Abstract: In order to overcome the difficulty in the picoliter ( pL ) -class trace distribution and the dispensing in narrow spaces of high-viscosity fluid,the factors affecting the pL-class dispensing performance of transfer printing were theoretically analyzed,and some experiments were carried out to explore the influences of fluid viscosity,dispensing velocity,liquid transfer needle s holding time and fluid concave on dispensing performance.Finally,pLclass dispensing of high-viscosity ( 5Pa·s and 30Pa·s) fluid in narrow seam ( 0. 5mm × 20mm) was implemented.The results show that,at low dispensing velocity,the dispensing volume increases as fluid viscosity increases but keeps almost unchanged with the holding time of liquid transfer needle,while the contrary occurs at high dispensing velocity; and that the transfer printing liquid distribution method can effectively inhibit the formation of fluid concave and reduce random factors-induced impact with well-matched dispensing parameters.Thus,the pL-class dispensing and packing in a narrow seam of high-viscosity fluid can be successfully implemented with high accuracy and good repetitiveness.

Key words: pL-class trace dispensing, performance analysis, dispensing velocity, fluid viscosity, holding time, dispensing in narrow seam