FABRIC STRETCH SENSOR FAQS
Fabric Stretch Sensors are excellent devices for creating wearable technology applications, as we can use them to monitor human body motion and shape. To learn more about them, download our eGuide — or visit the buy a kit page.
What are Fabric Stretch Sensors used for?
We use Fabric Stretch Sensors to turn analog motion to digital data. With this data, we can visualize and record human body movement. Sewing stretch sensors into form-fitting clothing allows us to establish a mutual relationship between the movement of the joint and the movement of a sensor (or sensors) placed on that joint. We can then model the results using a mathematical equation curve fit relationship, and use this model to create an application. For more on characterization, check out our blog How to Measure Joint Angle with Stretch Sensors.
How can I connect the sensor to a custom app that I will build?
Once you’re ready to build your own mobile app, we have two API Libraries to help simplify the process — one for Android and one for iOS. The APIs demonstrate how to establish a connection between one or more StretchSense Fabric Evaluation circuits and a BLE-enabled mobile device. They are available on StretchSense’s GitHub page here.
What other platforms do you have APIs for?
We also have API libraries containing example projects for Arduino and MacOS. If you or your team would like to experiment with our API Libraries, just fork the repository of your choice here and check out the documentation.
Can the stretch sensors be integrated with LabVIEW?
We have created a StretchSense Development VI to make the integration of our technology as user-friendly as possible. Two versions of our LabVIEW Development VI are available. One uses a USB-Bluetooth dongle to enable your PC to communicate with the StretchSense Sensor Module, while the other uses the built-in Bluetooth module of your PC (additional drivers may need to be installed depending on the version used). Our VI can be easily expanded to include application-specific functions or integrated into larger VIs. For more detailed instructions, check out the LabVIEW Development VI Information Sheet.
Are the sensors affected by changes in temperature?
Our sensors will be affected to a small extent by some temperature changes, but this effect is less apparent than in many other sensors. This is due to capacitor technology being most dependent on geometry, not temperature. These small changes can be accounted for by using a reference sensor, which represents the sensor’s true length profile.
How far can the Fabric Stretch Sensors be stretched?
Our Fabric Stretch Sensors have a maximum extension of 80mm (80% strain of their active area). Once they have extended to this length, they strainlock (i.e. cannot be stretched any further). This ensures they are always operating within their strain limits and prevents them from being damaged by overstretching.
Are the sensors machine washable?
Our Fabric Stretch Sensors are not machine washable.
What kind of fabric is the sensor made out of?
Our current Fabric Stretch Sensors are made from a conductive fabric. It is also possible to manufacture them from a non-conductive fabric depending on your specific application needs.
Why is shielding important?
Shielding is important as it protects the sensors from electrical noise. This noise interferes with the signal by introducing random fluctuations. Without shielding, filtering is needed in order to interpret the signal. This not only adds another layer of complexity to the system, but also delays the signal communication.
What circuits can the Fabric Stretch Sensors be used with and what is the sampling rate?
Fabric Stretch Sensors can be connected to a StretchSense BLE circuit or a High Power 10-Channel SPI sensing circuit. With a BLE circuit, sensors can be sampled at 25-30Hz per channel, but with wired circuits, the sample rate is up to 1,000Hz per channel.
How sensitive are the Fabric Stretch Sensors?
Our Fabric Stretch Sensors have a sensitivity of 3.82pF/mm allowing for incredibly precise measurements.
Can I measure forces with the Fabric Stretch Sensors?
Our Fabric Stretch Sensors are designed to measure how much they have stretched (i.e. the shape change), not the force that has caused the deformation. While Fabric Stretch Sensors can be used to measure forces, we recommend using our compression sensors instead as they are mechanically optimised for measuring interface forces between soft objects.
How do I mount the Fabric Stretch Sensors so that they accurately measure body motion?
Our Fabric Stretch Sensors generate the best results when attached to close-fitting garments that allow the sensors to follow body motion precisely. Correct mounting of the sensors is very important as sensors attached to loose or ill-fitting clothing will generate inaccurate results.
Thanks for reading. We hope some of your questions have been answered. If you have any more please get in touch here to speak to one of our experts.