At M2-Automation, we offer both non-contact and contact microarray dispensers. Our non-contact dispensers eject the liquid as individual droplets or short jets, which then fly towards the target. Contact-based micro dispensers utilize pins that are dipped into the source liquid and then brought in contact with the target surface.
Non-contact dispensers can be classified by the minimum ejection (droplet) volume they can eject as well as underlying functional principle. Our piezo-driven micro dispenser (PDMD) relies on ultrafast volume displacement and start picoliter. Our flow-based micro dispensers start in the low nanoliter volume range and include solenoid valve-driven micro dispensers (SDMDs) as well as version 2 of our proprietary M2-micro dispenser (M2MD) product line. Version 3 utilizes fast volume displacement instead enabling very high volume accuracy. Version 4 combines a flow-based and a volume displacement technique facilitating the advantages of both techniques while avoiding their disadvantages.
The newest addition to the dispenser family is the Pin-Driven Micro Dispenser (PinDMD), which transfers the sample using either split-, blunt-end-, or 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.
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.
Functional Principle: Ultrafast liquid displacement – microdroplet generation - caused by a short contraction of a cylindrical piezo actuator bonded to a thin glass capillary.
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.
Functional Principle: Comparison of flow-based and a volume displacement technique facilitating the advantages of both techniques while avoiding their disadvantages. Small volumes are dispensed as individual droplets (10-50nL), larger once as liquid jets.
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.
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)
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.
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).
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).
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.
More info on request (info@m2-automation)
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.