Thermal Modulation and Instability of Newtonian Liquid Microjets
Nanotech 2005, (2005)Zusammenfassung
Liquid microjets are inherently unstable and can be
broken into droplets by various means including
modulation of pressure, velocity, and/or fluid properties. In
this presentation, we discuss the controlled breakup of
viscous microjets via thermal modulation of surface
tension. Such modulation has been implemented using
CMOS/MEMS technology by integrating resistive heating
elements around each orifice of a manifold as depicted in
Fig. 1. When the heating elements are electrically pulsed,
the thermal energy they produce penetrates the surface of
the microjet, and is carried downstream to produce a spatial
variation of surface tension along the length of the jet,
which ultimately causes breakup and drop formation (Figs.
1 and 2). Using this process, microfluidic devices have been
fabricated with thousands of individually modulated
microjets that can produce steady steams of picoliter-sized
droplets at kilohertz frequency rates 1. In this presentation
we review methods for analyzing such devices.