Microarray
Spotting Technology

Microarray Spotting Technology
Microdispenser

At M2-Automation, we offer both non-contact and contact microarray dispensers. Would you like to know the difference between them?

Our non-contact micro-dispensers eject the liquid as individual droplets or short jets, which then fly towards the target (non-contact liquid handling). These dispensers can be classified by the minimum ejection (droplet) volume they can eject as well as underlying functional principle. Our piezo-driven microdispenser (PDMDs) rely on ultrafast volume displacement and start picoliter. Our flow-based microdispensers start in the low nanoliter volume range and include solenoid valve-driven microdispensers (SDMDs) as well as version 2 of our proprietary M2-microdispenser product line. Version 3 utilizes fast volume displacement instead enabling very high volume accuracy. Contact-based microdispensers utilize pins that are dipped into the source liquid and then brought in contact with the target surface. They can be classified into three groups: Blunt-end pins, split pins and capillary pins. The liquid is transferred as a hanging droplet, which can be replaced from a reservoir in the case of split or capillary pins.

Read on to learn more about all the subtleties of M2’s first-rate microdispensing technology.

non-contact microdispenser, picoliter and nanoliter dispenser, picoliter microarray dispenser, microarray printing technology

Non-Contact Microdispensing

The sample solution is transferred through the air towards the target as an individual small droplet, series thereof or a liquid jet. The main advantage of non-contact microarray spotting or printing of microdroplets is that the sample transfer does not depend on the properties of the target surface.


The microdispenser does not touch the target - no damage, no contamination by the target and perfect reproducibility of sample transfer is given. The microdispenser and the properties of the sample liquid determine the spotting volume. Target surface structure and surface tension have no influence on the deposited volume. The wetted area on the target (spot size) is determined by the surface tension of both, the liquid and the target surface (e.g., hydrophobic versus hydrophilic). If up to a few hundred different samples need to be printed onto many targets, non-contact microarray spotting is the method of choice.

PDMD – Piezo Driven MicroDispenser

A non-contact microdispenser for picoliter volume applications (20pL and more)

Functional Principle: Ultrafast liquid displacement – microdroplet generation - caused by a short contraction of a cylindrical piezo actuator bonded to a thin glass capillary.

  • Application modes: Aspirate and dispense, dispense from reservoir
  • Ultrafast operation: 1-1000 droplets/s
  • High volume accuracy: c.v. = 1.5-2%
  • Large droplet volume range for each dispenser: 400-500% (e.g., 40-200pL)
  • Different droplet volume ranges available: 20-80pL, 35-150pL, 60-300pL
  • Custom tailored droplet volume ranges are available on request
  • Precise volume control: in 1pL steps
  • Precise droplet ejection velocity control: 0.5 - 4m/s in 0.1m/s steps
  • Dynamic viscosity range: 0.5-10mPas
  • Chemically extremely inert and biologically compatible: Sample Solutions come only in contact with a thin borosilicate glass capillary
  • M2 non-contact piezo microdispenser glass tip

M2MD02 – M2-MicroDispenser version 02

A non-contact micro-dispenser for highly flexible nano- and microliter volume applications (10nL and more)

Functional Principle: Flow-based solenoid valve microdispensing (see Volume displacement versus flow-based microdispensing) combined with a shock wave generator that actively supports the ejection of small droplets by a positive and following negative pressure wave. Small volumes are dispensed as individual droplets (10-50nL), larger once as liquid jets.

  • Application modes: Aspirate and dispense, dispense from reservoir
  • Very fast Operation: Up to 100 droplets per second (1-100Hz)
  • Moderate volume accuracy: c.v. 3-20% depending on ambient temperature drifts
  • Very large single ejection volume range: > 100,000% (e.g. 10-10,0000nL)
  • Each dispenser can dispense the entire single-ejection volume range
  • Precise volume control: in nanoliter steps
  • Dynamic viscosity range: 0.5-20mPas (for a maximum pressure difference of 1bar)


Special features:

  • Exchangeable dispensing tips and tip holder (different formats)
  • Compatible with low-cost 0.5-10μL disposable pipetting tips as dispensing tips for 50-nL+ volume applications
  • Compatible with different tip materials (e.g., glass, plastic, ceramic, metal)
  • more info on request (info@m2-automation)
  • M2 Nano-Liter-Dispenser

M2MD03 – M2-MicroDispenser version 03

A unique non-contact microdispenser developed by M2-Automation for highly accurate nanoliter volume applications

Functional Principle: Fast volume displacement induced by a unique technology developed by M2-Automation. Small volumes are dispensed as individual droplets (10-50nL), larger once as liquid jets.

  • Application modes: Aspirate and dispense, dispense from reservoir
  • Fast Operation: Up to 20 droplets per second (1-20Hz)
  • High volume accuracy: c.v. 1.5-2%
  • Large droplet volume range: 500% (e.g. 10-50nL or 100-500nL)
  • Different droplet volume ranges available: 10-50nL, 50-250nL or 100-500nL
  • Custom tailored droplet volume ranges are available on request
  • Precise volume control: in nL steps
  • Dynamic viscosity range: 0.5-20 mPas


Special features:

  • Exchangeable dispensing tips and tip holder (different formats)
  • Compatible with low-cost 0.5-10 µL disposable pipetting tips as dispensing tips for the entire droplet volume range (10 nL+)
  • Compatible with different tip materials (e.g., glass, plastic, ceramic, metal)
  • Cartridge version for flexible dispense-from-reservoir applications. More info on request (info@m2-automation)
  • M2 non-contact nanoliter microdispenser disposable plastic tip

SDMD – Solenoid valve Driven MicroDispenser

A non-contact microdispenser for highly flexible nano- and microliter volume applications.

Functional Principle: Flow-based solenoid valve dispenser. The flow is driven by a constant pressure difference and the opening time of a small solenoid valve determines the dispense volume. Small volumes are dispensed as individual droplets (10-50nL), larger once as liquid jets.

  • Application modes: Aspirate and dispense, dispense from reservoir
  • Very fast Operation: Up to 250 droplets per second (1-250Hz)
  • Moderate volume accuracy: c.v. 5-20% depending on ambient temperature drifts
  • Very large single ejection volume range: > 100,000% (e.g. 10-10,0000nL)
  • Each dispenser can dispense the entire single-ejection volume range
  • Precise volume control: in nanoliter steps
  • Dynamic viscosity range: 0.5-10mPas (for a maximum pressure difference of 1 bar)


Special features:

  • The dispensing tip is a stainless steel capillary. It is part of the microdispenser and cannot be replaced
  • SDMDS are, compared to M2MDs a lot smaller and lighter, which suggests their use in applications where size and weight are very critical parameters

Volume displacement versus flow-based microdispensing

An advantage of non-contact flow-based microdispensing is the highly flexible volume control by pulse-width modulation. A disadvantage is the need for volume calibration as the flow rate, and thereby the dispensed volume, depends on the dynamic.
More info on request (info@m2-automation)

Microarray
Spotting Technology

Droplet in droplet dispensing

Contact

Contact Microdispensing

The sample solution is transferred from a pin to the target surface by a short contact. This can be a small droplet hanging at the blunt end of a solid pin, flowing out of a small gap (split pin) or one end of a capillary (capillary pin). In any case contact to a target surface is required for sample transfer.


The main advantage of contact-based microarray spotting or microarraying is the ease of parallel spotting enabling high sample throughput. If a large number of sample solutions (e.g., thousands) is to be spotted onto only substrates (e.g., DNA slides, Labon a chip strucurers, Biochips, membranes etc.), contact-based array spotting using many pins in parallel is the method of choice.

PinDMD - Pin Driven MicroDispenser

Blunt end pins - the most simple microarraying pins

Functional Principle: The pins are dipped into sample solution. When pulled out a hanging droplet of it remains at the blunt end of the pin. During contact with the target surface a part of it is transferred (remains on the surface). How much depends on the surface tension of the liquid and the involved surfaces (pin + target).

  • Application modes: Wet and spot
  • Spotting uniformity: Can be good but requires very homogeneous target surfaces
  • Volume accuracy: Depends on solvent evaporation during transfer as well as the wettability of the target surface. Better than with split pins and lower than with capillary pins
  • Volume range: The diameter of the blunt end of tip determines the transfer volume
  • Accessible range: low nanoliter range
  • Dynamic viscosity range: No general limit, significantly higher than for split and capillary pins

Split pins – microarraying pins with a split end

Functional Principle: The split end provides a liquid reservoir that is filled by capillary force when the tip is immerged in sample solution. During contact with the target surface a fraction of the liquid is transferred. How much depends on the surface tension of the liquid and the involved surfaces (pin + target).

  • Application modes: Fill and spot several times (10-30 times)
  • Spotting uniformity: Worse than with blunt end or capillary pins. Requires careful tuning and very homogeneous target surfaces
  • Volume accuracy: Moderate and worse than with blunt end or capillary pins. Depends on many parameters (solvent evaporation, contact time, surface tension etc.)
  • Volume range: low nanoliter range
  • Dynamic viscosity range: No general limit, higher than for capillary pins and lower than for blunt end pins

Capillary pins

Functional principle: The capillary provides the liquid reservoir, which is filled by capillary force when the pin is immerged in sample solution. In contrast to split pins the aspirated liquid is protected against solvent loss by evaporation enabling up to several hundred sample depositions after sample aspiration. Aliquots as small as 300 pL can be spotted.

  • Application modes: Aspirate and spot many times (> 100 times)
  • Spotting uniformity: Usually good, significantly better than with split pins
  • Volume accuracy: depends on properties of the sample solution as well as the target surface (surface tension). Better than with blunt end or split pins
  • Volume range: In the first place determined by the tip diameter (available: 80, 100, 140, 200, 300, 350, 500 and 700 µm). Water on glass: 300pL and 7nL for i.d. 80 and 700 µm. Fine tuning of the spotting volume can be achieved by variation of pin contact time and the velocity at which the pin moves towards and away from the target surface
  • Dynamic viscosity range: Depending on tip diameter, no general limit, lower than for split or blunt end pins


More info on request (info@m2-automation)

  • microarray solid pins mounted at microarray contact printer iSIX

Your microdispenser or
3rd party micro dispenser devices

M2-Automation offers custom-tailored solutions and is not limited to the use of its own micro-dispensers. Other companies on the market, for instance, offer non-contact microdispensing solutions for very viscous liquids and pastes (100-100.000mPas), which we do not have and might be necessary to meet your demands. Or you have developed your own micro-dispenser and would like to get it implement in an M2-Automation microarray printing instrument. Another possible option is the implementation of our microdispensers or other components as well as software in your automation solution.

M2-Automation Technology & Innovation

Call Us at +49 30 856 11 939 0 and check out our great features.

Contact

Related Products