Background Soft, wearable, powered exoskeletons are novel devices that may assist rehabilitation, allowing users to walk further or carry out activities of daily living. However, soft robotic exoskeletons, and the more commonly used rigid exoskeletons, are not widely adopted clinically. The available evidence highlights a disconnect between the needs of exoskeleton users and the engineers designing devices. This review aimed to explore the literature on physiotherapist and patient perspectives of the longer-standing, and therefore greater evidenced, rigid exoskeleton limitations. It then offered potential solutions to these limitations, including soft robotics, from an engineering standpoint. Methods A state-of-the-art review was carried out which included both qualitative and quantitative research papers regarding patient and/or physiotherapist perspectives of rigid exoskeletons. Papers were themed and themes formed the review’s framework. Results Six main themes regarding the limitations of soft exoskeletons were important to physiotherapists and patients: safety; a one-size-fits approach; ease of device use; weight and placement of device; cost of device; and, specific to patients only, appearance of the device. Potential soft-robotics solutions to address these limitations were offered, including compliant actuators, sensors, suit attachments fitting to user’s body, and the use of control algorithms. Conclusions It is evident that current exoskeletons are not meeting the needs of their users. Solutions to the limitations offered may inform device development. However, the solutions are not infallible and thus further research and development is required.

Upper limb impairments and weakness are common post-stroke and with advanced aging. Rigid exoskeletons have been developed as a potential solution, but have had limited impact. In addition to user concerns about safety, their weight and appearance, the rigid attachment and typical anchoring methods can result in skin damage. In this paper, we present a soft, fabric-based pneumatic sleeve, which can shrink from a loose fit to a tight fit in order to anchor to the limbs temporarily, thereby enabling the application of mechanical assistance only when needed. The sleeve is comfortable, ergonomic and can be embedded unobtrusively with clothing. A mathematical model is built to simulate and design sleeves with different geometric parameters. The best sleeve was capable of generating a friction force of 98 N on the limb when inflated to 25 kPa. This sleeve was used to create a wearable assistive device, integrated with a cable-driven actuator. This device was able to lift a 1.44 kg forearm rig up to 95 degree at low pressure of 20 kPa. The device was tested with six healthy participants, in terms of fit, comfort and assistive functionality. The average acceptable sleeve pressure was found to be 33±4.7 kPa. All participants liked the appearance of the sleeve, with a high average perceived assistance score of 7.33±1.6 (out of 10). The shrink-to-fit sleeve is expected to significantly increase the development and adoption of soft robotic assistive devices and emerging powered clothing.

The Electro-pneumatic Pump (EPP) is a lightweight, flexible electrostatic pump that uses a dielectric-liquidamplified zipping mechanism to control air volume and pressure and generate high air flow rate. In previous studies, the EPP, made of rectangular insulated electrodes, was capable of inflating/deflating pneumatic actuators and operating as a low power soft pump. This article explores a range of designs for the EPP electrodes to increase pressure generation, air transference and flow rate. As a result, the new EPP was able to generate a maximum pressure of 12.24 kPa, or a pressure difference of 11.25 kPa, corresponding to 481% improvement from the previous study. Additional liquid dielectric at 18% of the maximum available volume enabled the EPP to attain maximum EPP performance. The new design of the EPP was developed by combining two identical zipping regions and minimising the inactive region. Different actuator dimensions and actuation frequencies were investigated. The pump was capable of delivering a maximum flow rate of 238 ml/min at atmospheric pressure (48% improvement) at low power consumption of 0.4 Watt, and it could operate up to 4.47 kPa. It was found that the shape of the zipping region and the behaviour of the integrated compliant spring significantly influences the performance of the device. Lastly, approaches to further improve the EPP pump are discussed.