Osaisiko joku selittää Coulterin periaatteen esim. solulaskennassa? Voiko sitä käyttää muussakin yhteydessä?

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En ole varma, mutta muistaakseni perustuu valo-optiikkaan.
Solut laitetaan liuoslaimennoksena kahteen eri kammioon, punasolut ja trombosyytit toisesta ja leukosyytit toisesta.
Laskimessa on eri kokoisia aukkoja, joiden läpi soluliuos suihkutetaan ja koon mukaan kone erittelee ja laskee.

Karkea muistelu ja voi olla päin puuta. Yritän löytää netiltä jotain.

Cell counter - Coulter counter

No juu, elektronistahan kaikki on nykyaikana.


Multisizer™ 3 COULTER COUNTER®
uses the Coulter Principle
(Electrical Sensing Zone Method)
for sizing and counting particles
The Highest Resolution for Sizing and Counting Particles

The most versatile and accurate particle sizing and counting analyzer available today. Using The Coulter Principle (Electrical Sensing Zone Method), also known as ESZ, the Multisizer 3 COULTER COUNTER provides number, volume, mass and surface area size distributions in one measurement, with an overall sizing range of 0.4 µm to 1,200 µm. Its response is unaffected by particle color, shape, composition or refractive index. The Coulter Principle is the absolute leading technology in high resolution and accuracy and it is further enhanced in the Multisizer 3 by using a Digital Pulse Processor (DPP). You will get the ultra-high resolution, multiple channel analysis and accuracy not provided by any other technology. It all makes the Multisizer 3 indispensable for any industrial or life science research project involving sizing and/or counting. Equally a powerful tool for quality control, it provides the analyst with a system which is easy to use, yet so technologically advanced that it is able to solve most particle sizing problems.

The Coulter Principle

Particles suspended in a weak electrolyte solution are drawn through a small aperture, separating two electrodes between which an electric current flows. The voltage applied across the aperture creates a "sensing zone". As particles pass through the aperture (or "sensing zone"), they displace their own volume of electrolyte, momentarily increasing the impedance of the aperture.

This change in impedance produces a pulse that is digitally processed in real time. The Coulter Principle states that the pulse is directly proportional to the tri-dimensional volume of the particle that produced it. Analyzing these pulses enables a size distribution to be acquired and displayed in volume (µm3 or fL) and diameter (µm). In addition, a metering device is used to draw a known volume of the particle suspension through the aperture; a count of the number of pulses can then yield the concentration of particles in the sample. ... sizer3.asp

The Coulter Particle Counter/Sizer

Counting: The device counts because whenever a particle (here represented with a crystal of something) goes through the hole, the electronic system detects a sudden and momentary increase in resistance (a partial interruption of current flow). and a green vertical line appears on the screen, as shown at the top. The oscilloscope is able to detect up to about 300,000 partial interruptions per second before Beer's law kicks in and you get out of linearity of true numbers and counts. This is because as concentration increases, the likelihood that two particles are going to try to squeeze through at the same time increases. Thus it might be that you must dilute your in some known way with buffer. (Why a saline buffer? To conduct the current, of course!)

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1/2 LL
Osaisiko joku selittää Coulterin periaatteen esim. solulaskennassa? Voiko sitä käyttää muussakin yhteydessä?

Yllähan tuo on selitetty kuvankin kanssa, mutta lyhyesti sanottuna kyseisessä menetelmässä mitataan volyymijohteessa tapahtuvia impedenssin muutoksia (tai virran tai jännitteen, ekvivalentisti) kahden elektrodin järjestelmässä, eli periaatteessa kyse on aivan tavallisesta impedanssimittauksesta. Solu tai lähes mikä tahansa muukin sopivan kokoinen partikkeli syrjäyttää tietyn, tilavuudestaan riippuvan määrän volyymijohdinta (ioneita sisältävä neste) ja tämä aiheuttaa muutoksen elektrodien välisessä jännitteessä. Coulterin mukaan kyseinen jännite-ero on verrannollinen syrjäytettyyn volyymiin, eli mittausraossa olevan partikkelin kokoon.

Ideana on tietysti järjestää mittaus niin, että mittausraossa on kerrallaan vain yksi partikkeli, muutoinhan tulos tulkittaisiin väärin.

"between the click of the light; and the start; of a dream"



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