Nanofiber self-consistent additive manufacturing process for 3D microfluidics

3D microfluidic devices have emerged as powerful platforms for analytical chemistry,biomedical sensors,and microscale fluid manipulation.3D printing technology,owing to its structural fabrication flexibility,has drawn extensive attention in the field of 3D microfluidics fabrication.However,the collapse of suspended structures and residues of sacrificial materials greatly restrict the application of this technology,especially for extremely narrow channel fabrication.In this paper,a 3D printing strategy named nanofiber self-consistent additive manufacturing(NSCAM)is proposed for integrated 3D microfluidic chip fabrication with porous nanofibers as supporting structures,which avoids the sacrificial layer release process.In the NSCAM process,electrospinning and electrohydrodynamic jet(E-jet)writing are alternately employed.The porous polyimide nanofiber mats formed by electrospinning are ingeniously applied as both supporting structures for the suspended layer and percolating media for liquid flow,while the polydimethylsiloxane E-jet writing ink printed on the nanofiber mats(named construction fluid in this paper)controllably permeates through the porous mats.After curing,the resultant construction fluid–nanofiber composites are formed as 3D channel walls.As a proof of concept,a microfluidic pressure-gain valve,which contains typical features of narrow channels and movable membranes,was fabricated,and the printed valve was totally closed under a control pressure of 45 kPa with a fast dynamic response of 52.6 ms,indicating the feasibility of NSCAM.Therefore,we believe NSCAM is a promising technique for manufacturing microdevices that include movable membrane cavities,pillar cavities,and porous scaffolds,showing broad applications in 3D microfluidics,soft robot drivers or sensors,and organ-on-a-chip systems.

A microfluidically controlled concave–convex membrane lens using an addressing operation system

Electrical control toolkits for microlens arrays are available to some extent,but for applications in environments with strong electromagnetic fields,radiation,or deep water,non-electrical actuation and control strategies are more appropriate.An integrated digital microfluidic zoom actuating unit with a logic addressing unit for a built-in membrane lens array,e.g.,a flexible bionic compound eye,is developed and studied in this article.A concave–convex membrane fluidic microvalve,which is the component element of the logic gate,actuator,and microlens,is proposed to replace the traditional solenoid valve.The functions of pressure regulation and decoding can be obtained by incorporating microvalves into fluidic networks according to equivalent circuit designs.The zoom actuating unit contains a pressure regulator to adjust the focal length of lenses with three levels,and the logic addressing unit contains a decoder to choose a typical lens from a hexagonal lens array.The microfluidic chip control system is connected flexibly to the actuating part,a membrane lens array.It is shown from a simulation and experimental demonstration that the designed and fabricated system,which is composed of a whole microfluidic zoom unit,addressing technology,and a microlens array,works well.Because these components are constructed in the same fabrication process and operate with the same work media and driving source,the system can be made highly compatible and lightweight for applications such as human-machine interfaces and soft robots.