About the Structure and Working Principle of Pipette

Structure of Pipette

A pipette is a laboratory instrument used to measure and transfer a precise volume of liquid. There are various types of pipettes, but the basic structure includes the following components:

  1. Pipette Body:
    • The main body of the pipette is typically cylindrical and houses the internal mechanisms. It may be made of materials such as plastic or metal.
  2. Pipette Tip or Nozzle:
    • The lower part of the pipette body has a tapered or conical tip, often made of disposable plastic. This is the portion that comes into direct contact with the liquid being aspirated.
  3. Pipette Plunger or Button:
    • Located on the top of the pipette body, the plunger or button is pressed to aspirate and dispense liquid. The design may include a thumbwheel, push-button, or similar mechanism.
  4. Volume Adjustment Mechanism:
    • A volume adjustment mechanism is often present on the pipette body, allowing the user to set the desired volume for aspiration.
  5. Volume Display:
    • Many pipettes have a volume display or indicator that shows the selected volume setting. This could be a digital display, a rotating scale, or a simple numerical indicator.
  6. Ejector Button:
    • An ejector button is used to release the disposable tip after use. Pressing this button expels the tip safely into a waste container.
  7. Volume Lock:
    • Some pipettes feature a volume lock to prevent accidental volume changes during pipetting.
  8. Shaft or Barrel:
    • The shaft or barrel connects the body to the pipette tip. It may have a smooth surface or textured grip for ease of handling.

Working Principle of Pipette

The working principle of a pipette involves a combination of mechanical and air displacement mechanisms. Here are the general steps involved in the operation of a manual pipette:

  1. Aspiration (Liquid Intake):
    • The user selects the desired volume using the volume adjustment mechanism. With the pipette tip immersed in the liquid, the plunger is depressed. This creates a partial vacuum in the pipette, causing liquid to be drawn into the tip.
  2. Dispensing:
    • After aspirating the liquid, the pipette is moved to the desired location for dispensing. The plunger is then released slowly to allow the liquid to be dispensed drop by drop.
  3. Ejection of Tip:
    • Once the liquid is dispensed, the disposable tip can be ejected using the ejector button. This prevents cross-contamination between different liquids or samples.
  4. Accuracy and Precision:
    • The accuracy and precision of the pipette depend on the quality of its design and construction. Calibrated pipettes provide accurate and reproducible volume measurements.
  5. Air Displacement and Positive Displacement Pipettes:
    • Air displacement pipettes work by creating a vacuum to aspirate liquid, while positive displacement pipettes use a disposable piston or capillary to directly displace and aspirate the liquid.
  6. Calibration and Maintenance:
    • Regular calibration and maintenance are essential to ensure the accuracy of pipettes. Calibration involves adjusting the pipette to deliver the intended volume accurately.
  7. Variations:
    • Pipettes come in various types, including single-channel and multi-channel pipettes, each designed for specific applications. Multichannel pipettes can aspirate or dispense multiple samples simultaneously.
  8. Electronic or Digital Pipettes:
    • Electronic or digital pipettes have a built-in electronic mechanism for aspiration and dispensing. They often include features such as programmable modes, multiple volume settings, and ergonomic designs.

Standard 8 & 12 Channel Adjustable Pipettesuniversal-Non-Sterile-PP-Pipette-Tips

The pipette generally includes a control match button (different manufacturers have different designs, and this button is usually used to adjust the aspiration volume), tip push button, volume display window, sleeve, elastic nozzle, and tip.

The essence of the pipette is a piston pipette, which uses the principle of air discharge to work, and the capacity of the pipette is determined by the distance moved in the piston sleeve. According to different pipetting modes, it can be divided into built-in piston pipetting mode and external piston pipetting mode. Our daily use is the built-in piston pipetting mode.

Most of the tips with built-in piston pipetting mode are universal, but cross-contamination is more likely to occur during operation, and it is not suitable to suck high-viscosity liquids and volatile liquids; In the external piston pipetting mode, there is no air segment between the piston and the liquid. The piston is disposable. It can also achieve accurate pipetting for liquids with larger viscosity.

In addition, because there is no air gap, the sample is avoided. Due to the cross-contamination of aerosols that may occur in air contact, it is very suitable for the removal of precious reagents and biological samples.

For taking and dispensing of liquids when using the pipette, the pipette tip is disposable attachments, which are used to prevent cross-contamination from one sample to another.

When samples are aspirated into a pipette tip, a fine mist may be created, which can get into the pipette at the same time. And the aerosol can contaminate the next sample very easily even after you change the tip quickly. The fragment carried over from the previous sample might be just a tiny bit for most applications, but it still can cause big problems, especially for sensitive applications.

Sometimes, it is hard to disassemble and clean a pipette after every sample in most labs. To capture the aerosols, what we need is nothing but pipette tips, which can not only protect the pipette from contamination from samples but protect the samples from contamination from the pipette as well.

Made of polypropylene, Hawach pipette tips are clear to allow for an easy view of the contents of the tip. You can find Hawach pipette tips non-sterile and sterile, and both of them are DNase, RNase, DNA, and pyrogen-free.