The composition of fine-ground lead zirconate-titanate powder Pb(Zr_0.52Ti_0.48)O₃, suspended in PZT and bismuth titanate (BiT) solutions, is deposited on the curved surface of IN718 and IN738 nickel-based supper alloy substrates up to 100 µm thickness. Photochemical metal organic and infiltration techniques are implemented to produce smooth, semi-dense, and crack-free random orientated thick piezoelectric films as piezo-sensors, free of any dopants or thickening polymers. Every single layer of the deposited films is heated at 200 °C with 10 wt.% excess PbO, irradiated by ultraviolet lamp (365 nm, 6 watt) for 10 min, pyrolyzed at 400 °C, and subsequently annealed at 700 °C for one hour. This process is repeated successively until reaching the desired thickness. Au and Pt thin films are deposited as the bottom and top electrodes using evaporation and sputtering methods, respectively. PZT/PZT and PZT/BiT composite films are then characterized and compared to similar PZT and BiT thick films deposited on the similar substrates. The effect of the composition and deposition process is also investigated on the crystalline phase development and microstructure morphology as well as the dielectric, ferroelectric, and piezoelectric properties of piezo-films. The maximum remnant polarization of P_r = 22.37 ± 0.01, 30.01 ± 0.01 µC/cm², the permittivity of ε_r = 298 ± 3, 566 ± 5, and piezoelectric charge coefficient of d₃₃ = 126, 148 m/V were measured versus the minimum coercive field of E_c = 50, 20 kV/cm for the PZT/PZT and PZT/BiT thick films, respectively. The thick film piezo-sensors are developed to be potentially used at frequency bandwidth of 1–5 MHz for rotary structural health monitoring and also in other industrial or medical applications as a transceiver.

This journal review article focuses on the use of assistive and rehabilitative exoskeletons as a new opportunity for individuals with diminished mobility. The article aims to identify gaps and inconsistencies in state-of-the-art assistive and rehabilitative devices, with the overall goal of promoting innovation and improvement in this field. The literature review explores the mechanisms, actuators, and sensing procedures employed in each application, specifically focusing on passive shoulder supports and active soft robotic actuator gloves. Passive shoulder supports are an excellent option for bearing heavy loads, as they enable the load to be evenly distributed across the shoulder joint. This, in turn, reduces stress and strain around the surrounding muscles. On the other hand, the active soft robotic actuator glove is well suited for providing support and assistance by mimicking the characteristics of human muscle. This review reveals that these devices improve the overall standard of living for those who experience various impairments but also encounter limitations requiring redress. Overall, this article serves as a valuable resource for individuals working in the field of assistive and rehabilitative exoskeletons, providing insight into the state of the art and potential areas for improvement.

Surface stiffness plays an important role in human locomotion mechanics and can affect both the energy expenditure and the gait of human. In order to be able to systematically analyze these effects, this paper presents the design and development of a novel treadmill with the ability to regulate stiffness of the surface. The novelty of the system is on its stiffness adjustment mechanism that can achieve: First, purely vertical displacement of the surface, second, wide range of stiffness regulation, third, bilateral stiffness regulation for the left and the right legs, independently, and fourth, consistent stiffness of the surface, independent of the location of the person on the treadmill. The presented system is a unique tool to systematically study the effect of surface compliance on the metabolic cost and the dynamics of human walking. This can also introduce new rehabilitation strategies for mobility impaired patients. In order to show the proof of concept, we also present preliminary experiments to show the effect of surface stiffness regulation on the metabolic cost and gait of a healthy subject.

Variable stiffness mechanisms are able to mechanically reconfigure themselves in order to adjust their system stiffness. It is generally accepted that only antagonistic designs, featuring quadratic springs, can produce linear spring-like behaviour (i.e., a linear relationship between the displacement and its resultant force). However, these antagonistic designs typically are not as energy efficient as series-based designs. In this work, we propose a novel variable stiffness mechanism that can achieve both linear-spring behaviour whilst maintaining an energy efficient characteristic. This paper will present the working principle, mechanical design and characterization of the joints stiffness properties (verified via experimental procedure). The pros and cons of this novel design with reference to the other Variable Stiffness Actuator (VSA) designs will be discussed based on experimental results and in the context of general machining tasks.