Jul 142017
 

The silicone-textile hybrid sensors are highly flexible and resilient, making them excellent candidates for sensing body movement. Credit: Wyss Institute at Harvard University

Hybrid silicone-fabric sensor detects fine motor movements by flexing with the body

Wearable technologies – from heart rate monitors to virtual reality headsets – are exploding in popularity in both the consumer and research spaces, but most of the electronic sensors that detect and transmit data from wearables are made of hard, inflexible materials that can restrict both the wearer’s natural movements and the accuracy of the data collected. Now, a team of researchers at the Wyss Institute for Biologically Inspired Engineering and the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) has created a highly sensitive soft capacitive sensor made of silicone and fabric that moves and flexes with the human body to unobtrusively and accurately detect movement.

“We’re really excited about this sensor because, by leveraging textiles in its construction, it is inherently suitable for integration with fabric to make ‘smart’ robotic apparel,” says corresponding author Conor Walsh, Ph.D., Core Faculty member at the Wyss Institute and the John L. Loeb Associate Professor of Engineering and Applied Sciences at SEAS. “Additionally, we have designed a unique batch-manufacturing process that allows us to create custom-shaped sensors that share uniform properties, making it possible to quickly fabricate them for a given application,” says co-author Ozgur Atalay, Ph.D., Postdoctoral Fellow at the Wyss Institute. This research is published in the current issue of Advanced Materials Technologies, and the protocol is available as part of the Harvard Biodesign Lab’s Soft Robotics Toolkit.

The Wyss team’s technology consists of a thin sheet of silicone (a poorly conductive material) sandwiched between two layers of silver-plated, conductive fabric (a highly conductive material), forming a capacitive sensor. This type of sensor registers movement by measuring the change in capacitance, or the ability to hold electrical charge, of the electrical field between the two electrodes. “When we apply strain by pulling on the sensor from the ends, the silicone layer gets thinner and the conductive fabric layers get closer together, which changes the capacitance of the sensor in a way that’s proportional to the amount of strain applied, so we can measure how much the sensor is changing shape,” explains co-author Daniel Vogt, Research Engineer at the Wyss Institute.

This prototype glove includes soft sensors that are capable of registering movement of each finger individually. Credit: Wyss Institute at Harvard University

The hybrid sensor’s superior performance stems from its novel manufacturing process, in which the fabric is attached to both sides of the silicone core with an additional layer of liquid silicone that is subsequently cured. This method allows the silicone to fill some of the air gaps in the fabric, mechanically locking it to the silicone and increasing the surface area available for distributing strain and storing electrical charge. This silicone-textile hybrid improves sensitivity to movement by capitalizing on the qualities of both materials: the strong, interlocking fabric fibers help limit how much the silicone deforms while stretching, and the silicone helps the fabric return to its original shape after strain is removed. Finally, thin, flexible wires are permanently attached to the conductive fabric with thermal seam tape, allowing electrical information from the sensor to be transmitted to a circuit without a hard, bulky interface.

The team evaluated their new sensor design by performing strain experiments in which various measurements are taken as the sensor is stretched by an electromechanical tester. Generally, as an elastic material is pulled, its length increases while its thickness and width decrease, so the total area of the material – and, therefore, its capacitance – stays constant. Surprisingly, the researchers found that the conductive area of their sensor increased as it was stretched, resulting in greater-than-expected capacitance. “Silicone-based capacitive sensors have limited sensitivity based on the nature of material. Embedding the silicone in conductive fabric, however, created a matrix that prevented the silicone from shrinking as much width-wise, which improved sensitivity above that of the bare silicone we tested,” says lead author Asli Atalay, Postdoctoral Fellow at the Wyss Institute.

The hybrid sensor detected increases in capacitance within 30 milliseconds of strain application and physical changes of less than half a millimeter, confirming that it is capable of capturing movement on the scale of the human body. To test that ability in a real-world scenario, the team integrated a set of them into a glove to measure fine-motor hand and finger movements in real time. The sensors were successfully able to detect capacitance changes on individual fingers as they moved, indicating their relative positions over time. “Our sensor’s greater sensitivity means it has the ability to distinguish smaller movements, like slightly moving one finger side-to-side rather than simply whether the whole hand is open or clenched in a fist,” explains co-author Vanessa Sanchez, a Graduate Student in the Biodesign Lab at SEAS.

This textile-based sensor effectively registers fine motor movements of the human body, taking researchers one step closer to creating soft, wearable robots. Credit: Wyss Institute at Harvard University

While this study is a preliminary proof-of-concept, the team is excited about the many future directions in which this technology could develop. “This work represents our growing interest in leveraging textile technology in robotic systems, and we see promising applications for motion capture ‘in the wild,’ such as athletic clothing that tracks physical performance or soft clinical devices to monitor patients in their homes. In addition, when combined with fabric-based soft actuators, these sensors will enable new robotic systems that truly mimic apparel,” says Walsh.

“This technology opens up entirely new approaches to wearable diagnostics and coupled therapeutics that undoubtedly will pay a central role in the future of home healthcare.

Learn more: Soft and stretchy fabric-based sensors for wearable robots

 

The Latest on: Smart robotic apparel
  • Fabric-based sensors for wearable robots
    on July 28, 2017 at 7:30 am

    “We’re really excited about this sensor because, by leveraging textiles in its construction, it is inherently suitable for integration with fabric to make ‘smart’ robotic apparel,” said corresponding author Conor Walsh, PhD, Core Faculty member ... […]

  • How to Keep a Roomba Vacuum Cleaner From Collecting Data About Your Home
    on July 26, 2017 at 2:42 pm

    In an interview with Reuters published yesterday, iRobot CEO Colin Angle suggested his company might one day sell the mapping data collected by Roomba robotic vacuum cleaners ... of things and services that the smart home can deliver once you have a ... […]

  • Robot vacum cleaner could collect data about users’ homes
    on July 25, 2017 at 10:30 am

    The maker of the Roomba robotic vacuum ... things and services that the smart home can deliver once you have a rich map of the home that the user has allowed to be shared,” Angle told Reuters. An old-fashioned candy shop will open in the heart of ... […]

  • BizVibe Announces a New B2B Networking Platform for the Industrial Machinery and Machine Parts Industry
    on July 24, 2017 at 11:59 am

    This is the latest focus industry of the networking platform, in addition to textiles and apparel, automobiles, electronics and telecom, and others. This Smart News Release features ... As automation and robotics become more involved in the manufacturing ... […]

  • Industrial Robotics Market Growing at a CAGR of 9.60% During 2017 to 2023 - ReportsnReports
    on July 19, 2017 at 9:26 pm

    textiles and clothing; supply chain management; and wood). Lastly, the global industrial robotics market is segmented into 4regions-north America, Europe, APAC, and RoW. The report would help the market leaders/new entrants in this market in the following ... […]

  • Smart robotic apparel gets flexible with a hybrid silicone-fabric sensor
    on July 13, 2017 at 5:00 pm

    Wearable technologies – from heart rate monitors to virtual reality headsets – are exploding in popularity in both the consumer and research spaces, but most of the electronic sensors that detect and transmit data from wearables are made of hard ... […]

  • Computerized Fabric That Can Turn “Any Piece of Clothing into a Fitness Tracker”
    on July 13, 2017 at 3:43 pm

    It will put the hard, inflexible material to shame. A highly sensitive soft sensor, it leverages textiles in its construction, and when integrated with fabric it becomes a smart robotic apparel. Tackling the hard, inflexible material properties usually ... […]

  • Smart Clothing and the Future of Apparel
    on July 5, 2017 at 7:57 am

    While you were enjoying the clean, elemental high of your trail run, your smart ... California Apparel News that 2017 SoftWear sales are forecast to beat 2016’s numbers four times over. Also interesting: he and other proponents of robotic automation ... […]

  • Why Smart Manufacturing Is Guaranteed to Need Industrial Robotics
    on June 15, 2017 at 1:37 am

    Although many companies have been hesitant to embrace the robotic production line ... a device on the other side of the shop, thereby sharing production metrics or transmitting last-minute production changes. Today's smart equipment can even learn how ... […]

  • Robotics, Smart Materials, and their Future Impact for Humans
    on April 6, 2017 at 12:55 pm

    However, there is no need for a robot to be humanoid, to have limbs, to walk, or to talk. Rather, we can have a much wider interpretation of what a robot is. The boundaries between smart materials ... the form of power-assist clothing that will restore ... […]

via Google News and Bing News

Other Interesting Posts

Leave a Reply

%d bloggers like this: