3D-Printed Soft Pneumatic Robotic Digit Based on Parametric Kinematic Model for Finger Action Mimicking.

A robotic digit with shape modulation, allowing personalized and adaptable finger motions, can be used to restore finger functions after finger trauma or neurological impairment. A soft pneumatic robotic digit consisting of pneumatic bellows actuators as biomimetic artificial joints is proposed in this study to achieve specific finger motions. A parametric kinematic model is employed to describe the tip motion trajectory of the soft pneumatic robotic digit and guide the actuator parameter design (i.e., the pressure supply, actuator material properties, and structure requirements of the adopted pneumatic bellows actuators). The direct 3D printing technique is adopted in the fabrication process of the soft pneumatic robotic digit using the smart material of thermoplastic polyurethane. Each digit joint achieves different ranges of motion (ROM; bending angles of distal, proximal, and metacarpal joint are 107°, 101°, and 97°, respectively) under a low pressure of 30 kPa, which are consistent with the functional ROM of a human finger for performing daily activities. Theoretical model analysis and experiment tests are performed to validate the effectiveness of the digit parametric kinematic model, thereby providing evidence-based technical parameters for the precise control of dynamic pressure dosages to achieve the required motions.

Biomimetic Artificial Joints Based on Multi-Material Pneumatic Actuators Developed for Soft Robotic Finger Application.

To precisely achieve a series of daily finger bending motions, a soft robotic finger corresponding to the anatomical range of each joint was designed in this study with multi-material pneumatic actuators. The actuator as a biomimetic artificial joint was developed on the basis of two composite materials of different shear modules, and the pneumatic bellows as expansion parts was restricted by frame that made from polydimethylsiloxane (PDMS). A simplified mathematical model was used for the bending mechanism description and provides guidance for the multi-material pneumatic actuator fabrication (e.g., stiffness and thickness) and structural design (e.g., cross length and chamber radius), as well as the control parameter optimization (e.g., the air pressure supply). An actuation pressure of over 70 kPa is required by the developed soft robotic finger to provide a full motion range (MCP = 36°, PIP = 114°, and DIP = 75°) for finger action mimicking. In conclusion, a multi-material pneumatic actuator was designed and developed for soft robotic finger application and theoretically and experimentally demonstrated its feasibility in finger action mimicking. This study explored the mechanical properties of the actuator and could provide evidence-based technical parameters for pneumatic robotic finger design and precise control of its dynamic air pressure dosages in mimicking actions. Thereby, the conclusion was supported by the results theoretically and experimentally, which also aligns with our aim to design and develop a multi-material pneumatic actuator as a biomimetic artificial joint for soft robotic finger application.

Wearable Physiological Monitoring System Based on Electrocardiography and Electromyography for Upper Limb Rehabilitation Training.

Secondary injuries are common during upper limb rehabilitation training because of uncontrollable physical force and overexciting activities, and long-time training may cause fatigue and reduce the training effect. This study proposes a wearable monitoring device for upper limb rehabilitation by integrating electrocardiogram and electromyogram (ECG/EMG) sensors and using data acquisition boards to obtain accurate signals during robotic glove assisting training. The collected ECG/EMG signals were filtered, amplified, digitized, and then transmitted to a remote receiver (smart phone or laptop) via a low-energy Bluetooth module. A software platform was developed for data analysis to visualize ECG/EMG information, and integrated into the robotic glove control module. In the training progress, various hand activities (i.e., hand closing, forearm pronation, finger flexion, and wrist extension) were monitored by the EMG sensor, and the changes in the physiological status of people (from excited to fatigue) were monitored by the ECG sensor. The functionality and feasibility of the developed physiological monitoring system was demonstrated by the assisting robotic glove with an adaptive strategy for upper limb rehabilitation training improvement. The feasible results provided a novel technique to monitor individual ECG and EMG information holistically and practically, and a technical reference to improve upper limb rehabilitation according to specific treatment conditions and the users' demands. On the basis of this wearable monitoring system prototype for upper limb rehabilitation, many ECG-/EMG-based mobile healthcare applications could be built avoiding some complicated implementation issues such as sensors management and feature extraction.

Flexible sensor matrix film-based wearable plantar pressure force measurement and analysis system.

Plantar pressure force data derived from gait and posture are commonly used as health indicators for foot diagnosis, injury prevention, and rehabilitation. This study developed a wearable plantar pressure force measurement and analysis (WPPFMA) system based on a flexible sensor matrix film to monitor plantar pressure force in real time. The developed system comprised a flexible sensor matrix film embedded in the insole of the shoe, a wearable data acquisition (DAQ) device with a Bluetooth module, and dedicated software with an intuitive graphical user interface for displaying the plantar pressure force data from receivers by using a terminal unit (laptop or smart-phone). The flexible sensor matrix film integrated 16 piezoresistive cell sensors to detect pressure force at different anatomical zones of the plantar and under different body positions. The signals from the flexible sensor matrix film were collected using the DAQ module embedded in the shoe and transmitted to the receivers through Bluetooth. The real-time display and analysis software can monitor, visualize, and record the detailed plantar pressure force data, such as average pressure force, maximum pressure force, and pressure force distributions and variations over time. The outcomes of the trials in which the system was worn revealed the applicability of the developed WPPFMA system for monitoring plantar pressure force under static and dynamic wearing conditions. The plantar pressure force data derived from this system provide valuable insights for personal foot care, gait analysis, and clinical diagnosis.

Fluid-Structure Coupling Model and Experimental Validation of Interaction Between Pneumatic Soft Actuator and Lower Limb.

Pneumatic soft actuators (PSAs) are components that produce predesigned motion or force in different end-use devices. PSAs are lightweight, flexible, and compatible in human-machine interaction. The use of PSAs in compression therapy has proven promising in proactive pressure delivery with a wide range of dosages for treatment of chronic venous insufficiency and lymphedema. However, effective design and control of PSAs for dynamic pressure delivery have not been fully elaborated. The purpose of this study is to explore interactive working mechanisms between a PSA and lower limbs through establishing fluid-structure coupling models, an intermittent pneumatic compression (IPC) testing system, and conducting experimental validation. The developed IPC testing system consisted of a PSA unit (multichambered bladders laminated with an external textile shell), a pneumatic controller, and various real-time pressure monitoring sensors and accessory elements. The established coupling model characterized the dynamic response process with varying design parameters of the PSA unit, and demonstrated that the design of initial thickness, stiffness, and air mass flow of the PSA, as well as stiffness of limb tissues of the users, influenced PSA-lower limb interactions and resultant pressure dosages. The simulated results presented a favorable agreement with the experimental data collected by the IPC testing system. This study enhanced understanding of PSA-lower limb interactive working mechanisms and provided an evidence-based technical guidance for functional design of PSA. These results contribute to improving the efficacy of dynamic compression therapy for promotion of venous hemodynamics and user compliance in practice.

Dynamic Interface Pressure Monitoring System for the Morphological Pressure Mapping of Intermittent Pneumatic Compression Therapy.

Intermittent pneumatic compression (IPC) is a proactive compression therapeutic technique in the prophylaxis of deep vein thrombosis, reduction of limb edema, and treatment of chronic venous ulcers. To appropriately detect and analyze biomechanical pressure profiles delivered by IPC in treatment, a dynamic interface pressure monitoring system was developed to visualize and quantify morphological pressure mapping in the spatial and temporal domains in real time. The system comprises matrix soft sensors, a smart IPC device, a monitoring and analysis software, and a display unit. The developed soft sensor fabricated by an advanced screen printing technology was used to detect intermitted pressure by an IPC device. The pneumatic pressure signals inside the bladders of the IPC were also transiently collected by a data acquisition system and then transmitted to the computer through Bluetooth. The experimental results reveal that the developed pressure monitoring system can perform the real-time detection of dynamic pressures by IPC and display the morphological pressure mapping multi-dimensionally. This new system provides a novel modality to assist in the effective evaluation of proactive compression therapy in practice. The study results contribute to understanding the working mechanisms of IPC and improving its functional design based on intuitive biomechanical characteristics of compression delivery profiles.