Micro-droplet ejection is a liquid dispensing technology that has potential applications in many fields. Specifically, pneumatic ejection is actuated by a solenoid valve, which is set to ‘conduction’ state for a brief period of time Δt. High pressure gas of P ₀ enters the liquid reservoir, then releases through a venting tube, creating a oscillating pressure waveform P(t), forcing the liquid out through a tiny nozzle to form a micro-droplet. For each actuation, P(t) is acquired by a high-speed pressure sensor, and the ejection state is obtained by high-speed photography and image processing methods. Some issues for the design of pneumatic micro-droplet ejector are discussed. For simulation of P(t), it is proposed within an electro-acoustic analogy picture that the acoustic resistance of the venting tube is mainly due to viscous effect and may vary with time during the whole ejection process. Based on this assumption, the calculated P(t) is more consistent with the actual measurement. Experimentally, the droplet ejection process for different length of venting tube is studied. With P ₀ and Δt set, by increasing the venting tube length L, both the peak value P _MAX1 and duration of the first positive pressure period increase, and more droplets are ejected from a single actuation. By setting different P ₀, P _MAX1 for different L is tuned to an identical and appropriate value, so that single droplet is ejected due to the first positive pressure period. However, with the increase of L, the peak value of the second positive pressure period P _MAX2 increases. There is a certain probability that another droplet is ejected. It is realized that the increase of L can reduce gas consumption, but the multiple ejection is a drawback that should be considered in the design of pneumatic ejection system.

微滴喷射是一种液体分配技术，在许多领域都有潜在的应用。具体地，由电磁阀致动气动喷射，该电磁阀在短时间段Δt内被设置为“传导”状态。P _0的高压气体进入储液罐，然后通过排气管释放，产生振荡压力波形P（t），迫使液体通过微小的喷嘴流出，形成微滴。对于每次驱动，P（t通过高速压力传感器获取），通过高速摄影和图像处理方法获得喷射状态。讨论了气动微滴喷射器设计中的一些问题。为了模拟P（t），建议在电声图片中将排气管的声阻主要归因于粘性效应，并且在整个喷射过程中可能会随时间变化。基于此假设，计算出的P（t）与实际测量值更加一致。实验研究了不同长度排气管的液滴喷射过程。与P ₀和Δ吨通过增大排气管长度L，峰值P _MAX1和第一正压周期的持续时间都增加，并且通过一次致动喷射更多的液滴。通过设置不同的P ₀，将用于不同L的P _MAX1调整为相同且适当的值，从而由于第一正压周期而喷射出单个液滴。但是，随着L的增加，第二正压期间P _MAX2的峰值增加。很有可能还会有另一滴液滴喷出。认识到L的增加 可以减少气体消耗，但是多次喷射是气动喷射系统设计中应考虑的一个缺点。