Micro-magnetofluidics offers a promising tool to regulate the drop formation process with versatile applications in engineering and biomedicine. In the present study, on-demand ferrofluid drop generation at a T-junction is investigated utilizing a magnetic pulse. Also, a novel method for ferrofluid droplet formation is introduced using a non-uniform Pulse-Width Modulation (PWM) magnetic field. A novel mechanism of drop generation named “beating regime” was seen for the first time in which the ferrofluid moves back and forth before the breakup. The effect of the magnetic induction, continuous phase flow rate, duty cycle, and applied frequency on the generation frequency and drop diameter was investigated under the PWM magnetic field and compared with those under the DC magnetic field. The results showed that greater values of drop diameter and generation frequency are obtained either when the magnetic induction and/or duty cycle increases or when the applied frequency decreases. The regime maps of ferrofluid droplet formation were presented for different magnetic Bond and Capillary numbers under both PWM and DC magnetic fields and compared with each other. Finally, a correlation was presented to estimate the dimensionless drop diameter on the basis of four nondimensionalized parameters, showing a 7.2 % average relative error.

微磁流体技术在工程和生物医学领域具有广泛的应用，为调节液滴形成过程提供了一种有前途的工具。在本研究中，利用磁脉冲研究了在T形结处按需产生的铁磁流体滴。此外，介绍了一种使用非均匀脉冲宽度调制（PWM）磁场形成铁磁流体液滴的新方法。首次发现了一种新的液滴产生机制，称为“跳动状态”，其中铁磁流体在破裂前来回运动。在PWM磁场下研究了磁感应，连续相流量，占空比和施加频率对产生频率和液滴直径的影响，并将其与DC磁场下的影响进行了比较。结果表明，当磁感应强度和/或占空比增大或施加频率减小时，可以获得更大的墨滴直径和产生频率值。给出了在PWM和DC磁场下不同磁键数和毛细管数下铁磁流体液滴形成的状态图，并进行了比较。最后，提出了一种相关性，可基于四个无量纲参数估算无量纲液滴直径，平均相对误差为7.2％。给出了在PWM和DC磁场下不同磁键数和毛细管数下铁磁流体液滴形成的状态图，并进行了比较。最后，提出了一种相关性，可基于四个无量纲参数估算无量纲液滴直径，平均相对误差为7.2％。给出了在PWM和DC磁场下不同磁键数和毛细管数下铁磁流体液滴形成的状态图，并进行了比较。最后，提出了一种相关性，可基于四个无量纲参数估算无量纲液滴直径，平均相对误差为7.2％。