3D printing of soft fluidic actuators with graded porosity

Willemstein, Nick; Kooij, Herman van der; Sadeghi, Alì

doi:10.1039/d2sm00524g

Cited by 6 publications

(8 citation statements)

References 35 publications

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“…The sensing was implemented using the other two layers by adding piezoresistive porous (foam-like) sensors. These piezoresistive sensors 18,19,20 change their resistance when subjected to a load. The resistance of the sensors was measured using a voltage divider (see Fig.…”

Section: Soft Sensorized Insole Design and Force Estimation Methodsmentioning

confidence: 99%

“…This behavior needs to be compensated for to estimate the ground reaction forces more accurately. In literature, people solve this by using a model-based compensation, such as a Hammerstein-Wiener (HW) model 18,21 , training a neural network 22 and/or other machine learning tools 23 . Within this work, the HW model is employed as it is simple yet able to provide good force estimates, as seen in 21 .…”

Section: Soft Sensorized Insole Design and Force Estimation Methodsmentioning

confidence: 99%

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3D Printed Graded Porous Sensors for Soft Sensorized Insoles with Gait Phase & Ground Reaction Forces Estimation

Willemstein¹,

Sridar²,

Kooij³

et al. 2023

Preprint

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Sensorized insoles provide a tool to perform gait studies and health monitoring during daily life. These sensorized insoles need to be comfortable and lightweight to be accepted. Previous work has already demonstrated that sensorized insoles are possible and can estimate both ground reaction force and gait cycle. However, these are often assemblies of commercial components restricting design freedom and flexibility. Within this work, we investigate the feasibility of using four 3D-printed porous (foam-like) piezoresistive sensors embedded in a commercial insole. These sensors were evaluated using an instrumented treadmill as the golden standard. It was observed that the four sensors behaved in line with the expected change in pressure distribution during the gait cycle. In addition, Hammerstein-Wiener models were identified that were capable of estimating the vertical and mediolateral ground reaction forces (GRFs). Their NRMSE fits were on average 82% and 73%, respectively. Similarly, for the averaged gait cycle the R 2 values were 0.98 and 0.99 with normalized RMS errors overall below 6%. These values were comparable with other insoles based on commercial force sensing resistors but at a significantly lower cost (over four times cheaper). Thereby indicating that our 3D-printed sensors can be an interesting option for sensorized insoles. The advantage of 3D printing these sensors is that it allows for significantly more design freedom, reduces assembly, and is cheaper. However, further research is needed to exploit this design freedom for complex sensors, estimate the anteroposterior GRF, and fully 3D print the entire insole.

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Section: Soft Sensorized Insole Design and Force Estimation Methodsmentioning

confidence: 99%

Section: Soft Sensorized Insole Design and Force Estimation Methodsmentioning

confidence: 99%

3D Printed Graded Porous Sensors for Soft Sensorized Insoles with Gait Phase & Ground Reaction Forces Estimation

Willemstein¹,

Sridar²,

Kooij³

et al. 2023

Preprint

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Section: Introductionmentioning

confidence: 99%

“…The user's gripping abilities were significantly improved by the hybrid assistive, exoskeleton glove, which could apply the pressures necessary to carry out a variety of daily chores. Also, Willemstein et al 37 printed a soft actuator by a coiling liquid rope and the infill foam approach for printing structures with variable porosities. The use of this grading allowed for the realisation of rectangular constructions with a variety of deformation patterns, including twisting, contracting, and bending.…”

Section: Introductionmentioning

confidence: 99%

Shape memory meta-laminar jamming actuators fabricated by 4D printing

Dezaki

Bodaghi

2023

Soft Matter

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“…For example, functionally graded and damage-tolerant end effectors have been designed for puncturing and anchoring into solid substrates. [13] Stiffness graded materials have been achieved through multimaterial additive manufacturing approaches [13,14] and 3D-printed graded porous structures, [15] which, although not directly replacing the hard-soft interface, employ material structures to distribute stress over many separate discrete interfaces. Recently, smoother stiffness gradients were achieved by controlled solution mixing and extrusion of cellulose-based materials to generate mechanically programmable sheets.…”

Section: Introductionmentioning

confidence: 99%

Stiffness Graded Electroactive Artificial Muscle

Taghavi

Conn

Rossiter

2022

Adv Funct Materials

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In nature, hydrostatic, endo-and exo-skeletons are widely observed, and provide essential rigidity and anchoring points for the application of muscular forces. The efficient interface between a hard skeleton and soft muscle in biology is made possible by a complex hierarchy of structures and composite materials, extending from the nano-to the meso-scale. In contrast, artificial constructs that aim to bridge this hard-soft interface are prone to failure due to local discontinuities and concentrations in stress and strain which lead to material ruptures, delamination, and tearing. In this article, the concept of a stiffness-graded electroactive material is proposed which emulates the softrigid interface in the nature biological systems and provides both electromechanical activity and the smooth stiffness gradient needed to bridge these two extreme states. This is achieved by programming the diffusion of a rigid filler material (polyvinyl chloride) in a liquid plasticizer (diisodecyl adipate). It is shown that the resulting stiffness gradient can match that of biological tissues such as smooth and skeletal muscles, and that the distal rigid region can be drilled and bonded and significant loads can be safely applied. Additionally, the resulting composite shows electroactive capability through graded anodophilic actuation characteristics. This protocol can be extended to numerous morphologies such as vertical or radial gradients depending on the deployment of two precursor ingredients. Finally, example applications including surface morphing and motion generation are demonstrated. The embodied stiffness gradient and electroactivity make this concept suitable for the development of bio-integrating and wearable artificial muscles systems and more effective soft robots.

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3D printing of soft fluidic actuators with graded porosity

Abstract: New additive manufacturing methods are needed to realize more complex soft robots. One example is soft fluidic robotics, which exploits fluidic power and stiffness gradients. Porous structures are an interesting...

Cited by 6 publications

References 35 publications

3D Printed Graded Porous Sensors for Soft Sensorized Insoles with Gait Phase & Ground Reaction Forces Estimation

3D Printed Graded Porous Sensors for Soft Sensorized Insoles with Gait Phase & Ground Reaction Forces Estimation

Shape memory meta-laminar jamming actuators fabricated by 4D printing

Stiffness Graded Electroactive Artificial Muscle

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