An investigation of hand forces and postures for using selected mechanical pipettes

Abstract

The present study evaluated thumb, hand forces, wrist, forearm and shoulder postures used for pipetting with three selected mechanical pipettes. Twelve pipette users in a large university health system participated in pipetting simulation in their own laboratories to investigate the effects of pipette type, body posture (standing/seated), sample volume (200/1000 μL) and pipetting task on the physical risk factors. The thumb and hand forces were measured with 19 Flexiforce™ sensors. Wrist and forearm postures were measured with an electrogoniometer and a torsiometer, respectively. Humeral elevation as shoulder postural stress was assessed by observations from videos recorded during pipetting simulation. The study results showed several advantages of using the non-axial pipette over the traditional axial ones. The non-axial pipette was associated with approximately 2–6 times less thumb and hand force than the traditional axial pipettes. In addition, there were approximately 20–30% reductions in ulnar deviation and 30–70% reductions in humeral elevation to operate the non-axial pipette for most of the pipetting actions. One disadvantage of using the non-axial pipette appears to be increased forearm pronation by approximately 100–150% for the entire pipetting cycle, as compared to the axial pipettes. The results of the study may provide useful information regarding design of pipettes for reducing physical risk factors associated with pipetting. Relevance to industry This paper demonstrated hand forces and postures for common pipetting tasks with selected mechanical pipettes. The hand force and postural data for using axial and non-axial pipettes may provide key information for hand injury prevention due to pipetting in the industry.