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M2MD

non-contact, nanolitre to microlitre

For non-contact nL-dispensing, we offer the M2-MicroDispenser (M2MD) generation 6. It utilises variably fast volume displacement as a dispensing technique. The specified minimum dispense volume is 10 nL, and that can be increased to 5 µL. Variation of the ambient temperature limits the accuracy of the dispense volume to a c.v. of 5-10 %. Therefore, a temperature-controlled version that reduces it to 2 % for > 50 nL dispense volumes is available.

If only one solution must be dispensed, it can be advantageous to feed it from a reservoir attached to the dispenser. A so-called bulk-dispenser version of our M2MD, shown on the right, does exactly that. The solution to be dispensed is filled into a 20 mL glass vial, and if a small tube is preferred, it can be placed inside the vial.

nanolitre dispenser, low-volume dispensing, nanolitre dispensing

Key Features

  • single droplet volume 10 nl to 5 µl
  • up to 50 Hz dispensing frequency
  • Volume accuracy cv 2 % to 5 %
  • Bulk dispensing or Aspirate/Dispense types
  • Glass capillary or disposable plastic tip
  • quick change of capillary switch to tip

Functional Principle

The dispenser includes an ultra-fast solenoid valve, and two independent parameters - pressure and valve-opening time - determine the dispense volume. Small volumes (< 50 nL) are solely dispensed by fast volume displacement, and larger ones are dispensed by overlay of a pressure-driven flow. If the pressure is raised to dispense more viscous liquids, the valve opening time can be reduced to compensate for that, and if splashing occurs on the target surface, the liquid impact velocity can be reduced.

Dispensing Modes

  1. Stop-to-spot with Z-moves: The dispenser stops for each droplet deposition and moves up and down between consecutive positions to bypass possible obstacles. These movements cost time but can be necessary when dispensing onto specific locations of a non-planar, 3-dimensional target.
  2. Stop-to-spot, no Z-moves: Without the need to move the head up between consecutive positions, dispensing is much faster. This is always the case when dispensing onto planar targets.
  3. On-the-fly: The dispenser “flies” over the target and releases a droplet on defined positions during the flight. That way, up to 50 droplets per second can be deposited, each at its own specific coordinates.

Single-Droplet Volume Range

It covers the entire range from 10 nL to 1 µL:
Dispensing one larger droplet instead of multiple smaller droplets for nL-volumes reduces the risk of splashing (satellite drops).  Additionally, it is significantly faster, as the recommended maximum dispensing frequency is 20 Hz. Whether it can be increased to 50 Hz depends on the properties of the liquid.

Two kinds of dispensing tips

Two kinds of dispensing tip are available, and switching between them is simple. One is a thin glass capillary with a tapered end. The other is a conically shaped disposable plastic tip. Which of them is the preferred choice mostly depends on the application.  For that reason, we recommend having both to hand.

Custom Developments

3-Channel M2MD

Upon request, we build custom-tailored versions of our M2MD. This includes multiple channel configurations to increase throughput. The video shows a 3-channel M2MD at work. Other custom-tailored modifications include the extension of the maximum dispense volume, as well as a reduction of the minimum volume, from 10 to 5 nL

Clean samples – better results!

Washing is an essential step in surface assisted chemical analyses, chemical solid phase syntheses and basically in a lot of sample preparations. Salts and other buffer components as well as a dye for sample visualization can effectively be washed away right after immobilization of DNA, RNA, or protein molecules etc.

It is also possible to add reagents to samples in order to increase concentrations i.e. for MALDI-MS sample preparation.