Stroke-controlled aspiration and dispensing
Use step counts to organize aspiration, dispensing and refill for reagent addition, dilution and buffer dispensing in analytical instruments.
100 μL Precision Dispense Pump for Reagent Addition and OEM Integration
EA-100-PMMA is a precision dispense pump with a nominal capacity of 100 μL for microliter reagent addition, small-volume sample handling and reaction-liquid addition in analytical instruments. An acrylic (PMMA) head and ceramic piston work with a reciprocating stepper drive to aspirate and dispense measured volumes.
Ports are available in 1/4-28 UNF or M6, with 2000 steps per full stroke. Full-stroke accuracy and repeatability are both ≤0.5%, with an anticipated life of 5 million cycles. Optical feedback, valve assemblies and a controller can be supplied to integrate the microliter dispensing unit with instrument controls.
OEM customization includes PMMA, PCTG and PEEK head options, with zirconia ceramic, alumina ceramic, PEEK or sapphire pistons. Motor, port and fluidic component choices can be matched to reagent chemistry, available space and the dispensing sequence.
Application Areas:
IVD, Life Sciences, Laboratory Automation, Analytical Instruments
EA piston pump configurations
Select capacity, pump head material and accessories, then save different configurations for your inquiry.
| Nominal capacity | 100 μL |
|---|---|
| Pump head material | PMMA (polymethyl methacrylate); Transparent |
| Piston / seal | Ceramic / UHMWPE (ultra-high-molecular-weight polyethylene) |
| Fluid port | 2 × 1/4-28 UNF flat-bottom ports; M6 optional |
| Basic motor configuration | 1.8°; 2000 steps per full stroke |
| Nominal resolution | 0.05 μL/step (100 μL ÷ 2000 steps) |
| Other stroke configurations | 0.9°; 4000 steps per full stroke; 0.025 μL/step |
| Lead screw pitch | 1.27 mm |
| Mounting | 2 × M3; standard spacing 31.8 mm, wide bracket 42.8 mm |
| Accuracy / repeatability at 100% stroke | ≤0.5% / ≤0.5% |
| Accuracy / repeatability at 2% stroke | ≤2.0% / ≤1.5% (piston-travel test) |
| Backlash | ≤1.0%; validate compensation for precise dosing |
| Fluid pressure | <0.30 MPa |
| Expected service life | 5 million cycles (pure water, room temperature, 50 kPa back pressure) |
| Fluid / ambient operating temperature | 15–40 ℃ / 5–40 ℃ |
| Operating humidity | 30%–85% RH, non-condensing |
Nominal resolution is capacity divided by full-stroke steps, not the minimum reliable dose. 2% of 100 μL is 2 μL. Validate actual reagent results at this dose with the selected valves, tubing, back pressure and drive settings.
Low-range figures are tested by piston travel. Match the motor, optical sensor, valve and driver to the selected configuration; capacity or head material alone does not define all electrical options.
Features and advantages
EA uses a stepper motor to reciprocate the piston for aspiration and dispensing. Define dose volume, consecutive dispenses, fluid and cycle time before choosing capacity, wetted materials, valves and controls.
100 μL nominal capacity
Define dose volume and doses per cycle before comparing 100, 250 and 500 μL configurations. For small doses, also check refill timing and repeatability at the target operating point; do not select solely by maximum capacity.
Transparent head for visual inspection
The transparent head allows observation of filling and bubbles. PMMA (polymethyl methacrylate) is not resistant to alcohol or strong acids; both process and cleaning fluids must meet these material limits.
Select motor and feedback separately
Select the stepper motor, home sensor or encoder to suit the instrument. A home sensor detects the initial position; it does not provide closed-loop motion control.
Pump, valve and drive integration
Select valve assemblies and drivers for the fluid path and controls. Include aspiration, dispensing and valve switching in the complete cycle.
Define service life and maintenance conditions
Expected life: 5 million cycles with pure water at room temperature and 50 kPa backpressure. Saline or crystallizing fluids require flushing and shutdown procedures.
Choosing capacity, step angle and resolution
The nominal capacity is 100 μL. Define dose volume and doses per cycle before comparing 100, 250 and 500 μL configurations. For small doses, also check refill timing and repeatability at the target operating point; do not select solely by maximum capacity.
100 μL configuration comparison
| Step angle | Full steps per stroke | Nominal volume per step |
|---|---|---|
| 2000 steps | 0.05 μL/step | |
| 4000 steps | 0.025 μL/step |
Nominal step calculator
Nominal steps
200steps
10 μL ÷ 100 μL × 2000 steps = 200 steps
Nominal steps are for command conversion, not the minimum reliable dose or measured accuracy.Calculated from capacity and full-stroke steps; volume per step is rounded for display. Validate microstepping, backlash, bubbles, valves and tubing at the target volume.
Set compensation and dosing steps separately
Take up mechanical backlash after reversal before counting the effective dosing stroke. The ≤1.0% backlash figure is a pump specification; set compensation and valve timing for the actual circuit.
1% of the selected full stroke
2000 × 1% = 20 steps
Conversion example only; validate the actual compensation.Choosing head, piston and seal materials
Record composition, concentration, temperature and contact time for both working and cleaning fluids, then consider visibility or light shielding. This model uses a PMMA (polymethyl methacrylate) head. The table compares EA materials; changing the comparison does not change the model or supplied configuration.
Scroll horizontally to see all material limits and selection criteria.
| Head material | Main selection considerations | Limits and selection criteria |
|---|---|---|
| PMMA (Polymethyl methacrylate)Transparent · Current head | For fluid paths requiring direct observation of filling and bubbles. | Not resistant to alcohol or strong acids. Select another material if either the process or cleaning fluid contains them. |
| PCTG (Copolyester)Transparent | Compare with PMMA (polymethyl methacrylate) and PSU when a transparent head is needed. | Not resistant to strong acids, strong alkalis, sodium hypochlorite or “84” disinfectant. Transparency alone is not a reason to substitute it for PMMA (polymethyl methacrylate). |
| PSU (Polysulfone)Transparent | Consider specific grades when transparency, hydrolysis resistance and thermal stability matter. | General resin properties do not mean the pump can operate at high temperature or be steam-sterilized. Select according to the pump, seals and actual cleaning conditions. |
| PEEK (Polyether ether ketone)Opaque | Include in chemical compatibility comparisons when an opaque head is needed or the current material does not meet fluid requirements. | Check the specific chemical, concentration and temperature. PEEK is not universally resistant to all acids, alkalis and solvents. |
| PVDF (Polyvinylidene fluoride)Opaque | Consider when an opaque head is required and acids, salts or other chemical fluids are involved. | Check every process and cleaning fluid, especially alkaline and mixed formulations. Resin compatibility charts do not replace complete-pump testing. |
| PPS (Polyphenylene sulfide)Opaque | An opaque EA option; compare construction and material compatibility. | Confirm the actual grade, fluid and seal design before choosing a combination. Opacity does not establish chemical compatibility. |
| POM (Polyoxymethylene)Opaque | An opaque EA option; compare machining, construction and fluid requirements. | Check acids, oxidizing cleaners and prolonged immersion separately. Do not substitute based on the suitability of other plastics. |
| PET (Polyethylene terephthalate)Opaque | An opaque EA project option. | Confirm the actual resin grade and compatibility with the target fluid before proceeding to a prototype. |
Alcohol cleaning matters even with water-based working fluids.
PMMA (polymethyl methacrylate) restrictions also apply during cleaning. PCTG is limited with strong acids, strong alkalis and sodium hypochlorite. Reassess the full formulation when changing material; opacity alone does not imply corrosion resistance.
Piston: ceramic and PEEK are distinct
EA piston options include zirconia, alumina and PEEK. This page describes a ceramic piston. A PEEK piston requires separate wetted-path evaluation. Ceramic grade, surface and seal pairing depend on the supplied configuration.
Seal: assess with piston and fluid
Seals use UHMWPE (ultra-high-molecular-weight polyethylene). After changing the head material, check seals, piston, valves, tubing and fittings. For saline or crystallizing fluids, consider crystal damage and seal-flushing options.
General PSU, PEEK and PVDF properties are screening references, not confirmation of FOREACH resin suppliers or changes to pump temperature, pressure or validation requirements. References: PSU properties, PEEK chemical compatibility, PVDF chemical compatibility.
View material compatibility referencesMotor configuration, driver selection and wiring
Identify the motor by label, part number and wiring documents before selecting a driver. Step angle determines nominal steps; four- or six-wire construction determines winding connections. Do not infer all electrical parameters from the harness.
4-wire bipolar · 42 motor
| Rated phase current | 1.2 A/phase |
|---|---|
| Winding resistance (25 °C) | 2.8 Ω ±10% |
| Winding inductance (1 kHz) | 4.5 mH ±20% |
Four motor leads do not mean a four-position connector. The drawing shows assigned pins in a six-position connector; identify windings and pins from the drawing.
Match phase current, microstepping and acceleration/deceleration to the driver definitions. Rated phase current is not supply input current. Check current settings, then verify motion and temperature rise.
Wiring diagram
Distinguish the controller, driver and pump.
A stepper motor needs a matching driver. RS-232, RS-485 and CAN belong to the optional ISC1000 integrated driver, not the bare pump. Confirm valve, driver and closed-loop encoder options separately.
Commission motion settings in sequence
- First check component matching
- Check windings, rated phase current and driver settings, distinguishing peak from RMS. Confirm direction and sensor state using controlled motion first.
- Then set start and stop profiles
- Start with smooth starting and stopping, then adjust speed and acceleration/deceleration one parameter at a time. Accelerate before high-speed operation and decelerate before stopping.
- If vibration or lost steps occur
- Check start/stop profiles, mechanical load and fluid resistance, then evaluate microstepping and vibration isolation. Keep current within motor and driver limits; revalidate dose volume after adjustment.
Selecting and wiring the home sensor
The optical sensor detects the initial position for homing; an encoder provides a different type of motion feedback. They are not interchangeable. EA also offers no-sensor or custom-sensor options; three common configurations are compared below.
3-wire optical home sensor
Powered sensor with signal output; first verify board input levels and output mode.
| Wire | Connection and function |
|---|---|
| Brown | 5–24 V DC supply |
| Blue | Supply return |
| Black or white | Signal output; use the output for the supplied version and verify light-on/dark-on behavior |
The diagram shows two output modes. Not all shown wire colors belong to one three-wire harness.
Wiring diagram
Read blocked and unblocked states first. Confirm the input active level, homing direction and stop logic before automatic homing. Validate stopping clearance for the mechanism; do not copy step counts from other capacities or versions.
Working stroke and home position
- B: sensor transition point
- Moving upward, the piston enters the blocked region at B. AB is blocked; BD is unblocked. Check output levels against the selected sensor wiring.
- BC: normal working stroke
- The 1.8° configuration has 2000 full steps per full stroke, corresponding to a nominal capacity of 100 μL.
- A and D: mechanical limits
- AB and CD are end-clearance zones, not additional dispensing travel. Confirm clearances and stop positions for the current capacity and mechanism.
With a home sensor, initialization after each test cycle is recommended. Match stopping clearance to the mechanism, homing speed and stop logic to avoid mechanical contact.
Optical sensor photos
Ports, tubing and first-use procedure
Check threads and flat-bottom seals
Standard ports are 2 × 1/4-28 UNF flat-bottom; M6 is optional. Check thread, depth, tube OD, fitting and washer together. Identical threads do not guarantee identical sealing geometry.
Choose tubing for the dosing task
Compare rigid PTFE, FEP, PFA and PEEK tubing for precision dosing, with matching flanged/washer or ferrule connections. For doses up to 20 μL, rigid tubing downstream of the shut-off valve is recommended.
Plan valves for aspiration, dispensing and cleaning
Check bare-pump, pump/valve and driven configurations separately. Confirm EAV, EAD or EAVD when integration is needed; optional parts are not automatically included.
Flanged tube end with washer
Threaded fittingSupport washerFlanged tube end
The tube end is pre-flanged. The fitting presses the flange through a matching support washer against the sealing face of the flat-bottom port.
Dedicated tooling is needed to form the flange. Check flange integrity and the fit of washer and port during assembly.
Ferrule connection
Threaded fittingMatching ferruleUnflanged rigid tube
No pre-flanging is needed. Use matched fittings and ferrules for on-site assembly of rigid tubing. Tube outside diameter, ferrule and port must match as a set.
The ferrule occupies axial space; check hole depth separately. It is generally not intended for reuse after repeated disassembly.
Check the supplied configuration and disconnect power
Check capacity, head, ports, motor, sensor and valves against harness labels and drawings. Stop the instrument and disconnect power before mounting, wiring or changing tubing.
Secure the bracket and plan outlet routing
Brackets use 2 × M3 holes with 31.8 mm standard spacing or 42.8 mm wide spacing. Check this model’s mounting drawing, preferably orient the outlet upward, and leave space for fittings and wiring. Do not transmit tubing tension to the head.
Connect the fluid path and check flat-bottom seals
Check 1/4-28 UNF or M6 ports, hole depth, fittings and seals. Recommended torque for the corresponding plastic fittings is 0.25–0.30 N·m. If only one port is used, seal the other with a suitable plug. Do not replace flat-bottom seals with PTFE tape or thread sealant.
Connect the motor and sensor for the selected version
Use the motor diagram above to check windings and terminals, then the selected sensor diagram for supply and signal. Verify signal levels, pull-up/current-limiting circuits and the blocked-state polarity before powering on.
Set drive parameters and verify homing
Set phase current, microstepping and acceleration/deceleration for the supplied motor and driver. With a sensor, verify blocked state, direction and stopping clearance after triggering. Reinitializing homing after each test cycle is recommended according to the control sequence.
Prime, switch valves and remove bubbles
Prime with fluid compatible with all wetted materials. Repeat aspiration and dispensing to flush the chamber, valves and tubing, checking bubbles and leaks. Coordinate motion with the actual valve circuit; do not run dry for prolonged periods.
Compensate backlash, then validate the target dose
Set and verify backlash compensation in the program, then repeat aspiration/dispensing at the target volume and record collected amounts. For doses up to 20 μL, rigid tubing downstream of the shut-off valve is recommended. Also check bubbles, tubing elasticity and valve timing.
Validate the target volume in the actual circuit
After priming, homing and backlash compensation, repeatedly collect the same target volume and record results with a consistent measurement method.
- Fluid and operating conditions
- Fluid composition and concentration, temperature, back pressure or inlet vacuum.
- Fluid circuit and drive
- Tube material, inside diameter and length; valve timing; motor version, microstepping, speed, acceleration/deceleration and compensation.
- Individual collected results
- Target and actual collected volumes, measurement method, test count, and observations such as bubbles, trailing droplets or leaks.
- Comparison and retesting
- Compare mean deviation and variation under the same operating conditions and measurement method. Revalidate after changing fluid, tubing, valves or drive settings.
Record nominal steps, piston-stroke specifications and actual reagent delivery separately. Accept volume and repeatability at the target operating conditions.
Operation, shutdown maintenance and troubleshooting
- Saline or crystallizing fluids
- Avoid prolonged piston exposure to air and crystallization. Plan rinsing, protection and shutdown around the fluid and wetted materials; specify seal flushing if needed.
- Changing reagent or cleaning fluid
- The transparent head allows observation of filling and bubbles. PMMA (polymethyl methacrylate) is not resistant to alcohol or strong acids; both process and cleaning fluids must meet these material limits.
- Shutdown and storage
- Use a validated cleaning and storage procedure based on residual-fluid crystallization, corrosion and material compatibility. Confirm cleaner, concentration, duration and storage method for the actual fluid.
- Restart or after maintenance
- Check fittings, tubing and wiring, then refill and remove air. With a sensor, verify initialization first, followed by leaks, reversal compensation and target dose.
| Symptom | Check first |
|---|---|
| Delayed delivery or an undersized first dose | Check chamber/tubing bubbles, fitting seals and valve timing. Re-prime and remove air, then compare collected volumes. |
| Small-dose variation or error after reversal | Check backlash compensation, tubing downstream of the valve and steps for the target dose. Repeat measurements under identical conditions. |
| Motor vibration or intermittent motion | Check supplied motor, drive current, microstepping and acceleration/deceleration, along with tubing resistance and mechanical load. |
| Port leakage or head cracks | Stop operation and check fluid compatibility, flat-bottom seals and fitting torque. Retain the label, site photos and operating records, and contact service. |
Install and wire according to the supplied version. Contact technical support for modifications, disassembly, repairs or jamming.
Frequently Asked Questions
Nominal capacity is 100 μL with 2000 basic full-stroke steps, or 0.05 μL/step. This ratio converts motion commands. Validate the minimum reliable dose at the target volume, accounting for bubbles, backlash, valve operation and tubing elasticity.
Piston Pump Configured for Your Instrument
Share the target volume, fluid compatibility, port type, control method, installation space, and service-life requirements. The Foreach engineering team can help confirm the pump configuration and wetted materials.