The Preparation Of Thermoresponsive Slippery Surface Based On Femotosecond Laser Towards Droplet Dynamic Manipulation

Femtosecond laser micro/nano machining technology is widely used in the field of biomimetic materials with special wettability because of its significant merits of high processing resolution and true 3D processing.As a new type of functional material in recent years,stimulus-responsive material is drawn into the design of bionic superwetting interfaces,which can realize rapid and accurate regulation of interface wettability under external stimulation.In this paper,polydimethylsiloxane（PDMS）was functioned synthetically by combining femtosecond laser and responsive materials to form the bionic slippery/anisotropic interface for droplet dynamic manipulation,and the microdroplet manipulation performance were optimized by tuning femtosecond laser processing parameters and responsive material composition parameters to realize the potential applications in lab-on-a-chip,microfluidics and biomedical engineering.The main contents of this paper include the following two parts:（1）We have fabricated a kind of Nepenthes-inspired photoresponsive slippery lubricant-infused porous surface（SLIPS）by taking advantages of femtosecond laser orthogonal line scanning and photothermal Fe₃O₄ nanoparticles,which can bring about the dynamic control of droplet movement state and sliding routes upon adjusting a unilateral NIR-trigger position.In addition,we have quantitatively analyzed the relationship among Fe₃O₄-doped-content,droplet volume,lubricant rheological performance,liquid species and induced wettability gradient force(F_wet-grad),sliding velocity involved in the NIR-induced process.Based on the intelligent liquid manipulator formed by the optimized parameters with respect to droplet’s hydrokinetics,we can remotely drive functional droplets to exhibit the on-off state of an electrical-circuit,droplets fusion of microreactor and targeted drug delivery for the culture/inhibition of biological cells.（2）Through the utilization of femtosecond laser line-scanning and conductive silver nanowire heater,we have manufactured an electric-responsive paraffin-infused anisotropic slippery surfaces（ER-PIASS）with the comprehensive morphology of Nepenthes and rice leaves.Owing to fast phase-regulation of top paraffin wax of Joule-heated ER-PIASS,the reversible transformation between anisotropic sliding/pinning state for various conductive/non-conductive droplets could be achieved by remotely loading and discharging electric-stimuli.Based on the quantitative analysis of femtosecond laser processing parameters,hot spin coating parameters and working voltage,the interface anisotropy performance optimization is thus harvested.Through adjusting the hybrid paraffin recipe,the intelligent ultralow-voltage-driven manipulator can be utilized to reveal the 2D/3D microfluidics and the directional coalescence of cell culture/inhibitor media and yeast droplets for the cell-growth control.