Role of BioMEMS in cell manipulation

Cells are about 5 to 20 µm in size, the same scale as microchannels, so BioMEMS devices can handle single cells gently and precisely.

Functions

• Trapping and positioning: microwells, hydrodynamic traps, optical or dielectrophoretic traps.
• Sorting and separation: by size, shape, charge, magnetic label or electrical properties.
• Focusing and counting: sheath flow and inertial focusing; on-chip flow cytometry.
• Lysis and sample preparation: release DNA, RNA or proteins.
• Culture and stimulation: organ-on-chip and gradient generators.
• Single-cell analysis: read-out of one cell at a time.

Techniques

Technique	Force used
Dielectrophoresis (DEP)	Non-uniform AC field acts on polarisable cells
Magnetophoresis	Magnetic force on cells tagged with magnetic beads
Acoustophoresis	Acoustic radiation force from standing waves
Optical tweezers	Focused laser light traps a cell
Hydrodynamic and inertial	Channel geometry and flow; label-free

Advantages

Tiny sample volume, high throughput, gentle handling, label-free options and integration with detection.

Exam tip

Mention at least three techniques and one application, such as circulating tumour cell isolation.