Curved Microwell Arrays Created by Diffusion-Limited Chemical Etching of Artificially Engineered Solids

Abstract

A new method based on diffusion-limited chemical etching has been developed for the productions of ordered arrays of curved microwells. Fiber-drawing nanomanufacturing is used to make ordered glass composites with controlled structure and composition. The differential chemical etching of two glasses in the composite preferentially etches one glass material away and generates ordered microwell arrays. The microwells can be replicated onto polymer films to form microdome arrays. Monte Carlo simulation illustrates the diffusion-controlled etching process. The etched microwells have been used to prepare micro/nanocrystals of proteins and inorganic materials with controlled sizes.

A review on microwell and microfluidic geometric array fabrication techniques and its potential applications in cellular studies

“…Illustration of: A, wet chemical etching; and B, dry etching on glass surface. The mask defined layer is added onto the top of the glass composite material followed by a chemical etchant (buffered HF for wet etching and CF 4 for dry etching), which selectively etches the glass and forms the desired microwells [ 157,160 ] …”

“…With excimer lasers, the amount of energy transferred to the strongly absorbing material, like polyester polymeric films, may suffer bond breakage and vaporization. On the other hand, multiphoton absorption observed 2 Huang et al [30] PDMS Sims [37] Epoxy resin [143] Photo- 1.8 × cells per mm 2 Moeller et al [49] SU [150] PDMS Honeycomb concave, and Yang et al [13] Silicon [219] (Continues) Tu et al [159] Agarose High-throughput analysis … Ostuni et al [44] Air Xu et al [114] Capillary Heo et al [271] Micromoulding PEG [272] Micro- [273] Embossing/ High-throughput screening 10 6 cells per mL Forget et al [118] Ice-lithography PDMS Park et al [156] Chemical [157] through weak lasers, such as CO 2 lasers may experience thermal depolymerization and melting. Melting of the polymeric material results in the conical feature's formation and differ from other microfabrication techniques such as mechanical drilling.…”

“…Deposition Formation F I G U R E 7 Schematic illustration of microwells formation using injection moulding: A, B, SU-8 mould with a designed patterned is used to attain desired feature on a coated nickel layer by UV photolithography. Cavities formed for self-alignment after removing SU-8 layers with top and bottom side; and C, illustration of the top and bottom side of mould insertion with desired microwell features on moulded substrates [171] Glass , which selectively etches the glass and forms the desired microwells [157,160]…”

“…Study of the biological effect of drug on a single-cell Medium 1.0 × cells per well Park et al [143] Photo- Yang et al [13] Silicon et al [219] (Continues) Tu et al [159] Agarose Gel Circular/ Cells entrapment High (~90%) 500 000 cells per well Xue et al [151] PDMS High-throughput analysis … Ostuni et al [44] Air Xu et al [114] Capillary format Low ≤100 cells per well Tang et al [93] Milling High 1000 cells per well Thomsen et al [91] Focused [272] Micro- et al [69] Prototyping [273] Embossing/ High-throughput screening 10 6 cells per mL Forget et al [118] Ice-lithography PDMS Ma et al [157] through weak lasers, such as CO 2 lasers may experience thermal depolymerization and melting. Melting of the polymeric material results in the conical feature's formation and differ from other microfabrication techniques such as mechanical drilling.…”

Facile Fabrication Method of Conical Microwells Using Non‐Uniform Photolithography

“…Several fabrication methods for tapered‐bottom microwells have been utilized successfully such as laser micromachining, [ 21–23 ] chemical etching, [ 24 ] micromilling, [ 25 ] inkjet printing, [ 26 ] photolithography, [ 27 ] and ice lithography. [ 28 ] Laser micromachining based on the selective melting of polymeric materials with focused laser heating, requires expensive and specialized equipment.…”