Lightweight, reliable and ergonomic: Eppendorf's Research plus pipettes
“best in its class” for user-friendly features
Eppendorf Application Note197.
Authors: Kornelia Ewald, Eppendorf AG, Hamburg, Germany and Michael Schicke, Eppendorf Liquid Handling GmbH, Hamburg, Germany
Gratefully reproduced from Eppendorf BioNews Issue 33
In todayâ€™s research environment, attention on pipettes no longer focuses exclusively on precision and accuracy; instead, user-friendly operating features, which reduce strain during pipetting, have moved into the foreground. Therefore, ergonomics plays an important role for the user. Primarily mentioned aspects are the weight of the pipette and the forces required during use. Included in the handling force are, among others, the force required for attachment and securing as well as ejection of the pipette tip. The new mechanical pipettes of the pipette family Eppendorf Research plus[A][B][C] have demonstrated optimal performance in all those areas.
Continuous new demands on pipettes and related dispensing to manage larger numbers of samples of reduced volume, devices have given rise to a number of different dispensing increasingly comfortable pipetting and dispensing systems systems. While these instruments had initially been devised have evolved. The new mechanical piston-stroke pipettes for specific applications, they are now being used in a by Eppendorf, Research plus[A][B][C], are equipped with a number variety of different areas. Due to the trend towards having of remarkable patented functions.
Spring-loaded tip cone
The pipettes of this new family of pipettes are based on a novel principle, a so-called tip-cone [Fig.1]. During attachment and securing of the pipette tip onto the cone the extra force exerted is compensated by the spring loaded tip cone. This signals the tight fit of the tip. Thus, on the one hand, a significantly decreased force is needed to achieve optimal fit, while on the other hand this limitation of force will facilitate the subsequent tip ejection. In addition,
the spring loading of multichannel pipettes yields a significantly better tip fit as well as optimized tip alignment, thus eliminating the need for manual adjustment of individual tips. An additional effect of spring loading is the prevention of the so-called â€śslip stickâ€ť, a backwards movement of the piston following longer periods of inactivity, as the pipette piston is automatically moved during the attachment of the tip. Thus, extra force during the first stroke of the piston is no longer necessary.
Fig. 1: Spring loading of the tip cone (1) improves the fit of the pipette tip during attachment (2).
Fig. 2: Pipette without spring loading
Forces and weight
In comparison with several competitorsâ€™ pipettes, the pipetting forces and extra stroke forces of the Research plus pipettes were determined [Fig. 3 and 4].
Furthermore, the ejection force was measured for each pipettes with the assigned pipette tip at an obtainable attachement force
of 50 N [Fig. 5]. With the Research plus, this attachement force (50 N) cannot be reached due to the spring loaded tip cone.
In comparison with various competitorsâ€™ pipettes, the Research plus pipette is one of the lightest pipettes available on the
market [Fig. 6].
Novel piston material
In order to reduce the handling forces as well as the weight of the Research plus pipettes, high quality synthetic materials
were used in the production of pipette pistons of the 20 ÎĽL (yellow) to 10 mL volume range. The material PPS (polyphenylene
sulfide, Fortron) was used for the cylinder, the piston rod is made from PEI (polyetherimide), and the washer is made
from EPDM (ethylene-propylene-diene-rubber). Through the use of these tried and tested materials, in combination with
the novel method of production of the pipette piston, an extremely easy forward and backward sliding of the piston was
achieved. All synthetic materials used were subjected to chemical resistance testing over an extended period of time
(100,000 strokes) using different substances, such as ethanol, acetone, concentrated hydrochloric acid and nitric acid.
During this test phase, all plastics demonstrated very good chemical resistance. Furthermore, they showed high temperature
resistance. The pistons of pipettes of the volume range 0.1â€“20 ÎĽL (gray) are made from corrosion-free vanadium steel,
as in previous generations.
Multichannel pipettes with 4 or 6 channels, respectively
Fewer than 8 or 12 channels of the multichannel pipettes, respectively, can be used. In order to adapt the pipette cones
to the varying distances between wells of a 24- or 384-well microtiter plate, pistons or tip cones can be removed and thus
inactivated. Even filling of tubes in racks is easily possible. The procedure for channel reduction is described in Application Note No. 198.
In the context of the reliability test, the following tests listed below were performed with the Research plus pipettes:
100,000 x tip attachment
100,000 x tip ejection strokes
200,000 x strokes including excess stroke
50,000 x volume adjustment
250 x pulling off of the ejection case
200 x detachment and re-attachment of the lower part
175 autoclave cycles (121 Â°C, 1 bar, 20 min.)
The number of respective tests chosen corresponds to an average 5 year use of the pipette. Additional tests included
change of the adjustment, falling tests and gravimetric tests according to EN ISO 8655.The results showed that the new
pipette family by Eppendorf meets testing requirements in all capacities and did not show any signs of damage or
impairment following testing.
In the meantime, the function as a precision measuring device is only one demand placed upon a pipette. In the future,
other additional features of a pipette will be important factors in deciding whether a certain pipette is suitable for specific
The Research plus pipette [A][B][C] meets present and future requirements, such as reduction of handling force and weight, as well
as spring loading of the work cone in order to achieve reduction of tip attachment force in a unique fashion. In summary,
its design and ergonomics are definitely forward-looking.