Fish Skin-Inspired Janus Hydrogel Coating for Drag Reduction

Comprehensive Summary,In nature,fishes have evolved functional skins with effective hydrodynamic performance and anti-fouling,facilitating predation and escaping from predators.Although a large number of fish scale-inspired structured surfaces have been explored,the incorporation of mucus on the structured surfaces has been largely ignored.Inspired by the skin of Osteichthyes fishes,a Janus hydrogel coating(JHC)is successfully prepared by a two-step UV light irradiation at room temperature.The bottom side of JHC(STH)achieves a shear adhesive strength of 103.3±17.5 kPa and can strongly adhere to a large variety of surfaces,including metals,ceramic and polymers.The top surface of JHC(SLH)replicates the structure of cycloid scales,while the nature of hydrogel mimics the mucus on fish skin.SLH possesses prominent mechanical,anti-swelling,anti-fouling and drag reduction properties.The design strategy for JHC has potential applications in numerous fields,like,pipeline transportation,bioengineering,and shipping industry.

Multilevel Micro Structures of the Clam Make the Sealing Even Tighter

Excellent fluid sealing performance is crucial to ensuring the safety of important equipment,especially in aerospace field,such as space capsule and fuel chamber.The frequently opening and closing of the sealing devices is particularly important.Driven by this background,clams(Mactra chinensis)which can open and close their double shells with superior sealing performance,are studied in this work.Here,we show that the clam’s sealing ability is the result of its unique multilevel intermeshing microstructures,including hinge teeth and micro-blocks.These microstructures,which resemble gear teeth,engage with each other when the shell closes,forming a tight structure that prevents the infiltration of water from the outside.Furthermore,the presence of micron blocks prevents the penetration of finer liquids.The simulation results of the bionic end seal components show that the multilevel microstructure has a superior sealing effect.This research is expected to be applied to undersea vehicles that require frequent door opening and closing.

Pomelo Peel-Inspired 3D-Printed Porous Structure for Efficient Absorption of Compressive Strain Energy

The porous structure in pomelo peel is believed to be responsible for the protection of its fruit from damage during the free falling from a tree.The quantitative understanding of the relationship between the deformation behavior and the porous structure could pave the way for the design of porous structures for efficient energy absorption.Here,a universal feature of pore distribution in pomelo peels along the radial direction is extracted from three varieties of pomelos,which shows strong correlation to the deformation behavior of the peels under compression.Guided by the porous design found in pomelo peels,porous polyether-ether-ketone(PEEK)cube is additively manufactured and possesses the highest ability to absorb energy during compression as compared to the non-pomelo-inspired geometries,which is further confirmed by the finite element simulation.The nature-optimized porous structure revealed here could guide the design of lightweight and high-energy-dissipating materials/devices.

A two-stage amplified PZT sensor for monitoring lung and heart sounds in discharged pneumonia patients

Assessment of lung and heart states is of critical importance for patients with pneumonia.In this study,we present a small-sized and ultrasensitive accelerometer for continuous monitoring of lung and heart sounds to evaluate the lung and heart states of patients.Based on two-stage amplification,which consists of an asymmetric gapped cantilever and a charge amplifier,our accelerometer exhibited an extremely high ratio of sensitivity to noise compared with conventional structures.Our sensor achieves a high sensitivity of 9.2V/g at frequencies less than 1000 Hz,making it suitable to use to monitor weak physiological signals,including heart and lung sounds.For the first time,lung injury,heart injury,and both lung and heart injuries in discharged pneumonia patients were revealed by our sensor device.Our sound sensor also successfully tracked the recovery course of the discharged pneumonia patients.Over time,the lung and heart states of the patients gradually improved after discharge.Our observations were in good agreement with clinical reports.Compared with conventional medical instruments,our sensor device provides rapid and highly sensitive detection of lung and heart sounds,which greatly helps in the evaluation of lung and heart states of pneumonia patients.This sensor provides a cost-effective alternative approach to the diagnosis and prognosis of pneumonia and has the potential for clinical and home-use health monitoring.

3D printing of bioinspired compartmentalized capsular structure for controlled drug release

Drug delivery with customized combinations of drugs,controllable drug dosage,and on-demand release kinetics is critical for personalized medicine.In this study,inspired by successive opening of layered structures and compartmentalized structures in plants,we designed a multiple compartmentalized capsular structure for controlled drug delivery.The structure was designed as a series of compartments,defined by the gradient thickness of their external walls and internal divisions.Based on the careful choice and optimization of bioinks composed of gelatin,starch,and alginate,the capsular structures were successfully manufactured by fused deposition modeling three-dimensional(3 D)printing.The capsules showed fusion and firm contact between printed layers,forming complete structures without significant defects on the external walls and internal joints.Internal cavities with different volumes were achieved for different drug loading as designed.In vitro swelling demonstrated a successive dissolving and opening of external walls of different capsule compartments,allowing successive drug pulses from the capsules,resulting in the sustained release for about 410 min.The drug release was significantly prolonged compared to a single burst release from a traditional capsular design.The bioinspired design and manufacture of multiple compartmentalized capsules enable customized drug release in a controllable fashion with combinations of different drugs,drug doses,and release kinetics,and have potential for use in personalized medicine.

Bioinspired super-hydrophilic zwitterionic polymer armor combats thrombosis and infection of vascular catheters

Thrombosis and infection are two major complications associated with central venous catheters(CVCs),which significantly contribute to morbidity and mortality.Antifouling coating strategies currently represent an efficient approach for addressing such complications.However,existing antifouling coatings have limitations in terms of both duration and effectiveness.Herein,we propose a durable zwitterionic polymer armor for catheters.This armor is realized by pre-coating with a robust phenol-polyamine film inspired by insect sclerotization,followed by grafting of poly-2-methacryloyloxyethyl phosphorylcholine(pMPC)via in-situ radical polymerization.The resulting pMPC coating armor exhibits super-hydrophilicity,thereby forming a highly hydrated shell that effectively prevents bacterial adhesion and inhibits the adsorption and activation of fibrinogen and platelets in vitro.In practical applications,the armored catheters significantly reduced inflammation and prevented biofilm formation in a rat subcutaneous infection model,as well as inhibited thrombus formation in a rabbit jugular vein model.Overall,our robust zwitterionic polymer coating presents a promising solution for reducing infections and thrombosis associated with vascular catheters.