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A liquid-metal intelligent reflecting surface (IRS) unit cell is presented, using hybrid electrocapillary actuation to enable reconfigurability. Elongation of the liquid metal by up to 4 mm is experimentally demonstrated, corresponding to a ~ 180° reflection phase shift between two unit-cell states. Simulation of a 7 × 6 IRS array based on these two unit-cell states results in non-specular reflected signals at 4.85 GHz that are indicative of IRS functionality. 

Controllable deformation of liquid metal by electrocapillary actuation (ECA) is empirically characterized in fluidic channels at the sub-millimeter-length scale. In 100-µm-deep channels of varying widths, the Galinstan liquid metal could move at velocities of more than 40 mm/s. The liquid metal could extend more than 2.5 mm into the channels at an electrocapillary actuation voltage of 3 V DC. The dynamic behavior of the liquid metal as it moves in the microchannels is described. These results are useful for designing microsystems that use liquid metal as a functional material. 

Abstract Recent progress in the understanding of the behavior of the interference channel has led to valuable insights: first, discrete signaling has been discovered to have tangible benefits in the presence of interference, especially when one does not wish to decode the interfering signal, i.e., the interference is treated as noise, and second, the capacity of the interference channel as a function of the interference link gains is now understood to be highly irregular, i.e., non-monotonic and discontinuous. This work addresses these two issues in an integrated and interdisciplinary manner: it utilizes discrete signaling to approach the capacity of the interference channel by developing lower bounds on the mutual information under discrete modulation and treating interference as noise, subject to an outage set, and addresses the issue of sensitivity to link gains with a liquid metal reconfigurable antenna to avoid the aforementioned outage sets. Simulations illustrate the effectiveness of our approach. 

Liquid metals such as gallium alloys have a unique potential to enable fully reconfigurable RF electronics. One of the major concerns for liquid-metal electronics is their interaction with solid-metal contacts, which results in unwanted changes to electrical performance and delamination of solid-metal contacts due to atomic diffusion of gallium at the liquid/solid interface. In this paper, we present a solution to this problem through way of liquid-metal/liquid-metal RF connections by implementing Laplace barriers, which control fluid flow and position via pressure-sensitive thresholds to facilitate physical movement of the fluids within the channels. We demonstrate RF switching within the channel systems by fabricating, testing, and modeling a reconfigurable RF microstrip transmission line with integrated Laplace barriers which operates between 0.5–5 GHz. This approach opens the potential for future all-liquid reconfigurable RF electronic circuits where physical connections between solid and liquid metals are minimized or possibly eliminated altogether.