ZnO Submicrometer Rod Array by Soft Lithographic Micromolding with High Solid Loading Nanoparticle Suspension

Abstract

Microfabrication by soft lithography has attracted increasing attention in recent years. Ceramic microfabrication by soft lithography normally utilizes ceramic precursor solutions or sol–gel process. However, the low solids loading of the starting materials compromises the fidelity of soft lithography, causing the aspect ratio of obtained submicrometer ceramic features to be very small. In this study, well‐dispersed, high solids loading ZnO nanoparticle suspensions are prepared by electrosterically stabilizing 20 nm ZnO nanoparticles. ZnO nanoparticle‐based submicrometer rod arrays with an aspect ratio around 1 are fabricated by micromolding the ZnO nanoparticle suspension into polydimethylsiloxane (PDMS) molds. Modified PDMS molds are exploited to optimize the filling depth of the suspension into the mold cavities, producing ZnO submicrometer rods with the same dimensions as the mold features. ZnO rods with various diameters and shapes are fabricated, and the effect of solids loading on soft lithography fidelity is discussed. A mechanism describing the effects of surface wetting on the fidelity of soft lithographic micromolding is proposed.

Preparation of Micro‐/Mesoporous SiOC Bulk Ceramics

“…Then, vacuum was applied to eliminate air bubbles and solvent (TEOS). To obtain monolithic specimens, PDMS molds were used and detailed preparation process can be found elsewhere . Briefly, PDMS prepolymer (Sylgard 184; Dow Corning, Midland, MI) with base and curing agents at 10:1 ratio was cast on a silicon core, which was placed under a vacuum chamber and subjected to a pressure of 10 mTorr for 30 min to remove air bubbles, then moved into an oven at 100°C for 60 min to solidify the PDMS.…”

Highly Porous SiOC Bulk Ceramics with Water Vapor Assisted Pyrolysis

“…The PDMS mold preparation process was standard in our lab. 29,30 PDMS prepolymer (Sylgard 184, Dow Corning, Midland, MI) with base and curing agents at 10:1 ratio was cast on a steel disk with ~18 mm diameter and ~6 mm thickness. The steel and PDMS prepolymer were placed in a vacuum chamber, subjected to a pressure of 10 mTorr for 30 min to remove air bubbles, and then moved into an oven at 100°C for 60 min to solidify the PDMS mold.…”

“…To obtain monolithic specimens, PDMS molds were used. The PDMS mold preparation process was standard in our lab . PDMS prepolymer (Sylgard 184, Dow Corning, Midland, MI) with base and curing agents at 10:1 ratio was cast on a steel disk with ~18 mm diameter and ~6 mm thickness.…”

Utilisation of micro- and nanoscaled materials in microfluidic analytical devices

“…Nevertheless, the degree of excellence of silicon micromachining techniques, the requirement of rapid prototyping of different microsystems allied with fact that silicon micromachining is a time consuming and expensive technique, drove the researchers to find new ways to construct microchannels using simpler procedures. Nowadays, the literature shows many alternative approaches for microchannel construction, including micromachining [20], soft lithographic micromoulding [21], hot embossing [22], laser ablation [23] or powder injection moulding [24].…”