The good deformability and electrical conductivity of the liquid
metal-based soft robot enable its application as a miniature electronic
switch, which can be remotely controlled. A circuit comprising 3 LED
arrays that depict the letters “S”, “Z”, and “U” and copper foil
as interconnects in a water bath (with 1 wt% Tween 80). Each of the LED
arrays has its own open circuit, as depicted in Figure 6a (Movie S5).
The copper electrodes in the water bath do not touch each other,
resulting in an open circuit. Here, the liquid metal-based soft robot is
employed as a controllable switch; the deformation and shape morphing
are controlled by a magnet. Initially, all circuits were open and the
LED arrays remained dark. After placing a liquid metal-based soft robot
in the middle of the electrodes and actuating it by a bar magnet, one of
the three open circuits (the one connected to the “S” LED array) was
closed, resulting in the light-up of the “S“ LED array, as shown in
Figure 6b. Similarly, other LED arrays can be selectively switched on
and off again. Furthermore, one single soft robot could be deformed
circular, as described 3e and f, in order to close all three circuits,
resulting in light up of all three LED arrays, which spell together the
acronym SZU (see Figure 6c). Importantly, the on-demand deformation of
the liquid metal-based soft robot is reversible and other
interconnection patterns can quickly be achieved. Furthermore, the soft
robot can be retrieved after usage and reused for other applications.
These results demonstrate the capability of the liquid metal-based soft
robots and their potential in applications like dynamic and recyclable
switches for complex circuits. Compared with a traditional miniature
electronic switch, which may require a complex switch design or multiple
switches to control the complicated circuit, the liquid metal droplet
robots enable simple remote control of complex circuits in a
reconfigurable manner, which effectively simplifies the circuit layout.