Publications by Type: Journal Article

J. Kang, K. Ghonasgi, C. Walsh, and S. Agrawal, “Simulating Hemiparetic Gait in Healthy Subjects using TPAD with a Closed-loop Controller,” IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol. 27, no. 5, pp. 974-983, 2019. PDF
F. Connolly, D. A. Wagner, C. J. Walsh, and K. Bertoldi, “Sew-free anisotropic textile composites for rapid design and manufacturing of soft wearable robots,” Extreme Mechanics Letters, vol. 27, pp. 52-58, 2019. Publisher's Version PDF
M. Grimmer, et al., “Comparison of the human-exosuit interaction using ankle moment and ankle positive power inspired walking assistance,” Journal of Biomechanics, vol. 83, no. 23, pp. 76-84, 2019. PDF
M. Grimmer, R. Riener, C. J. Walsh, and A. Seyfarth, “Mobility related physical and functional losses due to aging and disease - a motivation for lower limb exoskeletons,” Journal of NeuroEngineering and Rehabilitation, vol. 16, no. 1, 2019. PDF
S. Lee, et al., “Autonomous multi-joint soft exosuit with augmentation-power-based control parameter tuning reduces energy cost of loaded walking,” Journal of NeuroEngineering and Rehabilitation, vol. 15, no. 1, pp. 66, 2018. PDF
M. Moyne, M. Herman, K. Z. Gajos, C. Walsh, and D. P. Holland, “The Development and Evaluation of DEFT, a Web-Based Tool for Engineering Design Education,” IEEE Transaction on Learning Technologies, vol. 11, no. 4, 2018. PDF
F. Porciuncula, et al., “Wearable movement sensors for rehabilitation: A focused review of technological and clinical advances,” PM&R, vol. 10, no. 9, pp. S220-232, 2018. PDF
L. Cappello, et al., “Exploiting Textile Mechanical Anisotropy for Fabric-Based Pneumatic Actuators,” Soft Robotics, 2018. PDF Supplementary PDF Video
L. Cappello, et al., “Assisting hand function after spinal cord injury with a fabric-based soft robotic glove,” Journal of NeuroEngineering and Rehabilitation, vol. 15, no. 1, pp. 59, 2018. Publisher's VersionAbstract
Spinal cord injury is a devastating condition that can dramatically impact hand motor function. Passive and active assistive devices are becoming more commonly used to enhance lost hand strength and dexterity. Soft robotics is an emerging discipline that combines the classical principles of robotics with soft materials and could provide a new class of active assistive devices. Soft robotic assistive devices enable a human-robot interaction facilitated by compliant and light-weight structures. The scope of this work was to demonstrate that a fabric-based soft robotic glove can effectively assist participants affected by spinal cord injury in manipulating objects encountered in daily living.
W. Whyte, et al., “Sustained release of targeted cardiac therapy with a replenishable implantable epicardial reservoir,” Nature Biomedical Engineering, vol. 2, pp. 416-428, 2018. PDF Supplementary PDF
M. A. Horvath, et al., “Towards Alternative Approaches for Coupling of a Soft Robotic Sleeve to the Heart,” Annals of Biomedical Engineering, 2018. Publisher's VersionAbstract
Efficient coupling of soft robotic cardiac assist devices to the external surface of the heart is crucial to augment cardiac function and represents a hurdle to translation of this technology. In this work, we compare various fixation strategies for local and global coupling of a direct cardiac compression sleeve to the heart. For basal fixation, we find that a sutured Velcro band adheres the strongest to the epicardium. Next, we demonstrate that a mesh-based sleeve coupled to the myocardium improves function in an acute porcine heart failure model. Then, we analyze the biological integration of global interface material candidates (medical mesh and silicone) in a healthy and infarcted murine model and show that a mesh interface yields superior mechanical coupling via pull-off force, histology, and microcomputed tomography. These results can inform the design of a therapeutic approach where a mesh-based soft robotic DCC is implanted, allowed to biologically integrate with the epicardium, and actuated for active assistance at a later timepoint. This strategy may result in more efficient coupling of extracardiac sleeves to heart tissue, and lead to increased augmentation of heart function in end-stage heart failure patients.
C. J. Walsh, “Human-in-the-loop development of soft wearable robots,” Nature Review Materials, vol. 3, pp. 78-80, 2018. Publisher's VersionAbstract

The field of soft wearable robotics offers the opportunity to wear robots like clothes to assist the movement of specific body parts or to endow the body with functionalities. Collaborative efforts of materials, apparel and robotics science have already led to the development of wearable technologies for physical therapy. Optimizing the human–robot system by human-in-the-loop approaches will pave the way for personalized soft wearable robots for a variety of applications.

D. P. Holland, C. J. Walsh, and G. J. Bennett, “A qualitative investigation of design knowledge reuse in project-based mechanical design courses,” European Journal of Engineering Education, pp. 1-16, 2018. Publisher's Version PDF
D. Holland, S. Berndt, M. Herman, and C. Walsh, “Growing the Soft Robotics Community Through Knowledge-Sharing Initiatives,” Soft Robotics, vol. 5, no. 2, pp. 119-121, 2018. Publisher's Version PDF
S. Mohammed, et al., “Wearable Robotics for Motion Assistance and Rehabilitation [TC Spotlight],” IEEE Robotics Automation Magazine, vol. 25, no. 1, pp. 19-28, 2018. PDF
J. Gafford, H. Aihara, C. Thompson, R. Wood, and C. Walsh, “Distal Proprioceptive Sensor for Motion Feedback in Endoscope-Based Modular Robotic Systems,” IEEE Robotics and Automation Letters, vol. 3, no. 1, pp. 171-178, 2018. PDF
J. Bae, et al., “Biomechanical mechanisms underlying exosuit-induced improvements in walking economy after stroke,” Journal of Experimental Biology, 2018. Publisher's VersionAbstract
{Stroke-induced hemiparetic gait is characteristically asymmetric and metabolically expensive. Weakness and impaired control of the paretic ankle contribute to reduced forward propulsion and ground clearance—walking subtasks critical for safe and efficient locomotion. Targeted gait interventions that improve paretic ankle function after stroke are therefore warranted. We have developed textile-based, soft wearable robots that transmit mechanical power generated by off-board or body-worn actuators to the paretic ankle using Bowden cables (soft exosuits) and have demonstrated the exosuits can overcome deficits in paretic limb forward propulsion and ground clearance, ultimately reducing the metabolic cost of hemiparetic walking. This study elucidates the biomechanical mechanisms underlying exosuit-induced reductions in metabolic power. We evaluated the relationships between exosuit-induced changes in the body center of mass (COM) power generated by each limb, individual joint powers, and metabolic power. Compared to walking with an exosuit unpowered, exosuit assistance produced more symmetrical COM power generation during the critical period of the step-to-step transition (22.4±6.4% more symmetric). Changes in individual limb COM power were related to changes in paretic (R2= 0.83
Y. Ding, M. Kim, S. Kuindersma, and C. J. Walsh, “Human-in-the-loop optimization of hip assistance with a soft exosuit during walking,” Science Robotics, vol. 3, no. 15, pp. eaar5438, 2018. Publisher's VersionAbstract
Wearable robotic devices have been shown to substantially reduce the energy expenditure of human walking. However, response variance between participants for fixed control strategies can be high, leading to the hypothesis that individualized controllers could further improve walking economy. Recent studies on human-in-the-loop (HIL) control optimization have elucidated several practical challenges, such as long experimental protocols and low signal-to-noise ratios. Here, we used Bayesian optimization—an algorithm well suited to optimizing noisy performance signals with very limited data—to identify the peak and offset timing of hip extension assistance that minimizes the energy expenditure of walking with a textile-based wearable device. Optimal peak and offset timing were found over an average of 21.4 ± 1.0 min and reduced metabolic cost by 17.4 ± 3.2% compared with walking without the device (mean ± SEM), which represents an improvement of more than 60% on metabolic reduction compared with state-of-the-art devices that only assist hip extension. In addition, our results provide evidence for participant-specific metabolic distributions with respect to peak and offset timing and metabolic landscapes, lending support to the hypothesis that individualized control strategies can offer substantial benefits over fixed control strategies. These results also suggest that this method could have practical impact on improving the performance of wearable robotic devices.
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C. J. Payne, et al., “Soft robotic ventricular assist device with septal bracing for therapy of heart failure,” Science Robotics, vol. 2, no. 12, 2017. Publisher's VersionAbstract
Previous soft robotic ventricular assist devices have generally targeted biventricular heart failure and have not engaged the interventricular septum that plays a critical role in blood ejection from the ventricle. We propose implantable soft robotic devices to augment cardiac function in isolated left or right heart failure by applying rhythmic loading to either ventricle. Our devices anchor to the interventricular septum and apply forces to the free wall of the ventricle to cause approximation of the septum and free wall in systole and assist with recoil in diastole. Physiological sensing of the native hemodynamics enables organ-in-the-loop control of these robotic implants for fully autonomous augmentation of heart function. The devices are implanted on the beating heart under echocardiography guidance. We demonstrate the concept on both the right and the left ventricles through in vivo studies in a porcine model. Different heart failure models were used to demonstrate device function across a spectrum of hemodynamic conditions associated with right and left heart failure. These acute in vivo studies demonstrate recovery of blood flow and pressure from the baseline heart failure conditions. Significant reductions in diastolic ventricle pressure were also observed, demonstrating improved filling of the ventricles during diastole, which enables sustainable cardiac output.
O. Atalay, A. Atalay, J. Gafford, and C. J. Walsh, “Highly Sensitive Capacitive-Based Soft Pressure Sensor Based on Conductive Fabric and Micro-porous Dielectric Layer,” Advanced Materials Technologies, 2017. Publisher's VersionAbstract
In this paper, the design and manufacturing of a highly sensitive capacitive-based soft pressure sensor for wearable electronics applications are presented. Toward this aim, two types of soft conductive fabrics (knitted and woven), as well as two types of sacrificial particles (sugar granules and salt crystals) to create micropores within the dielectric layer of the capacitive sensor are evaluated, and the combined effects on the sensor's overall performance are assessed. It is found that a combination of the conductive knit electrode and higher dielectric porosity (generated using the larger sugar granules) yields higher sensitivity (121 × 10−4 kPa−1) due to greater compressibility and the formation of air gaps between silicone elastomer and conductive knit electrode among the other design considerations in this study. As a practical demonstration, the capacitive sensor is embedded into a textile glove for grasp motion monitoring during activities of daily living.