Fibrillar Substrate

Introduction

In this project, I created an acoustically actuatable fibrillar substrate (AAFS) and created noticeable deflection in the fibrillar posts during actuation. The overarching goal is to develop the AAFS into a culture dish that maintains embryos in an environment mimicking the oviductal environment. This environment should increase the rate of successful births and decrease the frequency of epigenetic disorders compared to current in vitro fertilization procedures. However, the scope of this project only covers the fabrication of a substrate and generating noticeable movement of the posts during actuation. Movement of the posts is supposed to emulate cilia movement that would apply shear stresses to the embryo in the oviduct.

Fabrication

To make the posts, polydimethylsiloxane (PDMS) mixture was poured onto silicon wafers with desired post size. The PDMS was then cured in the oven and the silicon wafers were peeled off, leaving negative molds. New PDMS mixture was spread onto the negative molds and then the negative molds were stamped onto coverslips. The molds were cured in the oven and then peeled off from the coverslips to leave fibrillar substrates on the coverslips.

A 3-D printed petri dish that fits tightly into the microscope stage was fabricated. The substrate cover glasses and a transducer were epoxied onto this petri dish. The transducer was activated using a waveform generator and a power amplifier.

Analysis

Acoustically actuated pillar movement videos were taken from the top view using a high-speed camera and analyzed in MATLAB. Images from the videos were converted to black and white based on a set darkness value to determine whether a pixel would become black or white. Then, based on connections of the white pixels, objects (the tops of the pillars) were identified and boxed. Identifying the posts in MATLAB allows for deeper analysis of the images such as counting the number of posts.

MATLAB Code