Smart Fluid Systems: The Advent of Autonomous Liquid Robotics

Abstract

Organic, inorganic or hybrid devices in the liquid state, kept in a fixed volume by surface tension or by a confining membrane that protects them from a harsh environment, could be used as biologically inspired autonomous robotic systems with unique capabilities. They could change shape according to a specific exogenous command or by means of a fully integrated adaptive system, and provide an innovative solution for many future applications, such as space exploration in extreme or otherwise challenging environments, post‐disaster search and rescue in ground applications, compliant wearable devices, and even in the medical field for in vivo applications. This perspective provides an initial assessment of existing capabilities that could be leveraged to pursue the topic of “Smart Fluid Systems” or “Liquid Engineered Systems”.

Liquid Metal–Based Soft Microfluidics

“…Soft robots, distinguished from the conventional robotics, not only show the robotic features for complete targeted tasks, but also offer intrinsic adaptability and reconfigurability to their surroundings for easier actuation and function . LM, either in the form of droplet or in the form of doping materials, can serve as the key component for the actuation of the soft‐robotic machines via energy conversion processes that transform various kinds of energy, such as magnetic energy, electric energy, thermal energy, light energy and chemical energy to the kinetic energy . The LM‐based robots show their broad applications in the on‐demand control and switching of electronic circuits, pumping and mixing of the fluids, biomedical therapeutics with targeted delivery capabilities, and so forth.…”

Enhanced dielectric performance and energy storage of PVDF‐HFP‐based composites induced by surface charged Al2O3

“…Most recently, ferroelectric polymers, such as PVDF and its copolymers, have become research focuses owing to their inherent advantages of high breakdown strength, better thermal stability, and facile process‐ability. With the rapid development and demand of energy requirement as well as exhaustion of traditional fuels, although the application of polymers’ capacitor is quite different from batteries, ferroelectric polymers in energy storage capacitor application show renewed interest to meet the demand . In linear approximation, the energy storage density of a dielectric material is proportional to the product of dielectric constant and the square of the applied electric field .…”

Colloidal Energetic Systems

“…The capability of developing functional inks providing electrochemical properties, eventually based on a suspension of functional NPs dispersed in a solvent carrier, also exists (ii) In situ sensing capability : The sensing of environmental scalar or vector fields, such as a magnetic field B , temperature T , hydrostatic pressure p , or gravity, through a liquid system, could be done using a variety of choices exploiting relevant effects and, in particular, using FFs . For example, focusing on magnetic field measurements, Hall effect (HE)/magnetoresistance/magnetoimpedance/optical magnetoresistance are all examples of mutual effects that can be sensed …”

“…(iv) Data processing : It is possible to perform data processing functions, as demonstrated in experimental prototypes of computing devices using excitation wave fronts in active nonlinear media (Belousov–Zhabotinsky reaction), crystallization fronts in “hot ice,” propagating lamellipodia in slime mould Physarum polycephalum , electrical properties of organic conductive polymers, and spiking‐based logic in TiO 2 sol–gel memristors (v) Mobility : The CAS macroscopic motion could be controlled externally through electromagnetic fields, thermal gradients, pressure gradients, and modulated light, leading to actively controlled propulsion or passive taxis (vi) Communication : Retaining the advantage of the liquid form, we may think of localized colloidal microantennas (LoCµAs), based on plasmonic resonance and localized on the external surface of the main portion of the fluid …”

“…Finally, the variability of technology needs across the expanse of prospective surface missions is immense, yet technology development funding is extremely limited. Colloid‐based robotic systems have been shown to represent an extremely attractive alternative to conventional robotic systems, and their development has still to come . A liquid autonomous robot is an adaptive platform capable of exploring unpredictable terrains, to navigate through small holes, with potential applications in the fields of harsh environments such as planetary gas giants, comets and asteroids, ocean and lake depths, rough terrains, post‐earthquake areas, and so on.…”