Silicon micro pyramidal syringe array for electrospinning spiral shape single fiber

Abstract

In this study, a new method is presented to fabricate spiral shape single fiber. The micro-needle array (40 μ m hole diameter, 80 μ m outer diameter, and 100 μ m height) is utilized instead of the needle to reduce the diameter of fibers which are electrospun from 23Wt% PVP concentration. In order to have fine and bead-free fibers, the structural parameters of the micro-needle array and space which close microneedles act as an individual one are simulated. The Wet and Dry Etching techniques are used for fabrication of micro-needles. The experimental setup consists of the stepper motor and micrometer head as the pump, distance controller, and voltage generator. The single fiber can be electrospun by applying 1–3 kV bias within 1 mm gap between micro-needle and collector. Using nonconductive collector causes the formation of spiral type single fiber instead of agglomerate fiber. Elastic and expulsion forces in charged fibers seem to be the main reasons of fiber separation and spiral shape formation. The spiral shape fiber is made without traditional lithography techniques like direct patterning or contact exposure which are more expensive and time-consuming. The alteration in the fiber pattern can be seen by changing the applied voltage and spinneret, microneedle and needle. After various experiments, spirality pattern electrospun by microneedle with 10–15 μ m and 15–35 μ m distribution area of first and second circles and 500–570 nm and 570–660 nm diameter of first and second circles is gained as the structure with minimum distribution area and fiber width. This structure is created when the applied voltage and distance between microneedle and collector are 1kV and 1 mm.

Keywords

• micro/nano fiber
• near field electrospinning
• mems strucures
• microneedle array
• dry etch