In the fields of modern analytical chemistry, biotechnology, pharmaceutical research and development, environmental monitoring, and industrial process control, there is an increasing demand for precise, stable, and automated processing of liquid samples. As a key component in achieving this goal,Liquid injection pumpThe Liquid Sampling Pump plays a crucial role. It is not only a "bridge" connecting samples and analytical instruments, but also a core guarantee for ensuring the accuracy and repeatability of experimental data. From high-performance liquid chromatography (HPLC) to automatic biochemical analyzers, from microfluidic chips to industrial online monitoring systems, their fluid control capabilities support the precise operation of modern technology.

1、 Core functions

It is a precision pump used for precise extraction, transportation, and metering of trace or small volume liquids. Its main function is to quantitatively and uncontaminated introduce the test sample or reagent from the storage container into the analysis system (such as chromatography column, detection cell, reaction chamber, etc.). Unlike ordinary transfer pumps, the core requirements of an injection pump are precision, repeatability, low pulsation, corrosion resistance, and biocompatibility.

2、 Main types and their working principles

According to the driving mode and structural characteristics, liquid injection pumps are mainly divided into the following categories:

注射泵 （SyringePump）

Principle: The piston is driven by a high-precision stepper motor or servo motor to perform linear motion in a closed syringe barrel, achieving the inhalation and ejection of liquid.

Features: High precision (up to nanoliter level), stable flow rate, minimal pulsation, easy to achieve precise gradient elution (in HPLC). But the flow range is limited and requires regular replenishment of liquid, which is not suitable for long-term continuous operation.

Application: Laboratory research, microinjection HPLC、 Microfluidic experiments.

Peristaltic Pump

Principle: Use a set of rollers or pressure blocks to periodically squeeze and release a section of elastic hose, suck in liquid through the negative pressure generated by the squeezing, and use the elasticity recovery of the pipe wall to push the liquid forward.

Features: The liquid only comes into contact with the inner wall of the hose, with no cross contamination, easy to replace pipelines, simple maintenance, and can transport liquids containing particles or viscous substances. But the pulsation is large, the accuracy and long-term stability are relatively low, and the hose is prone to fatigue.

Application: Cell culture, bioreactor, water treatment, food and beverage, occasions requiring sterility or contamination prevention.

DiaphragmPump

Principle: The flexible diaphragm is driven back and forth by electromagnetic, motor or pneumatic means to change the pump chamber volume, and combined with a one-way valve to achieve liquid suction and discharge.

Features: Compact structure, strong self-priming ability, dry operation, good corrosion resistance (diaphragm can be made of different materials). Electromagnetic driven micro diaphragm pumps are commonly used in portable devices and online analyzers.

Applications: Gas sampling (carrying solutions), portable detectors, small water treatment equipment, automotive exhaust analysis.

Piston Pump

Principle: Similar to an injection pump, but usually using a reciprocating plunger to work inside the pump cylinder, controlling the flow direction through a one-way valve to achieve continuous or pulse delivery.

Features: Able to generate high pressure, wide flow range, commonly used in situations requiring high pressure transmission (such as UHPLC). Multiple plunger designs (such as dual plunger and triple plunger) can significantly reduce pulsation.

Application: High performance liquid chromatography (HPLC/UHPLC), supercritical fluid chromatography (SFC), high-pressure reaction system.

Gear Pump and Screw Pump

Principle: Using the rotation of gears or screws that mesh with each other, the liquid is sealed from the suction end and pushed towards the discharge end.

Features: Stable flow rate, small pulsation, suitable for conveying viscous liquids. But it requires high cleanliness for liquids, is prone to wear, and may generate shear forces that affect biomolecules.

Application: Industrial process control, lubricant transportation, high viscosity fluid treatment.

3、 Development Trends and Challenges

With the advancement of technology,Liquid injection pumpIt is developing in the following direction:

Miniaturization and Integration: Meet the needs of microfluidics and Lab-on-a-Chip, and develop micro pumps for nanoupgrades and even skin upgrades.

Intelligence and Networking: Integrating sensors (pressure, flow, bubble detection) to achieve self diagnosis, self calibration, and remote monitoring, integrated into the Internet of Things (IoT) system.

Low pulsation and high precision: By optimizing the driving algorithm (such as sine drive) and designing multiple pump heads, pulsation is further reduced and the stability of the ultra-high pressure system is improved.

New materials and processes: Develop pump bodies and sealing materials that are more corrosion-resistant, have low adsorption, and have a longer lifespan, reducing damage to biological samples.

Green and Sustainable: Reduce energy consumption, decrease solvent consumption (such as flow chromatography pumps), and use environmentally friendly materials.

The performance of the liquid injection pump directly determines the reliability and data quality of the entire system. With the deepening of scientific research exploration and the upgrading of industrial demand, the requirements for injection pumps will continue to increase. In the future, more intelligent, precise, and reliable injection pumps will continue to push the boundaries of science and technology, providing solid technical support for life and health, environmental protection, material innovation, and intelligent manufacturing. Choosing and applying appropriate injection pumps is a crucial step in building efficient, accurate, and reliable experimental or production systems.