low bending stiffness and distributed concentrated load of the template jointly overcome the contact difficulty with a stepped surface,and enable the template to encase the stepped protrusion as tight as possible.Based on the proposed discretely-supported NIL,nanostructures were fabricated on the luminous interface of light emitting diodes chips that covered with micrometer step electrodes pad.About 96%of the utilized indium tin oxide transparent current spreading layer surface on top of the light emitting diode(LED)chips was coated with nanoholes array,with an increase by more than 40%in the optical output power.The excellent ability of nanopatterning a non-planar substrate could potentially lead innovate design and development of high performance device based on discretely-supported NIL.

A flexible dual-function capacitive sensor enhanced by looppatterned fibrous electrode and doped dielectric pillars for spatial perception

The integrated perception capable of detecting and monitoring varieties of activities is one of the ultimate purposes of wearable electronics and intelligent robots.Limited by the space occupation,it lacks practical feasibility to stack multiple types of single sensors on each other.Herein,a high-sensitivity dual-function capacitive sensor with proximity sensing and pressure sensing is proposed.The fringing electric field can be confined in the proximity-sensitive area by fibrous loop-patterned electrode,leading to more stolen charges when object approaching and thus a high proximity sensitivity.The high-permittivity doped structured dielectric layer reduces the compressive stiffness and enhances the rate of compression-caused increase in the equivalent relative permittivity of the dielectric layer,resulting in a larger increase in capacitance and thus a high pressure sensitivity.The electrodes and dielectric layer together compose the capacitor and act as the sensor without taking up additional space.The decoupling of proximity-sensing and pressure-sensing modes can be achieved by decrease or increase in capacitance.Combined with array distribution and sequential scanning,the sensors can be used for detection of motion trajectory,contour recognition,pressure distribution.

Gecko-Inspired Slant Hierarchical Microstructure-Based Ultrasensitive Iontronic Pressure Sensor for Intelligent Interaction

Highly sensitive flexible pressure sensors play an important role to ensure the safety and friendliness during the human-robot interaction process.Microengineering the active layer has been shown to improve performance of pressure sensors.However,the current structural strategy almost relying on axial compression deformation suffers structural stifening,and together with the limited area growth efficiency of conformal interface,essentially limiting the maximum sensitivity.Here,inspired by the interface contact behavior of gecko's feet,we design a slant hierarchical microstructure to act as an electrode contacting with an ionic gel layer,fundamentally eliminating the pressure resistance and maximizing functional interface expansion to achieving ultrasensitive sensitivity.Such a structuring strategy dramatically improves the relative capacitance change both in the low-and high-pressure region,thereby boosting the sensitivity up to 36000kPa^(-1) and effective measurement range up to 30okPa.To verify the advantages of high sensitivity,the sensor is integrated with a soft magnetic robot to demonstrate a biomimetic Venus flytrap.The ability to perceive weak stimuli allows the sensor to be used as a sensory and feedback window,realizing the capture of small live insects and the transportation of fragile objects.