We describe the design and control of a wearable robotic device powered by pneumatic artificial muscle actuators for use in ankle–foot rehabilitation. The design is inspired by the biological musculoskeletal system of the human foot and lower leg, mimicking the morphology and the functionality of the biological muscle–tendon–ligament structure. A key feature of the device is its soft structure that provides active assistance without restricting natural degrees of freedom at the ankle joint. Four pneumatic artificial muscles assist dorsiflexion and plantarflexion as well as inversion and eversion. The prototype is also equipped with various embedded sensors for gait pattern analysis. For the subject tested, the prototype is capable of generating an ankle range of motion of 27 ◦ (14 ◦ dorsiflexion and 13 ◦ plantarflexion). The controllability of the system is experimentally demonstrated using a linear time-invariant (LTI) controller. The controller is found using an identified LTI model of the system, resulting from the interaction of the soft orthotic device with a human leg, and model-based classical control design techniques. The suitability of the proposed control strategy is demonstrated with several angle-reference following experiments.

/pdf/design-and-control-of-a-bio-inspired-soft-wearable-robotic-110pb507k2.pdf

Design and control of a bio-inspired soft wearable robotic device for ankle-foot rehabilitation.

Abstract The emergence of silicon photonics over the past two decades has established silicon as a preferred substrate platform for photonic integration. While most silicon-based photonic components have so far been realized in the near-infrared (near-IR) telecommunication bands, the mid-infrared (mid-IR, 2–20-μm wavelength) band presents a significant growth opportunity for integrated photonics. In this review, we offer our perspective on the burgeoning field of mid-IR integrated photonics on silicon. A comprehensive survey on the state-of-the-art of key photonic devices such as waveguides, light sources, modulators, and detectors is presented. Furthermore, on-chip spectroscopic chemical sensing is quantitatively analyzed as an example of mid-IR photonic system integration based on these basic building blocks, and the constituent component choices are discussed and contrasted in the context of system performance and integration technologies.

/pdf/mid-infrared-integrated-photonics-on-silicon-a-perspective-31psns51w2.pdf

Mid-infrared integrated photonics on silicon: a perspective

Soft robotics offers the unique promise of creating inherently safe and adaptive systems. These systems bring man-made machines closer to the natural capabilities of biological systems. An important requirement to enable self-contained soft mobile robots is an on-board power source. In this paper, we present an approach to create a bio-inspired soft robotic snake that can undulate in a similar way to its biological counterpart using pressure for actuation power, without human intervention. With this approach, we develop an autonomous soft snake robot with on-board actuation, power, computation and control capabilities. The robot consists of four bidirectional fluidic elastomer actuators in series to create a traveling curvature wave from head to tail along its body. Passive wheels between segments generate the necessary frictional anisotropy for forward locomotion. It takes 14 h to build the soft robotic snake, which can attain an average locomotion speed of 19 mm s−1.

/pdf/autonomous-undulatory-serpentine-locomotion-utilizing-body-y0zmf8ncjg.pdf

Autonomous undulatory serpentine locomotion utilizing body dynamics of a fluidic soft robot

This paper introduces a novel, bioinspired manipulator for minimally invasive surgery (MIS). The manipulator is entirely composed of soft materials, and it has been designed to provide similar motion capabilities as the octopus's arm in order to reach the surgical target while exploiting its whole length to actively interact with the biological structures. The manipulator is composed of two identical modules (each of them can be controlled independently) with multi-directional bending and stiffening capabilities, like an octopus arm. In the authors' previous works, the design of the single module has been addressed. Here a two-module manipulator is presented, with the final aim of demonstrating the enhanced capabilities that such a structure can have in comparison with rigid surgical tools currently employed in MIS. The performances in terms of workspace, stiffening capabilities, and generated forces are characterized through experimental tests. The combination of stiffening capabilities and manipulation tasks is also addressed to confirm the manipulator potential employment in a real surgical scenario.

https://iopscience.iop.org/article/10.1088/1748-3190/10/3/035008/pdf

A bioinspired soft manipulator for minimally invasive surgery.

https://iopscience.iop.org/article/10.1088/1468-6996/15/1/014603/pdf

Mid-infrared materials and devices on a Si platform for optical sensing

We have demonstrated what we believe to be the first waveguide photonic crystal cavity operating in the mid-infrared. The devices were fabricated from Ge23Sb7S70 chalcogenide glass (ChG) on CaF2 substrates by combing photolithographic patterning and focused ion beam milling. The waveguide-coupled cavities were characterized using a fiber end fire coupling method at 5.2 μm wavelength, and a loaded quality factor of ~2000 was measured near the critical coupling regime.

http://web.mit.edu/people/hujuejun/My%20Papers/Journal%20Papers/Demonstration%20of%20mid-infrared%20waveguide%20photonic%20crystal%20cavities.pdf

Demonstration of mid-infrared waveguide photonic crystal cavities

Reaction bonded SiC/Si (RBSC) ceramic composites have been extensively used in applications calling for outstanding mechanical and thermal properties such as high energy laser (HEL) mirrors, advanced armors and semiconductor fabrication platforms. The phase components of RBSC generally include preexisting α-SiC, reaction formed β-SiC, and residual crystalline silicon (c-Si). In addition, however, a minor phase, amorphous Si (a-Si), is often observed near the SiC/Si interface due to local temperature and structural fluctuations that can occur during the composite fabrication. An in-situ tensile testing system composed of piezo stages, force sensor and specimen holders is integrated and accommodated inside a field emission scanning electron microscope (FE-SEM) for the nanoscale tensile testing. Tensile specimens containing the SiC/Si interface are successfully prepared by focused ion beam (FIB). The interfacial tensile strength is directly measured for the first time and it reaches as high as 7.1 GPa. The a-Si phase on the fracture surfaces is confirmed by high resolution transmission electron microscopy (HRTEM).

In-situ measurement of SiC/Si interfacial tensile strength of reaction bonded SiC/Si composite

Study of tensile properties of multiwalled carbon nanotube/polyether ether ketone polymer composites at the nanoscale

We have demonstrated what we believe to be the first waveguide photonic crystal cavity operating in the mid-infrared. The devices were fabricated from Ge23Sb7S70 chalcogenide glass on CaF2 substrates by combing photolithographic patterning and focus ion beam milling. The waveguide-coupled cavities were characterized using a fiber end fire coupling method at 5.2 {\mu}m wavelength, and a loaded quality factor of ~ 2,000 was measured near the critical coupling regime.

Fei Deng

Papers

Mid-infrared materials and devices on a Si platform for optical sensing

Demonstration of mid-infrared waveguide photonic crystal cavities

In-situ measurement of SiC/Si interfacial tensile strength of reaction bonded SiC/Si composite

Study of tensile properties of multiwalled carbon nanotube/polyether ether ketone polymer composites at the nanoscale

Demonstration of mid-infrared waveguide photonic crystal cavities