Methods and systems for cell labeling and imaging

A method for delivering a substance into a cell, comprising:

• (a) providing a microfluidic device, wherein:
• the microfluidic device comprises a channel that comprises a first wall comprising a first interior surface and a second wall comprising a second interior surface,
• the first wall and the second wall extend along a flow direction,
• the microfluidic device comprises a compressive element comprising a plurality of ridges connected to the first wall and extending towards the second interior surface,
• each of the plurality of ridges comprises a ridge surface that forms a gap with the second interior surface,
• each of the plurality of ridges comprises a material having a modulus from 1 to 100 kPa,
• each of the plurality of ridges has a rectangular cross-sectional profile in a plane perpendicular to the first interior surface, and
• the microfluidic device comprises a fluid within the microfluidic device, wherein the fluid comprises the cell and the substance, and wherein the substance is an imaging agent;
• and
• (b) subjecting the fluid to flow through the channel in contact with the compressive element, wherein:
• a height of the gap is smaller than a diameter of the cell, causing the cell to compress as the cell passes through the gap, and
• the contact causes formation of at least one pore in a membrane of the cell, wherein the at least one pore enables an entry of the substance into the cell.