To measure the. human body, sensors need to be soft and precise SOFT HARD

Size: px

Start display at page:

Download "To measure the. human body, sensors need to be soft and precise SOFT HARD"

Jodie Johns
6 years ago
Views:

1 Technology Overview

2 To measure the SOFT human body, sensors need to be soft and precise IMPRECISE PRECISE HARD

3 They need to be unobtrusive so they can disappear into clothing SERIAL AND BLUETOOTH LE COMMS ULTRA THIN FLEXIBLE STRETCHABLE FLEXIBLE HIGHLY TUNABLE STIFFNESS & STRETCH PRECISE DURABLE TOUGH SEWABLE INTO TEXTILES FULLY ENCAPSULATED

4 HOW DOES STRETCHSENSE TECHNOLOGY WORK?

5 We use stretchable elastic capacitors for soft precise sensing and energy harvesting Stretchable Dielectric + Highly elastic electrically Conductive electrodes STRETCH RELAX + The sensors are elastic with high resilience and return to their original shape when released We measure sensor capacitance which changes with stretch Capacitance is proportional to Area Thickness The sensors are volumetrically incompressible, so if one is stretched long its length Area increases and Thickness decreases, both of which contribute to an increase in capacitance

6 The sensor measures its own deformation whether you stretch it or squeeze it STRETCH MODE Dielectric REFERENCE STATE Electrodes PRESSURE MODE

7 We use stretchable elastic capacitors for soft precise sensing and energy harvesting TECHNOLOGY MATERIAL PARAMETERS PROS CONS Resistive n Resistivity of stretch material (t) n Sensor geometry (Length, cross section Area R = tl A Inexpensive n t highly sensitivity to: - Time - Temp - Strain rate Low resolution, high drift, complex non-linear behaviour n Dielectric Constant (f) n f insensitive to time, strain, strain rate Capacitive n Sensor geometry (Length, Width, Thickness) C = flw S n Low temp and moisture sensitivity that can be eliminated with ref sensor n C tightly correlated with geometry Computationally intensive Precise, repeatable, stable deformation sensor

8 NASA independently tested our fabric stretch sensor against a range of resistive options Litteken, Douglas A. (2017); Evaluation of Strain Measurement Devices or Inflatable Structures; AIAA SciTech 2017 (Grapevine, Texas), Jan

9 Stretch sensors need a quality circuit Ten years of circuit development means Low latency Algorithms that are fast and robust Options to maximise sampling rate for high performance, or minimise CPU time for low power Precise, repeatable outputs in SI units

10 The combination of StretchSense sensors + algorithms provide accurate and repeatable results Capitance (pf) TYPICAL CAPACITANCE EXTENSION CURVE Extension (mm) High Strain: 200% engineering strain High Repeatability: < 0.67 pf/mm High Linearity: < 0.7 pf Stable Rest Capacitance: 365 pf average High sensitivity: 2.8 pf/mm average Measurement insensitive to time, strain level, strain rate Low sensitivity to temperature and humidity average

11 Create a customized sensing solution We can tailor to your needs Registration with the device/body Sensor mechanics (material selection) Data logging and storage Machine Learning Data Analysis SENSOR SHAPE Length Width Thickness Sensor design (rest capacitance + DATA geometry/area/number of layers + interconnects) Interrogation circuit performance Heat press glueing Sewing Fasteners SENSOR PROPERTIES Washability Sensitivity Materials Environmental Data interpretation INTEGRATION Size Power consumtion Wired / wireless Number of sensors Sampling Rate ELECTRONICS

12 We will tune the sensitivity of a sensor to meet your requirements Through sensor design W Electrodes Dielectric and matching T DIRECTION OF STRETCH electronics L For a given displacement, the sensitivity of a sensor is Proportional to W (larger W = more sensitive) Proportional to the Number of Dielectric Layers, N (more layers = more sensitive) Inversely Proportional to T (smaller T = more sensitive)

and low speed No bulky/complicated intermediary mechanisms required

13 With the addition of energy harvesting, sensing systems can become self-powered Driven by human movement Works at large displacement and low speed No bulky/complicated intermediary mechanisms required Is hidden in clothes or shoes POWER INTO KNOWLEDGE MOVEMENT INTO POWEW

14 Soft, unobtrusive energy harvesting to eliminate the hassle of charging wearables

15 We turn the stretching of clothing or the THE ENERGY HARVESTING CYCLE compression of shoe soles into electrical 4. Harvest energy from the generator big electrical energy out SOFT CAPACITOR 1. Stretch/Compress mechanical energy converted to elastic potential energy energy for your applications Relax generator Elastic potential energy to electrical energy at a higher energy state Add priming Charge small electrical energy in THE ENERGY HARVESTING CYCLE

16 See StretchSense on YouTube StretchSense Glove Demonstration MIT 7 Finger Robot Heddoko Smart Sports Clothing

17 Contact us at

Active elastomer components based on dielectric elastomers

Gummi Fasern Kunststoffe, 68, No. 6, 2015, pp. 412 415 Active elastomer components based on dielectric elastomers W. Kaal and S. Herold Fraunhofer Institute for Structural Durability and System Reliability