Fabrication of a silicon μDicer for uniform microdissection of tissue samples

Abstract

Generating uniform tissue microfragments is important in many applications, including disease diagnostics, drug screening, spatial-omics, and fundamental wound healing and tissue regeneration studies. Common mechanical dissection methods, such as manual mincing, are imprecise and result in fragments with a broad range in size. This work aims to develop a microscale dicing device, referred to as the “μDicer,” consisting of a hollow array of blades spaced hundreds of micrometers apart. A tissue pushed through this array is diced into many microfragments simultaneously. The focus of this paper is on the fabrication process of the μDicer using a combination of isotropic and anisotropic etching in silicon. A single silicon oxide etch mask is used in a dry silicon etcher for both a tapered etch to form the microblades, and an anisotropic etch to form the through-holes in the hollow blade array. The use of a single mask reduces the mask fabrication time by more than twofold compared with two-mask approaches often used to generate similar etch features. The etch parameters and the design of the etch mask control the blade angles and the edge profiles of the blades. Specifically, the incorporation of “notches” in the two-dimensional mask design generates three-dimensional microserrated features on the blade edges. A custom, open-source etching model is also developed to facilitate the prediction of the etch profiles. Finally, a proof-of-concept application of the μDicer to dissect soft materials and tissues is demonstrated.

Microfluidic Surgery in Single Cells and Multicellular Systems

“…A limiting factor in microfluidic sectioning in a pure PDMS system is the ability of the PDMS blade to pierce stiff biological samples, as PDMS is relatively soft (Young’s modulus ∼ 2 MPa). , While noncontact hydrodynamic methods may be able to alleviate this issue simply by increasing the flow rate, another solution is to use a stiff material such as silicon (Young’s modulus ∼ 140 GPa) to fabricate the blades, as shown in the Biogrid by Wallman et al . Several other studies have devised silicon grids with sharp edges that can cut samples into 100–200 μm sized pieces. , However, they were not demonstrated on live samples and did not leverage microfluidic methods. An alternative approach is to utilize in situ direct laser writing to fabricate a blade structure made of a stiff photoresist (e.g., the Nanoscribe IP series photoresist has a Young’s modulus ∼ 1–4 GPa) directly inside a microfluidic channel .…”

Picosecond laser capture microdissection based on edge catapulting combined with dielectrophoretic force

“…The isolation of specific cells in biological tissues is the basis for studying the gene expression of heterogeneous cells and further understanding biological functions or disease mechanisms [ 11 ]. Laser capture microdissection is a powerful technique that enables precise extraction of cells from a tissue slice [ 12 ]. At present, nanosecond laser pulses are commonly used in commercial laser microdissection systems for cell separation [ 13 , 14 ].…”