Development and optimization of a precision and reliable particle dispensing system integrated with a pendulum motion dispensing module

Abstract This study presents a novel approach to enhancing microparticle dispersion and ejection performance by utilizing a pendulum motion of a particle reservoir. Owing to their tendency to sediment in suspension, microparticles pose significant challenges in achieving consistent and repeatable ejections, often leading to nozzle clogging. To overcome these challenges, a three-axis automated particle dispensing system integrated with a rotational dispensing module was developed. The pendulum motions of the dispensing module were investigated to assess their impact on particle dispersion, including 90-degree, 180-degree, and 360-degree swings. The 360-degree pendulum motion sustained particle dispersion, leading to the consistent and reliable ejection of particles during continuous droplet ejection. Moreover, we evaluated a novel particle dispensing system, including the effects of particle suspension density and dispensing parameters on the ejection performance and dead volume of minute particle samples. Stable particle dispensing was achieved, with a CV below 7%, even at high concentrations (14% w/v). The number of ejected particles exhibited a linear relationship ( R 2 = 99%) with suspension densities ranging from 1%–14% w/v. Furthermore, dispensing parameters such as the amplitude and duration of the applied pressure showed a linear correlation with both the number of ejected particles and the volume of ejected droplets ( R 2 = 99%). The dead volume was 2 μ l, representing 10% of the 20 μ l small sample used. These results demonstrate the flexibility of the system in maintaining a high performance across a range of operational conditions. The findings highlight the potential of this rotational approach for enhancing the reliability and accuracy of particle dispensing in microfluidic applications.