Product Survey: Electronic Pipettes

Electronic Pipettes Come of Age
by Harald Zähringer, Labtimes 06/2015

The operation of early electronic pipette models was no fun at all. But things have greatly improved since their introduction in the middle of the nineteen eighties.

After thirty years of continuous evolution, electronic pipettes have lost their teething problems and finally entered into mainstream pipetting. They help life science researchers to increase productivity and may bring some relief to manual pipetting burdens.

It’s roughly 30 years since the companies Matrix Technology and Rainin independently introduced the first electronic micropipettes. The basic concept of the two electronic pipette pioneers was pretty simple and straightforward: just incorporate a microprocessor-controlled electronic motor into a typical manual micropipette and let them take over the tasks of the user’s thumb, i.e., pushing the piston up and down inside the pipette shaft. But the time wasn’t ready for electronic pipettes in the eighties. The instruments were too heavy and clumsy, the operation of the control unit placed on top of the pipetting grip a nightmare and the rechargeable batteries were always in agony and ran out quickly. On top of that, the instruments were very expensive.

Early attempts

No wonder then, that many researchers soon got frustrated with electronic pipettes and returned to their tried and tested manual pipettes. But the theoretical advantages of electronic pipettes were already in place for the early models, despite their practical issues: the microchip-controlled, up and down motion of the plunger is more accurate and precise than thumb-driven movements; the risk of repetitive strain injuries (RSI) with manual pipettes due to high plunger forces and the awkward adjusting of volume wheels with thumb and fingers is strongly reduced; and last but not least, electronic pipettes offer a lot more pipetting and dispensing options than their manual cousins.

Hence, Matrix Technologies and Rainin continued to improve their models, initially joined by the Finnish company, Biohit, in the early nineties, which developed a smaller electronic pipette with a reduced weight. But it took another ten years until the first major players such as Eppendorf and Gilson stepped into the electronic pipetting market and introduced competitive models that passed the reality check in life science laboratories. Today, most pipetting companies offer their own series of electronic pipettes. Considerable advantages in battery technology and consumer electronics over the last decade have solved the problems associated with early models, except for the slightly higher weight compared to manual pipettes.

Powerful batteries

Modern electronic pipettes come with rechargeable Li-Ion (Li-Polymer) or NiMH batteries. Li-Ion batteries are known for their high energy density and lack of the so called memory effect that pesters NiCd and NiMH batteries. Due to the memory effect, NiCd and NiMH batteries gradually lose their capacity, if they are repeatedly partially discharged before recharging. Li-Ion batteries in electronic pipettes have stored enough energy after a few minutes of charging to support several hours of pipetting and are usually fully charged after two hours. Most electronic pipettes may be charged with wall power supplies allowing operation during charging, on charge stands or via USB cables.

The arrangement of the operation buttons and the location and format of the display are the most crucial details of electronic pipettes, with an immediate impact on ergonomics and usability. A closer look at theses details and a thorough practice test in the laboratory should be mandatory before buying an electronic pipette.

Design evolution

The most popular design of current operation panels follows the original idea of Matrix Technologies and Rainin, to implement an angular control panel and a display on top of a classical pipette grip. However, the wedge-shaped, sharp-edged control units of the early prototypes, with hard to handle square operation buttons, have turned into soft-edged, gently sloped extensions of the pipetting grip with embedded buttons, joysticks or touch wheels as well as LED screens for a smooth operation of the pipette with one hand.

There are, however, subtle differences between current individual electronic pipettes, which may affect their handling and ergonomics. Researchers and technicians, accustomed to pressing clearly-defined control buttons to handle a pipette, may shy away from models with touch wheels or joysticks, which navigate several functions by a simple touch of the finger. Touch wheels are a great feature – as long as the user doesn’t touch the wheel accidentally during operation and thus mix up the settings of his pipetting menu. Or even worse, mistakenly pushes either the aspirate or the dispensing button – both of which are often embedded into the joysticks or touch-wheels or placed pretty close to them. Hence, electronic pipettes with “old fashioned” mechanical pipetting menu selection dials or thumbwheels, which are clearly separated from the control buttons, are not the worst idea.

Standing on its own

Most electronic pipettes are based on an axial design with a slim cylindrical shaft, a round or oval grip and an angular extension of the grip with embedded keypad and display. There are, however, two exceptions to this rule: the ski boot design of former Matrix Technologies (now Thermo Scientific) multichannel pipettes and the unusual shape of Vista Labs Ovation model. The ski boot pipette is basically a classic multichannel pipette with a ninety degree, twisted pipette shaft orientated in parallel to the control pad, to ease pipette operation.

The non-axial shape of the Ovation is way more radical and completely ignores the axial design of traditional micropipettes. The shaft of the Ovation is mounted crossways to the grip head (instead of axial at the grip end) with a downward angle of about 20 degrees. The non-axial orientation of the pipetting shaft has two consequences: firstly, the pipette stands on its own on the bench without the need of a pipetting stand and, secondly, it may be operated with a neutral wrist and shoulder position, avoiding stress to muscles and tendons. Similar to the pipette shaft, the control pad and the small display of the Ovation are also orientated “upside down” at the lower end of the grip, which may be unfamiliar to new users.

No more banging into tip boxes

For a long time, tip-loading and ejection was a weak point of both manual and electronic pipettes. Researchers hammering their pipettes into tip boxes to assure a firm attachment between tip and pipette shaft was a common picture in many life science labs. Releasing the friction-locked tips from the shaft was no fun either and took reasonably high tip ejection forces. Hence, most manufacturers switched from friction-locked tips with conical-tipped shafts to form-locked tips, which clip into specially designed pipette shafts. The tips are usually sealed with O-rings integrated into the lower end of the pipette shaft. Form-locked tips considerably reduce attachment and tip ejection forces as well as the risk of tips leaking or dropping off.

Vendors of electronic pipettes usually offer free evaluation models to check out the handling and ergonomics of their instruments in a real lab situation before buying. The tables on the next pages may help you to shortlist your favoured evaluation models.

First published in Labtimes 06/2015. We give no guarantee and assume no liability for article and PDF-download.

Table of Products as PDF-download: pdficon Formatted for Printout