Liquid marbles (LMs) have recently attracted interest for use as cargo carriers in digital microfluidics and have successfully been implemented as signal carriers in collisionbased unconventional computing circuits. Both application domains require LMs to roll over substantial distances and to survive a certain number of collisions without degrading. To evaluate the lifetime of LMs being subjected to movement and impact stresses, we have selected four types of coating to investigate: polytetrafluoroethylene (PTFE), ultra-high density polyethylene (PE), Ni, and a mixture of Ni with PE (Ni-PE). Hierarchies of robustness have been constructed which showed that pure PE LMs survived the longest when stationary and in motion. Pure PTFE LMs were shown to be the least resilient to multiple impacts and provided minimal protection against evaporative losses at small volumes (2 μl and 5 μl), but showed a good evaporative stability when stationary for larger LMs (10 μl). Conversely, PE LMs showed a remarkable ability to withstand multiple impacts and were also stable when considering just passive evaporation. Hybrid Ni-PE LMs exhibited more resilience to multiple impacts compared to Ni LMs. Thus, when designing liquid marble devices it is paramount to determine impact pathways and select appropriate coating materials.

Liquid marbles are microliter droplets of liquid, encapsulated by self-organized hydrophobic particles at the liquid/air interface. They offer an efficient approach for manipulating liquid droplets and compartmentalizing reactions in droplets. Digital fluidic devices employing liquid marbles might benefit from having embedded computing circuits without electronics and moving mechanical parts (apart from the marbles). We present an experimental implementation of a collision gate with liquid marbles. Mechanics of the gate follows principles of Margolus’ soft-sphere collision gate. Boolean values of the inputs are given by the absence (FALSE) or presence (TRUE) of a liquid marble. There are three outputs: two outputs are trajectories of undisturbed marbles (they only report TRUE when just one marble is present at one of the inputs), one output is represented by trajectories of colliding marbles (when two marbles collide they lose their horizontal momentum and fall), this output reports TRUE only when two marbles are present at inputs. Thus the gate implements AND and AND-NOT logical functions. We speculate that by merging trajectories representing AND-NOT output into a single channel one can produce a one-bit half-adder. Potential design of a one-bit full-adder is discussed, and the synthesis of both a pure nickel metal and a hybrid nickel/polymer liquid marble is reported.

In Belousov–Zhabotinsky (BZ) type reactions, chemical oxidation waves can be exploited to produce reaction-diffusion processors. This paper reports on a new method of encapsulating BZ solution in a powder coating of either polyethylene (PE) or polytetrafluoroethylene (PTFE), to produce BZ liquid marbles (LMs). BZ LMs have solid–liquid interfaces compared to previously reported encapsulation systems, BZ emulsions and BZ vesicles. Oscillation studies on individual LMs established PE-coated LMs were easier to prepare and more robust than PTFE-coated LMs. Therefore, this coating was used to study BZ LMs positioned in ordered and disordered arrays. Sporadic transfer of excitation waves was observed between LMs in close proximity to each other. These results lay the foundations for future studies on information transmission and processing arrays of BZ LMs. Future work aims to elucidate the effect of other physical stimuli on the dynamics of chemical excitation waves within these systems.

Mycelium-bound composites are potential alternatives to conventional materials for a variety of applications, including thermal and acoustic building panels and product packaging. If the reactions of live mycelium to environmental conditions and stimuli are taken into account, it is possible to create functioning fungal materials. Thus, active building components, sensory wearables, etc. might be created. This research describes the electrical sensitivity of fungus to changes in the moisture content of a mycelium-bound composite. Trains of electrical spikes initiate spontaneously in fresh mycelium-bound composites with a moisture content between $$\sim$$∼ 95% and $$\sim$$∼ 65%, and between $$\sim$$∼ 15% and $$\sim$$∼ 5% when partially dried. When the surfaces of mycelium-bound composites were partially or totally encased with an impermeable layer, increased electrical activity was observed. In fresh mycelium-bound composites, electrical spikes were seen both spontaneously and when induced by water droplets on the surface. Also explored is the link between electrical activity and electrode depth. Future designs of smart buildings, wearables, fungi-based sensors, and unconventional computer systems may benefit from fungi configurations and biofabrication flexibility.

A mechanical flip-flop actuator has been developed that allows for the facile re-routing and distribution of liquid marbles (LMs) in digital microfluidic devices. Shaped loosely like a triangle, the actuating switch pivots from one bistable position to another, being actuated by the very low mass and momentum of a LM rolling under gravity (~4 × 10⁻⁶ kg ms⁻¹). The actuator was laser-cut from cast acrylic, held on a PTFE coated pivot, and used a PTFE washer. Due to the rocking motion of the switch, sequential LMs are distributed along different channels, allowing for sequential LMs to traverse parallel paths. This distributing effect can be easily cascaded, for example to evenly divide sequential LMs down four different paths. This lightweight, cheap and versatile actuator has been demonstrated in the design and construction of a LM-operated mechanical multiplication device — establishing its effectiveness. The actuator can be operated solely by gravity, giving it potential use in point-of-care devices in low resource areas.