Data Storage and Interaction using Magnetized Fabric Justin Chan - PowerPoint PPT Presentation

Data Storage and Interaction using Magnetized Fabric Justin Chan Shyam Gollakota 1

Existing approaches PROJECT JACQUARD LILYPAD ARDUINO Requires batteries 2

Can we create a smart fabric design without any onboard electronics or batteries? 3

Smart fabrics without electronics BATTERY-FREE WATERPROOF 4

Clothes with memory CODES IMAGES 5

Interact with a smartphone in your pocket 6

What are conductive threads used for? 7

Key Observation Leverage magnetic properties of conductive thread 8

Smartphones have magnetometers 9

Our Contributions • First to harness the magnetic properties of conductive fabric for interaction • Provide a detailed characterization of magnetized fabric • Build electronic-free data storage and gesture recognition applications on fabric 10

Characterization of magnetized fabric 11

What do we care about? • Embroidery style • Decay over distance • Decay over time 12

How does embroidery style a fg ect fj eld strength? 2.5cm 100 100 Noise Magnetic field strength (µT) 80 fi eld strength ( � T) Floor 80 Magnetic 60 60 40 40 20 20 0 0 0 1 2 3 4 5 6 7 8 Denser styles have higher fj eld strength 13

How does fj eld strength decay over distance? 2.5cm 2 2.0cm 2 1.5cm 2 60 60 Magnetic field fi eld strength ( � T) strength (µT) 50 50 Magnetic 40 40 30 30 20 20 10 10 0 0 0 5 10 15 20 0 5 10 15 20 Distance from magnetometer (mm) Distance from phone (mm) Works up to distances of 1 cm 14

How does fj eld strength decay over time? Remagnetized 2.5cm 2 2.0cm 2 1.5cm 2 2.5cm 2 2.0cm 2 1.5cm 2 60 60 Magnetic field strength (µT) 50 fi eld strength ( � T) 50 40 40 Magnetic 30 30 20 20 10 10 0 0 0 1 2 3 4 5 6 0 1 2 3 4 5 6 Days Days 28-36% decrease over a week 15

DATA STORAGE EMBEDDING INVISIBLE IMAGES GESTURE RECOGNITION 16

How do we tag clothing? Unreadable on > $500-$2000 smartphones 17

Reading and writing codes Magnetometer 5mm Guard band 1cm 2cm < $0.17 18

Reading the tag on a smartphone 19

How durable are our tags? Change in fj eld strength Hand wash 11% Machine wash 5% Drying 9% Ironing (160°C) 1% 20

Are our tags reprogrammable? 45 40 40 35 fi eld strength ( � T) 30 Magnetic field 30 strength (µT) Magnetic 25 20 20 15 10 10 No degradation in fj eld strength 5 0 0 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 Tag ID Number Number of new magnetic codes 21 21

Fashion accessories with memory 22

EMBEDDING INVISIBLE IMAGES 23

Drawing and reading images ENCODING DECODING 24

How small can each pixel be? 9cm 1.8cm 60 Magnetic fj eld strength (µT) 40 20 0 -20 -40 -60 Smallest pixel size: 1.8 cm 2 25

Expressivity of images 9cm 9cm 2 25 ≈ 33 million possible images 26

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GESTURE RECOGNITION 28

Smartphones Low-power Magnetometer in pockets IoT devices Power: 72µW Cost: $0.80 29

Recognizing gestures 30

X Y Z UP X Y Z DOWN X Y Z LEFT X Y Z RIGHT X Y Z CLICK X Y Z BACK CLICK 31

Real time classi fj er 32

Classi fj er accuracy 0.91 0.01 0 0.01 0.04 0.03 0 Up 7 users Actual Gesture Performed 0 0.9 0.02 0.03 0.03 0.01 0 Down 20 repetitions Left 0 0.03 0.87 0.06 0.02 0.01 0 Right 0.04 0 0 0.94 0.02 0.01 0 90.1% 0.01 0.01 0 0.01 0.92 0.02 0.02 Click accuracy Back 0 0.06 0 0.02 0.04 0.86 0.03 Click Up Down Left Right Click Back Not Click seen Gesture Classi fi ed 33

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How do we improve this? Custom designed textiles + 
 a precise magnetic reader and writer • Generate stronger fj elds • Increase bit density • Longer bit lifespan 35

Conclusions • Harness the magnetic properties of conductive fabric for interaction • Provide a detailed characterization of magnetized fabric • Build electronic-free data storage and gesture recognition applications on fabric 36