Precision MEMS Nano-Cutting Device for Cellular Microsurgery

An important tool for biological research and microsurgery is a microdevice for the cutting and isolation of subcellular neuronal components such as axons and dendrites for analysis or microsurgery. We have fabricated an easy-to-use, inexpensive and robust MEMS device with a nanoscale cutting tool that performs highly reproducible cutting of axons and dendrites. The device consists of a knife with an 20 nm-sharp edge ranging from 10–200 microns in length and is formed from molding conformally deposited silicon nitride over a potassium hydroxide-etched trench in <100>-oriented single crystal silicon. Knife surfaces are coated with a thin layer of liquid perfluorinated polyether to prevent adhesion of debris from cut targets. The knife is assembled onto a microfabricated suspension and frame consisting of serpentine flexures of single crystal silicon. These supporting structures help to properly orient the knife and control cutting force. We have used this assembled nano-cutting device to make reliable cuts of individual living dendrites and unmyelinated and myelinated axons from both adult and embryonic animal tissue. The cutting device was able to target and cut specific cell processes within a complex field and without disturbing surrounding structures. The cuts were sharp and repeatable, and microdevice’s performance was undiminished with repeated use.