This work explores the sensing potential of mycelium with the intention of incorporating this as an intrinsic sensing mechanism within structural materials. Infrastructure plays a critical role in modern societies with regard to economic productivity, social cohesion, and community well-being. By merging materials that are used for construction, such as concrete with living components, we aim to add intrinsic monitoring mechanisms that could usher in a new era of structural monitoring solutions. Mycelium, the vegetative part of the fungi, has been shown to have an extracellular electrical potential that changes when exposed to various physical and chemical stimuli, making it an ideal candidate for this purpose. In this preliminary investigation, we analyse the electrical behaviour of mycelium exploring its potential use as a sensing material within infrastructure components.
Piezoelectric transducers can convert the mechanical energy into electrical one with their direct piezoelectric effect, or reciprocally convert the electrical energy into mechanical one with their inverse piezoelectric effect. Various applications were developed based on either of these two effects, for example, sensors and energy harvesters using the direct piezoelectric effect and actuators using the inverse piezoelectric effect. Yet, few of them have fulfilled the multi-functional purposes, which are useful in some application scenarios. This paper proposes a bidirectional energy conversion circuit (BECC) solution for the time-division energy harvesting and actuating purposes. The circuit topology is derived from the synchronized triple bias-flip circuit, which was formerly used for energy harvesting enhancement. The circuit topology and control logic for energy harvesting and actuating modes are discussed in details. Two designs are studied for investigating the potential applications of the BECC. In the linear piezoelectric structure, the BECC can be used to provide vibration excitation and then reclaim the vibration energy. Such time-division energy injection and reclamation can be used in some non-destructive structural health evaluations. The proposed BECC can be also used to realize the controllable orbit exciter in nonlinear piezoelectric energy harvesting systems. It is the first time to realize a compact and integrated orbit exciter and energy harvester by using a single interface circuit. Simulations and experiments are carried out for validating the performance of the BECC towards versatile engineering designs.
In the studies of piezoelectric energy harvesting (PEH) systems, literature has shown that the circuit solution has a significant effect towards the enhancement of energy harvesting capability under resonance. Some studies started to investigate its bandwidth-broadening effect recently. This paper provides a comprehensive comparison on the impact of circuit solutions towards the broadband and high-capability energy harvesting. The comparison is intuitively presented based on the equivalent impedance model. The joint dynamics and harvested power of the PEH systems using different interface circuits are thoroughly discussed. Simulation and experiments show good agreement with the analysis. It is shown that, within the existing circuit solutions, the currently proposed phase-variable synchronized parallel triple bias-flip (PV-P-S3BF) circuit provides the most extensive span of electrically induced damping and electrically induced stiffness/mass. By tuning the values of the two equivalent components in operation, the tasks of harvesting capability enhancement and bandwidth broadening can be simultaneously made by using PV-P-S3BF.
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