Definition
A microplate centrifuge is a type of laboratory centrifuge equipment designed specifically for microplates. Microplates are standardized sample carrier plates commonly used in biochemistry, molecular biology, and other fields, usually containing 96-well, 384-well, or higher density well arrays. By generating a controllable centrifugal force, the instrument promotes the liquid in the microplate well to settle to the bottom of the well in a short time, or separates components of different densities in the well to meet the needs of routine operations such as sample preparation, reaction mixing, and liquid transfer and collection. The core of its design lies in adapting the rotor and cavity of the microplate to ensure the stability and uniformity of the centrifugation process.
Principle
Microplate centrifuges operate on the principle of centrifugal sedimentation. When the rotor drives the microplate to rotate at high speed, the sample is subjected to a centrifugal force that is much greater than gravity, which accelerates the sedimentation rate of particles in the sample or the separation of liquid layers. The centrifugal force depends on the rotational speed and the radius of rotation, and is commonly expressed as relative centrifugal force, and its calculation formula is:RCF = 1.118 × 10-5 × r × N2, among themRCFThe unit is the gravitational acceleration multiple (×g),ris the radius of rotation (cm),Nis the rotational speed (rpm). Instruments are usually equipped with adjustable speed and time settings to suit the separation requirements of different experimental steps.
Measurement method
The performance of microplate centrifuges is usually evaluated based on parameters such as speed accuracy, temperature control stability, and operating vibration levels. The rotational speed can be calibrated by means of a photoelectric tachymeter to ensure that the set value is within the allowable deviation from the actual value. Temperature control features that place a calibrated temperature probe in the chamber to monitor temperature fluctuations and uniformity at different set temperatures. Vibration levels can be measured outside the instrument base or cavity using a vibration gauge, and low vibration helps maintain sample integrity. In addition, the suitability of the microplate can be evaluated by observing whether the liquid in the wells settles uniformly after centrifugation and whether there is cross-contamination.
Influencing factors
The centrifugation effect is influenced by a variety of factors. Rotation speed and time directly affect the degree of separation. Too high a speed or time can cause over-compaction or damage to the sample, while insufficient can lead to incomplete separation. Rotor balance is related to the symmetry of microplate loading and running stability, and unbalanced loading may cause vibration and affect the consistency of separation. Temperature control is critical for temperature-sensitive experiments, such as certain biochemical reactions that need to be centrifuged at specific temperatures to prevent degradation. The material of the microplate itself and the shape of the bottom of the hole can also affect the liquid flow and particle settling behavior. In addition, environmental factors such as instrument placement leveling and power stability can also indirectly affect performance.
Applications
Microplate centrifuges are widely used in many non-clinical experimental testing fields. In molecular biology, it is used for precipitate collection after DNA/RNA extraction, liquid mixing and collection of PCR reaction plates. In cell biology, it can be used for cell sedimentation and supernatant removal of cell culture plates. In biochemical analysis, it is commonly used for the sedimentation of liquids after color development or washing steps on plates to improve detection consistency. In the field of food inspection, it can be used for rapid separation in sample preparation. In environmental monitoring, assist in the separation of particles from water samples or soil extracts. Its versatility makes it a common companion device in high-throughput screening, automated workflows.
Selection considerations
When choosing a microplate centrifuge, it is necessary to consider the experimental needs and instrument characteristics. In terms of suitability, it is necessary to confirm the type and number of microplates that the instrument rotor is compatible with, such as whether it supports 96-well, 384-well, deep-well plates, or PCR plates. In terms of performance parameters, the highest relative centrifugal force, temperature control range, and accuracy required are evaluated according to the characteristics of the sample. In terms of operating functions, you can pay attention to program storage capabilities, acceleration and deceleration gear adjustments, noise levels, etc. Safety features such as lid-lock mechanisms and imbalance detection help ensure safe operation. Ease of maintenance and calibration, difficulty in obtaining consumables should also be taken into account. The final choice should be based on real-world application scenarios, balancing performance, security, and cost.