An Anisotropic Biomimetic Lemongrass Flexible Piezoelectric Actuator-Inhibitory Regression

At present,the existing piezoelectric stick-slip actuators have an inherent back-slip problem,which greatly limits the development and application of stick-slip actuators.In order to inhibit the regression phenomenon,a new bionic lemongrass stickslip actuator was prepared by using polymer PDMS to replicate natural biological surface.The surface microstructure of the grass was copied by PDMS,and the PDMS film was prepared.The rigid and flexible bionic friction pair was further prepared,and the flexible anisotropic PDMS stick slip actuator was developed.It was found that the anisotropic friction characteristics of the surface microstructure of the grass inhibited the anti-sliding motion,and the elastic potential energy of the PDMS film improved the output characteristics of the driver.By adjusting the input voltage to control the contact between the drive foot and the rotor,the rigid and flexible hybrid drive can be realized and the backsliding phenomenon can be suppressed.The actuator is compact,lightweight and can achieve high speed and high resolution output without preloading force,which has important application value in the field of fast and accurate positioning with load limitation.

A Bionic Study on the Anti-erosion Mechanism of Laudakia stoliczkana:Experimental and Numerical Aspects

The scales of body surface of Laudakia stoliczkana have the morphology of convex hulls,which are arranged in groove structure in macroscopic scale.Its body surface skin is mainly composed of the"soft"layer of keratin and the"hard"layer of the cuticle covering on the"soft"layer.The coupling effect of the scale morphology and skin's structure gives Laudakia stoliczkana the excellent ability to resist the sand erosion in desert environment.Inspired by the convex surface morphology and the composite structure of the"soft"and"hard"layers of the skin of Laudakia stoliczkana^the coupling bionic samples are febricated and the erosion resistance performance is tested.The test results show that the coupling bionic samples have good erosion resistance perfbimance and the samples with spherical convex hull exhibit the best erosion resistance performance.Moreover,based on the theory of stress wave propagation in solid the numerical simula tions of particles impacting to the coupling bionic samples and bionic layered structure are done respectively and the anti-erosion me chanism of the bionic layered structure is analyzed.The simulation results are consistent with the experimental results,which show that the coupling bionic samples can effectively reduce the amplitude of the incident stress wave,and thus can prevent the failure of samples.

Outcomes of surgery for epiblepharon accompanied with lower eyelid retraction secondary to buphthalmos in children

Importance:In cases of epiblepharon with lower eyelid retraction secondary to glaucoma,correcting epiblepharon alone is ineffective.Combined surgery should be performed to obtain satisfactory outcomes.Objective:To investigate outcomes after surgery to correct epiblepharon with lower eyelid retraction secondary to buphthalmos in children.Methods:A retrospective analysis of six eyes in four patients was performed included lower lid retractor recession combined with marginal rotation with tarsal fixation.The margin reflex distance-2,lagophthalmus,resolution of clinical symptoms,and complications were assessed during 6 to 12 months of follow-up.Results:In all cases,epiblepharon and lagophthalmus were corrected,symptoms of photophobia and epiphora were relieved,and the corneal epithelium was repaired.The margin reflex distance-2 decreased and remained normal during the follow-up period,but slightly regressed within 6 months postoperatively.Interpretation:Epiblepharon caused by buphthalmos in children is often associated with lower eyelid retraction.Lower lid retractor recession combined with marginal rotation with tarsal fixation fundamentally solves the problems of high eyelid tension,lower eyelid retraction,and epiblepharon and reduces the recurrence rate.