Which type of pump should you choose? Syringe, peristaltic, piston and micropump compared
Transporting, dosing or dispensing liquids sounds simple, but the choice of the right pump type determines the accuracy, the lifetime and the integration complexity of your system. This article takes you through the four most commonly used pump principles for laboratory and OEM applications and helps you make the right choice.
⏱ approx. 9 minutes reading time
The five selection criteria
Before choosing a pump type, you need to answer five questions. Together, the answers determine which principle best suits your application.
What volume do you need to transport or dispense?
Are we talking about nanolitres for cell culture, microlitres for diagnostics, or millilitres for continuous process streams? Each pump type has an optimal working range.
What accuracy and repeatability do you need?
For quantitative analysis, a CV (coefficient of variation) of less than 0.5% is required. For simple liquid transport, 5% is more than sufficient. Know what your process specification requires.
What are the properties of the medium?
Aggressive chemicals, biological samples, viscous buffers, saline solutions, particles in suspension: the choice of pump material depends entirely on what passes through it.
May the medium come into contact with the pump?
In sterile applications or with high-purity reagents, contact with mechanical components is undesirable. A peristaltic pump or a diaphragm micropump offers a fully isolated fluid path.
Continuous or discontinuous?
Continuous flow, pulsed dispensing or precise discrete volume dosing each place different demands on the pump principle.
Tip for OEM design
In automated analysers and diagnostic instruments, one of the four types below is almost always used. The choice is rarely final at an early design stage, so design your system in such a way that the pump type can be replaced later. Connection dimensions and electrical interfaces are standardised per pump type.
1. Syringe pump: High precision with accurately defined volumes
Operating principle
A syringe pump drives a plunger through a cylinder (the syringe) using a stepper-motor-driven lead screw. The movement of the plunger is completely linear and precisely controllable. Each step of the motor corresponds to a fixed volume of liquid that is drawn in or expelled. By setting the step size and movement speed in software, you can precisely define flow rate, dispensing volume and timing.
Syringe pumps are in principle bi-directional: the same pump aspirates and dispenses, depending on the direction of travel. They can be combined with a switching valve to separate supply and discharge.
Typical applications:
- HPLC sampling
- Pipetting robots
- Microfluidics
- Infusion systems
- Titration
Advantages
- Highest absolute accuracy of all types
- Fully programmable volume, speed and timing
- Bi-directional: aspirating and dispensing
- No pulsating flow at low flow rates
- Suitable for small volumes down to the nanolitre range
Disadvantages
- Limited reservoir: must be refilled
- No continuous flow without an additional valve and refill cycle
- Medium in contact with plunger and cylinder
- Higher complexity and cost in OEM integration
- Sensitive to air bubbles in the fluid path
Take care with aggressive media
The plunger and the syringe barrel material must be compatible with the medium. With concentrated acids, solvents or biological samples, PTFE or glass syringes are necessary. Metallic parts in the fluid path can cause trace contamination in analytical applications.
2. Peristaltic pump: Fluid path completely isolated from the pump
Operating principle
A peristaltic pump works by squeezing a flexible tube with rotating rollers or fingers. The medium is located exclusively in the tube and never comes into contact with the mechanical parts of the pump. The peristaltic motion pushes the liquid in the direction of rotation. The flow rate is determined by controlling the rotation speed.
The tube is the only consumable part. Pump performance decreases as the tube ages or deforms under pressure, so regular replacement is necessary. Tube life depends on the medium, the pressure and the cycle time.
Typical applications:
- Bioreactors
- Chromatography buffers
- Sterilisable systems
- Waste removal
- Chemical dosing
- Cell culture
Advantages
- Liquid never touches mechanical parts
- Ideal for sterile and contamination-sensitive media
- Easy to clean: replacing the tube is sufficient
- Self-priming, even with air in the line
- Bi-directional by reversing the motor direction
- Wide range of tube materials
Disadvantages
- Pulsating flow at low flow rates
- Tube ages and must be replaced periodically
- Lower accuracy than a syringe or piston pump
- Limited pressure capability
- Tube wear affects flow rate over time
3. Piston dispensing pump: Highest accuracy at high cycle counts
Operating principle
A piston pump displaces liquid via a precisely dimensioned piston in a cylinder. The incoming and outgoing flows are controlled by check valves. The position of the piston determines the dispensing volume with high repeatability. The piston is driven by a stepper motor with direct mechanical coupling, which enables sub-microlitre precision over millions of cycles.
The specific problem with traditional piston pumps is the vulnerability of the sealing element to wear. When the medium contains salt, small residual volumes dry on the piston to form salt crystals. Those crystals abrade the seal, which leads to leakage. Bio-Chem Fluidics has fundamentally solved this problem in the Maestro ULTRA with superhydrophobic piston coatings and low surface energy materials that completely prevent salt crystallisation.
Typical applications:
- IVD diagnostic instruments
- Clinical analysers
- Reagent dosing
- Haematology
- Urinalysis
- Biochemical assays
Advantages
- Exceptionally high accuracy and repeatability
- Optimised for high cycle counts (millions)
- Programmable dispensing volume up to 100%
- Maestro ULTRA: immune to salt crystallisation
- Zero scheduled maintenance with the ULTRA version
- RS-232, RS-485 or CAN interface
Disadvantages
- Medium in contact with piston and cylinder
- Not suitable for particles or abrasive suspensions
- No continuous flow: works per stroke
- Higher purchase price than simple peristaltic pumps
Bio-Chem Maestro ULTRA at Inacom
The Maestro ULTRA piston pump has been specially developed for IVD instruments in which concentrated salt solutions pose a risk. The superhydrophobic piston coating prevents salt crystals from adhering, so the seal remains intact. Available with an integrated 3-way valve, RS-232/485/CAN communication and manifold integration. Dispensing volumes from 100 to 5,000 µl.
4. Solenoid micropump (diaphragm pump): Compact dispensing with an isolated fluid path
Operating principle
A solenoid micropump is a diaphragm pump in which an electromagnetic coil attracts and releases a flexible diaphragm. When attracted, a vacuum is created in the pump chamber, drawing liquid in via the inlet check valve. When released, a spring pushes the diaphragm back and a precise volume is expelled via the outlet check valve. The coil completely isolates the electrical operation from the fluid path: the medium never touches the solenoid.
Each complete on/off cycle corresponds to one discrete dispense. Repeating the cycle creates a pulsating flow. The dispensing volume per cycle is factory-set and fixed; variation in volume is achieved by repeating the cycle, not by changing the stroke size.
Typical applications:
- Waste stream removal
- Chemical dosing
- Sterilisation systems
- Compact OEM instruments
- Point-of-care diagnostics
- Water analysis
Advantages
- Liquid completely isolated from the solenoid by a diaphragm
- Very compact and lightweight for OEM integration
- Self-priming up to 1.3 m below the pump
- Inert material combinations: PTFE, PEEK, PPS, POM
- Continuous operation possible at 2 Hz
- Manifold mounting for multi-pump assemblies
- No external interrupters or valves required
Disadvantages
- Volume per cycle is fixed, not adjustable without a different model
- Pulsating output, no continuous liquid flow
- Low maximum pressure: optimal at ± 0.035 bar back pressure
- Limited accuracy compared with a syringe or piston pump
- Not suitable for viscous or particle-laden media
Bio-Chem Fluidics Micro-Pumps at Inacom
The 120SP, 130SP, 139SP (manifold) and 150SP series offer discrete dispensing from 20 to 250 µl per cycle in fully inert versions. The 130SP is available with a PTFE body for the most aggressive applications. Manifold assemblies are available for systems with multiple pumps on a single block, including isolation valves and selection valves.
Comparison table: the four types at a glance
| Criterion | Syringe | Peristaltic | Piston | Micropump |
|---|---|---|---|---|
| Accuracy | High | Moderate | High | Moderate |
| Repeatability | <1% CV | 1–5% CV | <0.2% CV | ±5% CV |
| Volume range | nl to ml | µl to l/min | 100–5000 µl | 20–250 µl/cycle |
| Continuous flow | No | Yes | No | Pulsed |
| Medium contact | Yes | No (tube) | Yes | No (diaphragm) |
| Aggressive media | With the right materials | Yes | With the right materials | Yes (PTFE body) |
| Maintenance | Syringe periodically | Tube periodically | Zero (ULTRA) | Minimal |
| OEM compactness | Medium-sized | Medium-sized | Medium-sized | Very compact |
| Salt resistance | Limited | Good | Excellent (ULTRA) | Good |
| Typical use | Analysis, titration, microfluidics | Biotech, continuous dosing | IVD, clinical diagnostics | Compact instruments, dosing |
When do you choose which type?
Do you need absolute accuracy with small volumes (nanolitres to microlitres)?
For the highest precision with very small volumes, a syringe pump is the right choice. Each step of the motor corresponds directly to a volume of liquid.
Syringe pump
Must the medium absolutely not come into contact with mechanical pump parts?
In sterile applications, biological samples or hazardous liquids where contact contamination is unacceptable, the peristaltic pump or the solenoid micropump is the first choice.
Peristaltic or micropump
Does your system run 24/7 with millions of cycles and does the medium contain salts or buffers?
The Bio-Chem Maestro ULTRA piston pump has been specifically designed for this situation. Salt crystallisation is the most common failure scenario in diagnostic instruments, and the ULTRA is completely immune to it.
Piston
Are you designing a compact OEM instrument with limited space and simple electrical integration?
The solenoid micropump scores best on compactness, simplicity and ease of OEM integration. Manifold mounting allows multiple pumps on a single block.
Micropump
Do you need continuous, pulse-free flow over a wide flow range?
Only the peristaltic pump delivers truly continuous flow. Consider a double head to compensate for a pulsed flow, or use a damping volume.
Peristaltic
Do you want zero scheduled maintenance for the pumps in an end-user instrument?
The Maestro ULTRA piston pump is the only type designed to be completely maintenance-free. No tube replacement, no piston change, no calibration resets.
Piston
Combinations are common in complex instruments
In a modern IVD analyser, several pump principles often work together. A syringe pump for accurate reagent distribution, a piston pump for the main dispensing, and a micropump for waste removal. Choose the best type for each sub-function and thereby optimise the overall system.
