Fabrication of a Hydrophilic Poly(dimethylsiloxane) Microporous Structure and Its Application to Portable Microfluidic Pump

Abstract

In this paper, we present a simple and low-cost fabrication technique of a novel hydrophilic poly(dimethylsiloxane) (PDMS) microporous structure (or microsponge) based on a modified sugar leaching technique. A surfactant, Silwet L-77 enabled us to achieve the wettability conversion of PDMS from hydrophobic to hydrophilic. The wettability changes of PDMS surfaces and microsponges were characterized at various weight percentages of Silwet L-77 and it was found that a hydrophilic PDMS microsponge containing 0.6% of Silwet L-77 rapidly absorbed water droplets. The average porosity of the fabricated PDMS microsponges was measured as 0.55. We have successfully demonstrated the hydrophilic PDMS microsponge as a portable pump for a microfluidic device. The hydrophilic PDMS microsponge was firmly bonded at the inlet of a PDMS microchannel via oxygen plasma treatment. A water-phase sample was easily loaded into the hydrophilic PDMS microsponge and it was released and injected into the microchannel by simply pushing the microsponge.

Hydrophilic surface modification of polydimetylsiloxane‐co‐2‐hydroxyethylmethacrylate (PDMS‐HEMA) by Silwet L‐77 (heptamethyltrisiloxane) surface treatment

“…It was observed after the treatment with 0.02% Silwet that the WCA decreased dramatically from 104.24° to 24.45°, and this decrease continues with increasing heptamethyltrisiloxane concentration (Figure A), which is consistent with previously reported works . Heptamethyltrisiloxane and related surfactants have been used to modify PDMS, with reported works indicating its effectiveness above critical wetting concentration . Unlike the previous works mentioned, we used physical adsorption of heptamethyltrisiloxane onto the PDMS‐HEMA surface in this work, with a low concentration used to achieve excellent wettability.…”

“…Because of its spreading and wetting properties, heptamethyltrisiloxane is widely used as a pesticide in agricultural industry, medical applications, and electronic printings to improve wettability of low energy surfaces …”

A Highly Sensitive Capacitive‐Based Soft Pressure Sensor Based on a Conductive Fabric and a Microporous Dielectric Layer

“…We chose this mixing ratio because, above this ratio, the resulting structure had a tendency to crack during separation from the 3D printed mold. Thereafter, the solution was poured into a 3D printed mold and oven‐cured at 70 °C for 2 h. By immersing the cured solution in an ultrasonic washing tank for 2 h at 80 °C, the granules dissolved, leaving behind micropores within the silicone elastomers and creating an open‐cell porous silicone structure . After ultrasonication, conductive fabrics were laminated onto both sides of the dielectric layer using a thin film applicator with Ecoflex 30 as an adhesion layer.…”

Conductive, multilayer scaffold with micro-porous structure for tissue engineering

“…Recent work has shown that highly porous, flexible PDMS can be achieved using sugar cubes as the leachable template. [22][23][24] Nevertheless, it is still relatively challenging to fabricate thin, micro-porous sheets with particulate leaching method as typical-grade sugar powder usually has a particle size in the range of 400 to 500 m. Hence, in this work, the sugar particles were first pre-sieved to fine mesh sizes prior to being used for constructing the micro-porous conductive bilayer material via particulate leaching.…”