An ergonomic design and performance evaluation of pipettes.

This paper describes the results of an investigation of the differences in performance, postures, strains on hand-arm-shoulder musculature, and subjective ratings of three pipettes (models A, B, and C). Both models A and B were pipettes available on the market. Model C was developed for this study of an ergonomically designed pipette. The gripping posture of the three models was distinct both in the anatomical and in the functional sense. Working with models A and B required a four-finger grasp with a thumb operated plunger. Model C required a finger-palmar power grip and the plunger was operated by the fingers. Performance evaluation of the different pipettes in different tasks indicated that using the proposed model C resulted in a 2-3% lower fault rate, a 10% shorter completion time, and the highest subjective ratings among the three. Postural analysis results indicated that when using model C, the shoulder was the least abducted, the wrist was the least extended, and the wrist was the least radially extended. Model C appeared to provide the greatest opportunity for delicate adjustments of posture in response to the activity of the skin receptors and reduced the strains on the upper body musculature, justifying the ergonomic input into the design.