- Graphene Oxide-Enabled Synthesis of Metal Oxide Origamis for Soft Robotics. [Journal Article]
- ANACS Nano 2019 May 28; 13(5):5410-5420
- Origami structures have been widely applied in various technologies especially in the fields of soft robotics. Metal oxides (MOs) have recently emerged as unconventional backbone materials for constr…
Origami structures have been widely applied in various technologies especially in the fields of soft robotics. Metal oxides (MOs) have recently emerged as unconventional backbone materials for constructing complex origamis with distinct functionalities. However, the MO origami structures reported in the literature were rigid and not deformable, thus limiting their applications to soft robotics. Herein, we reported a graphene oxide (GO)-enabled templating synthesis to produce complex MO origami structures from their paper origami templates with high structural replication. The MO origami structures were next stabilized with elastomer, and the MO-elastomer origamis were able to be adapted into multiple actuation systems (including magnetic fields, shape-memory alloys, and pneumatics) for the fabrication of MO origami robots. Compared with conventional paper origami robots, the MO robots were lightweight, mechanically compliant, fire-retardant, magnetic responsive, and power efficient. We further demonstrated the legendary phoenix-fire-reborn concept in the soft robotics fields: a paper origami robot sacrificed itself in a fire scene and transformed itself into a downsized Al2O3 robot; the Al2O3 robot was able to crawl through a narrow tunnel where the original paper robot was unfit. These MO reconfigurable origamis provide an expanded material library for building soft robotics, and the functionalities of MO robots can be systematically engineered via the intercalation of various metal ions during the GO-enabled synthesis.
- Dielectric Elastomer Artificial Muscle: Materials Innovations and Device Explorations. [Journal Article]
- ACAcc Chem Res 2019 Feb 19; 52(2):316-325
- Creating an artificial muscle has been one of the grand challenges of science and engineering. The invention of such a flexible, versatile, and power efficient actuator opens the gate for a new gener…
Creating an artificial muscle has been one of the grand challenges of science and engineering. The invention of such a flexible, versatile, and power efficient actuator opens the gate for a new generation of lightweight, highly efficient, and multifunctional robotics. Many current artificial muscle technologies enable low-power mobile actuators, robots that mimic efficient and natural forms of motion, autonomous robots and sensors, and lightweight wearable technologies. They also have serious applications in biomedical devices, where biocompatibility, from a chemical, flexibility, and force perspective, is crucial. It remains unknown which material will ultimately form the ideal artificial muscle. Anything from shape memory alloys (SMAs) to pneumatics to electroactive polymers (EAPs) realize core aspects of the artificial muscle goal. Among them, EAPs most resemble their biological counterparts, and they encompass both ion-infusion and electric field based actuation mechanisms. Some of the most investigated EAPs are dielectric elastomers (DEs), whose large strains, fracture toughness, and power-to-weight ratios compare favorably with natural muscle. Although dielectric elastomer actuators (DEAs) only entered the artificial muscle conversation in the last 20 years, significant technological progress has reflected their high potential. Research has focused on solving the core issues surrounding DEAs, which includes improving their operational ranges with regard to temperature and voltage, adding new functionality to the materials, and improving the reliability of the components on which they depend. Mechanisms designed to utilize their large-strain actuation and low stiffness has also attracted attention. This Account covers important research by our group and others in various avenues such as decreasing viscoelastic losses in typical DE materials, increasing their dielectric constant, and countering electromechanical instability. We also discuss variable stiffness polymers, specifically bistable electroactive polymers, which, notably, open DEAs to structural applications typically unattainable for soft-actuator technologies. Furthermore, we explore advancements related to highly compliant and transparent electrodes, a crucial component of DEAs capable of achieving high actuation strain. We then cover noteworthy applications, including several novel devices for soft robotics and microfluidics, and how those applications fit within other major developments in the field. Finally, we conclude with a discussion of the remaining challenges facing current DEA technology and speculate on research directions that may further advance DE-based artificial muscles as a whole. This Account serves as a stepping stone into the field of EAPs, which, through the work of researchers worldwide, are positioned as a potential challenger to conventional actuator technologies.
- An Open-Source, Programmable Pneumatic Setup for Operation and Automated Control of Single- and Multi-Layer Microfluidic Devices. [Journal Article]
- HHardwareX 2018; 3:117-134
- Microfluidic technologies have been used across diverse disciplines (e.g. high-throughput biological measurement, fluid physics, laboratory fluid manipulation) but widespread adoption has been limite…
Microfluidic technologies have been used across diverse disciplines (e.g. high-throughput biological measurement, fluid physics, laboratory fluid manipulation) but widespread adoption has been limited in part due to the lack of openly disseminated resources that enable non-specialist labs to make and operate their own devices. Here, we report the open-source build of a pneumatic setup capable of operating both single and multilayer (Quake-style) microfluidic devices with programmable scripting automation. This setup can operate both simple and complex devices with 48 device valve control inputs and 18 sample inputs, with modular design for easy expansion, at a fraction of the cost of similar commercial solutions. We present a detailed step-by-step guide to building the pneumatic instrumentation, as well as instructions for custom device operation using our software, Geppetto, through an easy-to-use GUI for live on-chip valve actuation and a scripting system for experiment automation. We show robust valve actuation with near real-time software feedback and demonstrate use of the setup for high-throughput biochemical measurements on-chip. This open-source setup will enable specialists and novices alike to run microfluidic devices easily in their own laboratories.
- SpiroSurface: A Repulsive and Attractive Force Display for Interactive Tabletops Using a Pneumatic System. [Journal Article]
- ICIEEE Comput Graph Appl 2018 Jul/Aug; 38(4):54-70
- We present SpiroSurface, a novel force display for interactive tabletops. SpiroSurface uses a pneumatic system to generate both repulsive and attractive forces. We develop a prototype with 5x5 grid h…
We present SpiroSurface, a novel force display for interactive tabletops. SpiroSurface uses a pneumatic system to generate both repulsive and attractive forces. We develop a prototype with 5x5 grid holes on the surface connected to an air compressor and vacuum tanks through electromagnetic valves. The display can output a maximum of +1.0 and -0.08 megapascal (MPa) pressure from a hole that generates 74 and -6 N force. We investigated the latency of the output pressure through pneumatics and an experiment, which indicated a minimum of 50-ms latency. The display allows the creation of three kinds of novel interactions: (1) enhancement of GUI, (2) deformation of soft objects, and (3) three-degree-of-freedom rotation of objects. In the first application, users can feel the force from the display without holding or attaching additional devices. In the second and third applications, the shape and motion of an object on the surface can be manipulated without embedding additional active components in the objects. These aspects allow users to easily experience interaction and expand the freedom of interaction design. We introduce several examples combining video projection and motion tracking. These examples demonstrate the potential of the display.
- Precharged Pneumatic Soft Actuators and Their Applications to Untethered Soft Robots. [Journal Article]
- SRSoft Robot 2018; 5(5):567-575
- The past decade has witnessed tremendous progress in soft robotics. Unlike most pneumatic-based methods, we present a new approach to soft robot design based on precharged pneumatics (PCP). We propos…
The past decade has witnessed tremendous progress in soft robotics. Unlike most pneumatic-based methods, we present a new approach to soft robot design based on precharged pneumatics (PCP). We propose a PCP soft bending actuator, which is actuated by precharged air pressure and retracted by inextensible tendons. By pulling or releasing the tendons, the air pressure in the soft actuator is modulated, and hence, its bending angle. The tendons serve in a way similar to pressure-regulating valves that are used in typical pneumatic systems. The linear motion of tendons is transduced into complex motion via the prepressurized bent soft actuator. Furthermore, since a PCP actuator does not need any gas supply, complicated pneumatic control systems used in traditional soft robotics are eliminated. This facilitates the development of compact untethered autonomous soft robots for various applications. Both theoretical modeling and experimental validation have been conducted on a sample PCP soft actuator design. A fully untethered autonomous quadrupedal soft robot and a soft gripper have been developed to demonstrate the superiority of the proposed approach over traditional pneumatic-driven soft robots.
- Ellipsometry-based combination of isothermal sorption-desorption measurement and temperature programmed desorption technique: A probe for interaction of thin polymer films with solvent vapor. [Journal Article]
- RSRev Sci Instrum 2018; 89(5):055114
- An environmental chamber equipped with an in situ spectroscopic ellipsometer, programmatic vapor pressure control, and variable temperature substrate holder has been designed for studying polymer coa…
An environmental chamber equipped with an in situ spectroscopic ellipsometer, programmatic vapor pressure control, and variable temperature substrate holder has been designed for studying polymer coating behavior during an exposure to a solvent vapor and also for probing the residual solvent in the film afterwards. Both sorption-desorption cycle at a constant temperature and temperature programmed desorption (TPD) of the residual solvent manifest themselves as a change of the film thickness. Monitoring of ellipsometric angles of the coating allows us to determine the thickness as a function of the vapor pressure or sample temperature. The solvent vapor pressure is precisely regulated by a computer-controlled pneumatics. TPD spectra are recorded during heating of the film in an oil-free vacuum. The vapor pressure control system is described in detail. The system has been tested on 6-170 nm thick polystyrene, poly(methyl methacrylate), and poly(2-vinyl pyridine) films deposited on silicon substrates. Liquid toluene, water, ethanol, isopropanol, cyclohexane, 1,2-dichloroethane, and chlorobenzene were used to create a vapor atmosphere. Typical sorption-desorption and TPD curves are shown. The instrument achieves sub-monolayer sensitivity for adsorption studies on flat surfaces. Polymer-solvent vapor systems with strong interaction demonstrate characteristic absorption-desorption hysteresis spanning from vacuum to the glass transition pressure. Features on the TPD curves can be classified as either glass transition related film contraction or low temperature broad contraction peak. Typical absorption-desorption and TPD dependencies recorded for the 6 nm thick polystyrene film demonstrate the possibility to apply the presented technique for probing size effects in extremely thin coatings.
- Stormram 4: An MR Safe Robotic System for Breast Biopsy. [Journal Article]
- ABAnn Biomed Eng 2018; 46(10):1686-1696
- Suspicious lesions in the breast that are only visible on magnetic resonance imaging (MRI) need to be biopsied under MR guidance with high accuracy and efficiency for accurate diagnosis. The aim of t…
Suspicious lesions in the breast that are only visible on magnetic resonance imaging (MRI) need to be biopsied under MR guidance with high accuracy and efficiency for accurate diagnosis. The aim of this study is to present a novel robotic system, the Stormram 4, and to perform preclinical tests in an MRI environment. Excluding racks and needle, its dimensions are 72 × 51 × 40 mm. The Stormram 4 is driven by two linear and two curved pneumatic stepper motors. The linear motor is capable of exerting 63 N of force at a pressure of 0.65 MPa. In an MRI environment the maximum observed stepping frequency is 30 Hz (unloaded), or 8 Hz when full force is needed. The Stormram 4's mean positioning error is 0.73 ± 0.47 mm in free air, and 1.29 ± 0.59 mm when targeting breast phantoms in MRI. Excluding the off-the-shelf needle, the robot is inherently MR safe. The robot is able to accurately target lesions under MRI guidance, reducing tissue damage and risk of false negatives. These results are promising for clinical experiments, improving the quality of healthcare in the field of MRI-guided breast biopsies.
- Arthrobots. [Journal Article]
- SRSoft Robot 2017; 4(3):183-190
- This article describes a class of robots-"arthrobots"-inspired, in part, by the musculoskeletal system of arthropods (spiders and insects, inter alia). Arthrobots combine mechanical compliance, light…
This article describes a class of robots-"arthrobots"-inspired, in part, by the musculoskeletal system of arthropods (spiders and insects, inter alia). Arthrobots combine mechanical compliance, lightweight and simple construction, and inexpensive yet scalable design. An exoskeleton, constructed from thin organic polymeric tubes, provides lightweight structural support. Pneumatic joints modeled after the hydrostatic joints of spiders provide actuation and inherent mechanical compliance to external forces. An inflatable elastomeric tube (a "balloon") enables active extension of a limb; an opposing elastic tendon enables passive retraction. A variety of robots constructed from these structural elements demonstrate (i) crawling with one or two limbs, (ii) walking with four or six limbs (including an insect-like triangular gait), (iii) walking with eight limbs, or (iv) floating and rowing on the surface of water. Arthrobots are simple to fabricate and are able to operate safely in contact with humans.
- Using Voice Coils to Actuate Modular Soft Robots: Wormbot, an Example. [Journal Article]
- SRSoft Robot 2016 Dec 01; 3(4):198-204
- In this study, we present a modular worm-like robot, which utilizes voice coils as a new paradigm in soft robot actuation. Drive electronics are incorporated into the actuators, providing a significa…
In this study, we present a modular worm-like robot, which utilizes voice coils as a new paradigm in soft robot actuation. Drive electronics are incorporated into the actuators, providing a significant improvement in self-sufficiency when compared with existing soft robot actuation modes such as pneumatics or hydraulics. The body plan of this robot is inspired by the phylum Annelida and consists of three-dimensional printed voice coil actuators, which are connected by flexible silicone membranes. Each electromagnetic actuator engages with its neighbor to compress or extend the membrane of each segment, and the sequence in which they are actuated results in an earthworm-inspired peristaltic motion. We find that a minimum of three segments is required for locomotion, but due to our modular design, robots of any length can be quickly and easily assembled. In addition to actuation, voice coils provide audio input and output capabilities. We demonstrate transmission of data between segments by high-frequency carrier waves and, using a similar mechanism, we note that the passing of power between coupled coils in neighboring modules-or from an external power source-is also possible. Voice coils are a convenient multifunctional alternative to existing soft robot actuators. Their self-contained nature and ability to communicate with each other are ideal for modular robotics, and the additional functionality of sound input/output and power transfer will become increasingly useful as soft robots begin the transition from early proof-of-concept systems toward fully functional and highly integrated robotic systems.
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- Disposable Fluidic Actuators for Miniature In-Vivo Surgical Robotics. [Journal Article]
- JMJ Med Device 2017; 11(1):0110031-110038
- Fusion of robotics and minimally invasive surgery (MIS) has created new opportunities to develop diagnostic and therapeutic tools. Surgical robotics is advancing from externally actuated systems to m…
Fusion of robotics and minimally invasive surgery (MIS) has created new opportunities to develop diagnostic and therapeutic tools. Surgical robotics is advancing from externally actuated systems to miniature in-vivo robotics. However, with miniaturization of electric-motor-driven surgical robots, there comes a trade-off between the size of the robot and its capability. Slow actuation, low load capacity, sterilization difficulties, leaking electricity and transferring produced heat to tissues, and high cost are among the key limitations of the use of electric motors in in-vivo applications. Fluid power in the form of hydraulics or pneumatics has a long history in driving many industrial devices and could be exploited to circumvent these limitations. High power density and good compatibility with the in-vivo environment are the key advantages of fluid power over electric motors when it comes to in-vivo applications. However, fabrication of hydraulic/pneumatic actuators within the desired size and pressure range required for in-vivo surgical robotic applications poses new challenges. Sealing these types of miniature actuators at operating pressures requires obtaining very fine surface finishes which is difficult and costly. The research described here presents design, fabrication, and testing of a hydraulic/pneumatic double-acting cylinder, a limited-motion vane motor, and a balloon-actuated laparoscopic grasper. These actuators are small, seal-less, easy to fabricate, disposable, and inexpensive, thus ideal for single-use in-vivo applications. To demonstrate the ability of these actuators to drive robotic joints, they were modified and integrated in a robotic arm. The design and testing of this surgical robotic arm are presented to validate the concept of fluid-power actuators for in-vivo applications.