Title: Reconfigurable Liquid Metal Circuits by Laplace Pressure
Shaping
5
FIG. S1. Simulated data for dipole in Fig. 5.
Regarding precision dosing, frequently during experiments the liquid metal was over- or under-dosed
with respect to the volume of the trench to be filled. Certainly, there are more accurate dosing approaches than
the manual pipetting used in this work. However, there are also other mechanisms to automatically achieve
accurate dosing volume using self-adaptive trenches. One such method is shown in Fig. S2, and operates as
follows: (a) at no vacuum a liquid metal droplet starts in one reservoir location; (b) vacuum is applied and liquid
fills all trenches; (c) vacuum is released and trench dewetting occurs first at the pinch-off positions; (d) liquid
metals localize and auto-dose at correct volumes for each leg of the trench. The pinch-off points can effectively
split the fluid using one of two mechanisms: if the vacuum releases extremely fast the pinch-off points could
cause dominant selection of a Rayleigh–Taylor instability;33 or, with slower vacuum release, the pinch-off
points simply impart a higher Laplace pressure which dewets from the trench first (Eq. 1). Either mechanism
achieves the same end result. Also, any excess liquid metal can be removed and a single leg of the trench
actuated. The removal of excess liquid metal can be achieved by movement to an adjacent reservoir with lower
Laplace pressure.
FIG. S2. Self-adaptive dosing of liquid metal into a 50 um trench: (a) liquid metal in starts reservoir; (b) vacuum applied
and liquid fills all trenches; (c) release vacuum and trench de-wetting occurs first at the pinch-off positions; (d) liquid metals
localized and auto-dosed at correct volumes for each trench leg.
33
P. D. Rack, Y. Guan, J. D. Fowlkes, A. V. Melechko, and M. L. Simpson, Appl. Phys. Lett. 92(22), 223108
(2008).