Experimental Brain Research

The use of wearable equipment and sensing devices to monitor physical activities, whether for well-being, sports monitoring, or medical rehabilitation, has expanded rapidly due to the evolution of sensing techniques, cheaper integrated circuits, and the development of connectivity technologies. In this scenario, this paper presents a state-of-the-art review of sensors and systems for rehabilitation and health monitoring. Although we know the increasing importance of data processing techniques, our focus was on analyzing the implementation of sensors and biomedical applications. Although many themes overlap, we organized this review based on three groups: Sensors in Healthcare, Home Medical Assistance, and Continuous Health Monitoring; Systems and Sensors in Physical Rehabilitation; and Assistive Systems.

https://www.mdpi.com/1424-8220/20/15/4063/pdf

Sensors and Systems for Physical Rehabilitation and Health Monitoring-A Review.

New technologies and Amyotrophic Lateral Sclerosis - Which step forward rushed by the COVID-19 pandemic?

Wearable technologies are emerging as a useful tool with many different applications. While these devices are worn on the human body and can capture numerous data types, this literature review focuses specifically on wearable use for performance enhancement and risk assessment in industrial- and sports-related biomechanical applications. Wearable devices such as exoskeletons, inertial measurement units (IMUs), force sensors, and surface electromyography (EMG) were identified as key technologies that can be used to aid health and safety professionals, ergonomists, and human factors practitioners improve user performance and monitor risk. IMU-based solutions were the most used wearable types in both sectors. Industry largely used biomechanical wearables to assess tasks and risks wholistically, which sports often considered the individual components of movement and performance. Availability, cost, and adoption remain common limitation issues across both sports and industrial applications.

/pdf/wearables-for-biomechanical-performance-optimization-and-kl7o5ffl.pdf

Wearables for Biomechanical Performance Optimization and Risk Assessment in Industrial and Sports Applications

Passive wearable exoskeletons are desirable as they can provide assistance during user movements while still maintaining a simple and low-profile design. These can be useful in industrial tasks where an ergonomic device could aid in load lifting without inconveniencing them and reducing fatigue and stress in the lower limbs. The SpringExo is a coil-spring design that aids in knee extension. In this paper, we describe the muscle activation of the knee flexors and extensors from seven healthy participants during repeated squats. The outcome measures are the timings of the key events during squat, flexion angle, muscle activation of rectus femoris and bicep femoris, and foot pressure characteristics of the participants. These outcome measures assess the possible effects of the device during lifting operations where reduced effort in the muscles is desired during ascent phase of the squat, without changing the knee and foot kinematics. The results show that the SpringExo significantly decreased rectus femoris activation during ascent (−2%) without significantly affecting either the bicep femoris or rectus femoris muscle activations in descent. This implies that the user could perform a descent without added effort and ascent with reduced effort. The exoskeleton showed other effects on the biomechanics of the user, increasing average squat time (+0.02 s) and maximum squat time (+0.1 s), and decreasing average knee flexion angle (−4°). The exoskeleton has no effect on foot loading or placement, that is, the user did not have to revise their stance while using the device.

Passive knee exoskeletons in functional tasks: Biomechanical effects of a SpringExo coil-spring on squats

Biomechanical differences during ascent on regular stairs and on a stairmill.

Objective This paper presents the first study where a dynamic neck brace was used to characterize the head motion of ALS patients while concurrently recording the surface electromyography (EMG) of the neck muscles. Methods Eleven ALS patients and 10 age-matched healthy controls consented and participated in an experiment. Each participant was asked to perform three single-plane motions of the head-neck that included flexion-extension in the sagittal plane, lateral bending in the coronal plane, and axial rotation in the transverse plane. Each motion was performed in a cycle and was repeated five times at self-selected speeds. Results During single-plane flexion-extension under gravity, compared to healthy peers, ALS patients showed a shorter duration to reach the maximum flexion and an earlier EMG onset in the neck extensors starting from the neutral. The brace measures in activation of the neck muscles in ALS patients were well correlated with clinically measured scores, such as the ALSFRS-r and the FVC. The activation duration of sternocleidomastoid, used to rotate the head, correlated well with the ALSFRS-r and FVC in ALS patients during axial rotation. Interpretation The ability to synchronously activate a pair of muscles to execute single-plane motions in ALS patients seems to have been compromised due to the disease and potentially results in head drop. The neck brace measures can be adapted in the clinic to complement self-reporting in ALS patients and used to assess the head drop and progress of the disease.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/acn3.50864

A robotic neck brace to characterize head-neck motion and muscle electromyography in subjects with amyotrophic lateral sclerosis

Coordinated head–neck movement is a challenge for patients with neurological disorders, such as cerebral palsy and amyotrophic lateral sclerosis. Neck collars are commonly used to stabilize the head–neck in these patients. These collars are mostly rigid and uncomfortable to wear for extended periods of time. We have developed a robotic neck brace to assist head–neck motion. In this letter, we focus on using the robotic neck brace for training of the head-neck motion using forces applied on the head. A force controller is implemented to deliver a moment to correct the head motion in an ‘assist-as-needed’ fashion. A human study was designed to assess the performance of the robotic neck brace with the force controller. Ten young healthy adults participated in the experiment. They were asked to perform a lateral bending motion in the coronal plane of the head-neck with and without the assistance of the brace. The motions were conducted under two conditions: i) with visual feedback, ii) with visual and force feedback. We found that the rotational movement errors were significantly reduced ( $p ) during training with the force field when compared to visual feedback alone. As expected, this change was not retained during post-training. We conclude that the force controller is able to provide the desirable force assistance to help coordinate the head motion.

Using a Robotic Neck Brace for Movement Training of the Head–Neck

Head-neck interfaces have the potential to command and control orientation tasks when the hand-wrist is not available for use as a joystick. We pose the question in this paper–How well can the head-neck be used to perform orientation tasks when compared to the hand-wrist? Anatomically, the motion of the head-neck is similar to that of the hand-wrist. We hypothesize that the head-neck motion can be as effective as the motion of the hand-wrist to control orientation tasks. A study was designed to characterize the ability of head-neck to command and control general orientation tasks. Fourteen healthy participants were asked to control the head orientation of an avatar on a computer screen using the motion of their head-neck and hand-wrist, measured by a robotic neck brace and a conventional joystick, respectively. Visual feedback was given to the participants with the display of the target and the actual head orientations of the avatar. The outcomes were defined for comparison between the head-neck and hand-wrist motions as follows: 1) mean absolute error; 2) time delay in tracking continuous orientation trajectories; and 3) settling time to reach target orientations. The results showed that the performance outcomes were significantly better with the hand-wrist than that of the head-neck when used as a joystick. However, all participants successfully completed the tasks with the head-neck. This demonstrates that the head-neck can be used as a joystick for controlling three dimensional object orientations, even though it may not be as dexterous as the hand-wrist. These results have fundamental implications in the design of devices and interfaces with the human head-neck.

Biing-Chwen Chang

Papers

Biomechanical differences during ascent on regular stairs and on a stairmill.

A robotic neck brace to characterize head-neck motion and muscle electromyography in subjects with amyotrophic lateral sclerosis

Using a Robotic Neck Brace for Movement Training of the Head–Neck

Using the Motion of the Head-Neck as a Joystick for Orientation Control

Passive knee exoskeletons in functional tasks: Biomechanical effects of a SpringExo coil-spring on squats