Coulter counter

Coulter counter
Coulter Principle. The transient current drop is proportional to the particle volume.
The tip of the Coulter counter in a buffer solution, counting cells in solution.

A Coulter counter [1] [2] is an apparatus for counting and sizing particles suspended in electrolytes. It is used for cells, bacteria, prokaryotic cells and virus particles[3].

A typical Coulter counter has one or more microchannels that separate two chambers containing electrolyte solutions. As fluid containing particles or cells is drawn through each microchannel, each particle causes a brief change to the electrical resistance of the liquid. The counter detects these changes in electrical resistance.

Cells, being non-conducting particles, alter the effective cross-section of the conductive microchannel. If these particles are non-conducting, the electrical resistance across the channel increases, causing the electric current passing across the channel to briefly decrease. By monitoring such pulses in electric current, the number of particles for a given volume of fluid can be counted. The size of the electric current change is related to the size of the particle, enabling a particle size distribution to be measured, which can be correlated to mobility, surface charge, and concentration of the particles.

An American inventor named Wallace H. Coulter was responsible for the theory and design of the Coulter Counter. He first devised the theory behind its operation in 1947 while experimenting with electronics. Coulter determined that electrical charge could be used to determine the size and number of microscopic particles in a solution. This phenomenon is now known as the Coulter Principle.

The Coulter Counter is a vital constituent of today's hospital laboratory. Its primary function being the quick and accurate analysis of complete blood counts (often referred to as CBC). The CBC is used to determine the number or proportion of white and red blood cells in the body. Previously, this procedure involved preparing a blood cell stain and manually counting each type of cell under a microscope, a process that typically took a half hour.

Coulter Counters have a wide variety of applications including paint, ceramics, glass, molten metals and food manufacture. They are also routinely employed for quality control.

Other cell counting technologies that employ similar systems are also used, one of these being the CASY cell counting technology. These systems have some differences but operate on similar principles.

Due to the simple construction of these devices and the reliable sensing method, Coulter devices have found application in a broad range of particle analyses from blood cells to polymeric beads, DNA, virus particles and even metal ions. Quantitative measurements of the size and concentration of micro and nano scale particles has been accomplished using Coulter counters with reduced microchannel size so that particles pass one by one from one chamber to the other. Because this would substantially extend measurement times, multiple microchannels are used to reduce measurement times by counting particles in parallel with one another.

Another use of the Coulter principle is found in Scanning Ion Occlusion Spectroscopy (SIOS). Here a deformable membrane with a single nano-size aperture is used in order to characterize individual nano-scale particles during their transition across driven by either pressure or an electric field.


References

  1. ^ W.R. Hogg, W. Coulter; Apparatus and method for measuring a dividing particle size of a particulate system; United States Patent 3557352
  2. ^ U.S. Patent 7,397,232 Coulter counter
  3. ^ R.W. DeBlois, C.P. Bean (1970). "Counting and sizing of submicron particles by the resistive pulse technique". Review of Scientific Instruments 41 (7): 909–916. Bibcode 1970RScI...41..909D. doi:10.1063/1.1684724. 

External links

  • http://web.mit.edu/invent/iow/coulter.html
  • US 2656508  Means for counting particles suspended in a fluid, October 20, 1953, Wallace H. Coulter
  • "Dynamically resizable nanometre-scale apertures for molecular sensing"; Stephen J. Sowerby, Murray F. Broom, George B. Petersen; Sensors and Actuators B: Chemical Volume 123, Issue 1 (2007), pages 325-330

Wikimedia Foundation. 2010.

Поможем написать реферат

Look at other dictionaries:

  • Coulter counter — Coul·ter counter (kōlґtər) [Wallace H. Coulter, American engineer, 20th century] see under counter …   Medical dictionary

  • Coulter counter — Particle counter used for bacteria or eukaryotic cells; works by detecting change in electrical conductance as fluid containing cells is drawn through a small aperture. (The cell, a non conducting particle, alters the effective cross section of… …   Dictionary of molecular biology

  • Coulter counter — an automated instrument for performing blood counts, based on the principle that cells are poor electrical conductors compared with saline solution …   Medical dictionary

  • Coulter principle — Coulter patented several different implementations of the Coulter Principle. Image taken from US Patent #2,656,508. The term “Coulter Principle” refers to the use of an electric field for counting and sizing dilute suspensions of particles in… …   Wikipedia

  • Coulter — Coulter, a Scottish surname and place name, may refer to: Contents 1 Places 2 People 3 Other …   Wikipedia

  • Wallace H. Coulter — (February 17, 1913 – August 7, 1998) was an American electrical engineer, inventor, and businessman. He is best known for his discovery of the Coulter principle, which provided a methodology for counting, measuring and evaluating microscopic… …   Wikipedia

  • Particle counter — A particle counter is an instrument that detects and counts particles. Applications of particle counters are separated into two primary categories:*Aerosol particle counters *Liquid particle countersAerosol particle countersAerosol Particle… …   Wikipedia

  • Cell counting — is a general name for various methods for the quantification of cells in molecular biology and in medicine. Contents 1 The need for cell counting 2 Methods 2.1 Counting chamber 2 …   Wikipedia

  • Flow cytometry — Analysis of a marine sample of photosynthetic picoplankton by flow cytometry showing three different populations (Prochlorococcus, Synechococcus, and picoeukaryotes) Flow cytometry (abbreviated: FCM) is a technique for counting and examining… …   Wikipedia

  • Scientific phenomena named after people — This is a list of scientific phenomena and concepts named after people (eponymous phenomena). For other lists of eponyms, see eponym. NOTOC A* Abderhalden ninhydrin reaction Emil Abderhalden * Abney effect, Abney s law of additivity William de… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”