Coulters

Coulters is a term used in multiple fields to describe different devices or components, most commonly in agriculture and in biomedical instrumentation.

In agriculture, a coulter is a sharp blade or wheel attached to plows, seed drills, or cultivators. It is mounted ahead of the main furrow opener to cut through crop residues and soil, creating a narrow, less-disturbed groove for seed placement. Coulters can be circular, flat knives, or other shapes, and may be fixed or adjustable. They help reduce soil resistance, improve seed-to-soil contact, and facilitate consistent furrows. Some systems employ double coulters to increase residue cutting, and coulters are used in both conventional plowing and no-till farming to prepare the seedbed without fully inverting the soil.

In biomedical instrumentation, a Coulter counter is a device that counts and sizes microscopic particles suspended in a fluid by measuring changes in electrical impedance as each particle passes through a small aperture. The method, known as the Coulter principle or electrical sensing zone technique, enables rapid enumeration of cells such as red and white blood cells and platelets. Since its development in the 1950s by Wallace H. Coulter, the technology has evolved into automated hematology analyzers that combine impedance measurements with optical or other methods to provide broader data on blood composition.

The term Coulter also appears as a surname and in various place names and brands. The word’s core meaning in its technical uses is that of a cutting or sensing element designed to interact with a material—soil, residue, or particles—in a controlled, measurement-oriented way.