AUTOMATION

Automation in Clinical Biochemistry

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Automation provides a mean by which an increased workload can be processed rapidly and with reproducible results.

The quality of results is controlled by running the samples of known values(standard) with every batch of test.

An autoanalyser may be fully automated or semiautomated which needs a part to performed manually.

With the growing demand for investigation, it is becoming inevitable to replace manual operation by mechanical devices for fast result on a large number of specimens.

Advantages of an Autoanalyser

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Two or more assays may be performed simultaneously.

Precision is superior to that of the manual method.

Calculations may not be required.

A large number of samples may be processed with minimal staff time.

Disadvantages of an Autoanalyser

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Many systems are impractical for small number of specimens. Therefore, manual methods are still necessary when there is smaller work load.

Instrument failures do occur, back-up procedures must be available.

It needs additional training of the staff about the working, maintenance and potential problems of the machine.

may be limitations to the methodology that can be used for automated systems.

Expensive to purchase and maintain.

TYPES OF AUTOMATED ANALYSER

Autoanalysers

Continous Flow Analysis
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   a) Single
   b) Multi channel
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Discrete
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   a) End point
   b) Reaction rate
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Centrifugal
Thin film(dry reagent)

Working Principles Of Discrete Analysers

Generally they are similar to the modular arrangement of the continuous flow system.

1) Sampler
This module aspirates the sample and transfer it with diluents to a tube held in reaction unit.

2) Reaction Unit
The reaction unit may have an incubator as an integral part for temperature regulation. The other reagent are added as the reaction proceeds.

3) Measuring unit
This measures the chemical change either by the end-point method or by reaction rate method.

4) Display unit
The result is usually displayed in a digital form, stored in the computer memory until deleted or print out.

CENTRIFUGAL ANALYSER

This type,the reaction takes place in the rotor of a centrifuge. The system consist of:

1) Rotor Disc
-This is a disc which can be spun at a high speed by vertically mounted electric motor. The upper surface of the disc has concentric rings of specially designed cavities, forming 3-4 discrete wells along the radius.

2) Photometer
-A photometer is mounted near the periphery of the rotor disc in such a way that its light path is parallel to the axis of rotation(vertical).

THIN-FILM OR DRY CHEMISTRY AUTOANALYSERS

Thin film analysers are discrete analysers.
-they use dry reagents spread in extremely thin layers on a plastic slide to which serum specimen is added. The system consist of:

a) Plastic chip
-the serum specimen provides the solvent necessary for the reaction

b) Reflectance Spectrophotometer
-as the coloured end product reaches the defined area, it is read by a reflectance spectrophotometer.

Modification of Dry chemistry Analysers

The dry chemistry technology in its modified form, is also used for ‘stick test’ for simple analysis such as blood glucose, INR etc.
In the system, a small microprocessor is attached to the reflectometer which simplifies calculation, calibration and overall operation.

Use of automatic measuring devices

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Automatic pipettes
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Hand-operated mechanical pipette
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Automatic dispensers
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Automatic diluters
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CONTINUOUS FLOW SYSTEMS

Sampler -

this consists of circular tray with separate cups for samples along its periphery. The amount of sample or wash solution aspirated is regulated by an electrical timing device which controls the pumping rate and dwell time of the probe in each cup. A bar coding system is used for specimen identification.
Proportionating pump - This module represents the use of different sizes of pipettes to add varying volumes of reagents to the reaction mixture in manual methods. A peristaltic action is produced by a series of rollers passing along a set of plastic tubes parallel to each other.
Manifold - The manifold may have 3 or more submodules which can removes protein, mix reagent and incubate at the desired temperature.

-The common submodules are the dialyser, mixing coils and incubator bath.
Colorimeter - The colorimeter continuously measures the absorbance of the solution which is passing through the flow cell, at a given wavelength.
Recorder - The light transmitted by the coloured solution causes a voltage change in the Photodetecter. This voltage is constantly measured and recorded by the recorder.