Three-Dimensional Soft Material Micropatterning via Grayscale Photolithography for Improved Hydrophobicity of Polydimethylsiloxane (PDMS)

In this present work, we aim to improve the hydrophobicity of a polydimethylsiloxane (PDMS) surface. Various heights of 3D PDMS micropillars were fabricated via grayscale photolithography, and improved wettability was investigated. Two approaches of PDMS replication were demonstrated, both using a single master mold to obtain the micropillar arrays. The different heights of fabricated PDMS micropillars were characterized by scanning electron microscopy (SEM) and a surface profiler. The surface hydrophobicity was characterized by measuring the water contact angles. The fabrication of PDMS micropillar arrays was shown to be effective in modifying the contact angles of pure water droplets with the highest 157.3-degree water contact angle achieved by implementing a single mask grayscale lithography technique.

Properties and Applications of PDMS for Biomedical Engineering: A Review

Polydimethylsiloxane (PDMS) is an elastomer with excellent optical, electrical and mechanical properties, which makes it well-suited for several engineering applications. Due to its biocompatibility, PDMS is widely used for biomedical purposes. This widespread use has also led to the massification of the soft-lithography technique, introduced for facilitating the rapid prototyping of micro and nanostructures using elastomeric materials, most notably PDMS. This technique has allowed advances in microfluidic, electronic and biomedical fields. In this review, an overview of the properties of PDMS and some of its commonly used treatments, aiming at the suitability to those fields’ needs, are presented. Applications such as microchips in the biomedical field, replication of cardiovascular flow and medical implants are also reviewed.

Microfluidics 4: PDMS Chip Soft Lithography v2

Microfluidics materials are of various types and application-specific. PDMS is one of the most preferred and cost-effective solutions for research and low-volume manufacturing. After having the mold, PDMS replicas are generated by a technique called soft-lithography. This protocol describes the preparation of PDMS microchannels using SU8 molds, 3D Printed resin molds, and/or metal molds by the soft lithography technique, SLA printing, or CNC machining.

Microfluidics 4: PDMS Chip Soft Lithography v2

Microfluidics materials are of various types and application-specific. PDMS is one of the most preferred and cost-effective solutions for research and low-volume manufacturing. After having the mold, PDMS replicas are generated by a technique called soft-lithography. This protocol describes the preparation of PDMS microchannels using SU8 molds, 3D Printed resin molds, and/or metal molds by the soft lithography technique, SLA printing, or CNC machining.

Evaluation of Streptococcus mutans Adhesion to Stainless Steel Surfaces Modified Using Different Topographies Following a Biomimetic Approach

Bacterial adhesion to surfaces is the first step in biofilm formation, which leads to the development of conditions that may compromise the health status of patients. Surface modification has been proposed to reduce bacterial adhesion to biomaterials. The objective of this work was to assess and compare Streptococcus mutans adhesion to the surface of biomimetically-modified stainless steel using different topographies. Stainless steel plates were modified using a soft lithography technique following a biomimetic approach. The leaves from Colocasia esculenta, Crocosmia aurea and Salvinia molesta were used as surface models. Silica sol was synthesized using the sol-gel method. Following a soft lithography technique, the surface of the leaves were transferred to the surface of the SS plates. Natural and modified surfaces were characterized by means of atomic force microscopy and contact angle. Streptococcus mutans was used to assess bacterial adhesion. Contact angle measurements showed that natural leaves are highly hydrophobic, but such hydrophobicity could not be transferred to the metallic plates. Roughness varied among the leaves and increased after transference for C. esculenta and decreased for C. aurea. In general, two of the surface models used in this investigation showed positive results for reduction of bacterial adhesion (C. aurea and C. esculenta), while the other showed an increase in bacterial adhesion (S. molesta). Therefore, since a biomimetic approach using natural surfaces showed opposite results, careful selection of the surface model needs to be taken into consideration.

A nanomesh electrode for self-driven perovskite photodetectors with tunable asymmetric Schottky junctions

We report a new device architecture for self-driven photodetectors with tunable asymmetric Schottky junctions based on a nanomesh electrode. It is composed of a hexagonally ordered nanoelectrode array fabricated via the nanosphere lithography technique.

Enhanced crystallization by the virtue of the complete confinement of a ultrathin poly(3-hexylthiophene) film during the patterning process

The enhanced crystallization of the patterned poly(3-hexylthiophene) film based on the nanoimprinting lithography technique due to complete confinement.