A compact and versatile microfluidic probe for local processing of tissue sections and biological specimens

TL;DR

The paper introduces a compact, versatile microfluidic probe designed for precise local processing of tissue sections and biological specimens, compatible with standard lab equipment and capable of handling complex surface topographies.

Contribution

Development of a compact, user-friendly microfluidic probe with height compensation and rapid liquid switching for local tissue and cell processing.

Findings

Able to scan 45x45 mm^2 areas with 15 um accuracy

Successfully patterned tissue with height differences up to 750 um

Performed local staining on melanoma tissue sections using the probe

Abstract

The microfluidic probe (MFP) is a non-contact, scanning microfluidic technology for local (bio)chemical processing of surfaces based on hydrodynamically confining nanoliter volumes of liquids over tens of micrometers. We present here a compact MFP (cMFP) that can be used on a standard inverted microscope and assist in the local processing of tissue sections and biological specimens. The cMFP has a footprint of 175 X 100 X 140 mm^3 and can scan an area of 45 X 45 mm^2 on a surface with an accuracy of +-15 um. The cMFP is compatible with standard surfaces used in life science laboratories such as microscope slides and Petri dishes. For ease of use, we developed self-aligned mounted MFP heads with standardized chip-to-world and chip-to-platform interfaces. Switching the processing liquid in the flow confinement is performed within 90 seconds using a selector valve with a dead-volume of approximately 5 uL. We further implemented height-compensation that allows a cMFP head to follow non-planar surfaces common in tissue and cellular ensembles. This was shown by patterning different macroscopic copper-coated topographies with height differences up to 750 um. To illustrate the applicability to tissue processing, 5 um thick M000921 BRAF V600E+ melanoma cell blocks were stained with hematoxylin to create contours, lines, spots, gradients of the chemicals, and multiple spots over larger areas. The local staining was performed in an interactive manner using a joystick and a scripting module. The compactness, user-friendliness and functionality of the cMFP will enable it to be adapted as a standard tool in research, development and diagnostic laboratories, particularly for the interaction with tissues and cells.