Crafting Material Interfaces

Daekwon Park & Nicole Tariverdian

SmartSkinPresentation_2 (link to our presentation PDF)

STARTER PAPER

SmartSkin: An Infrastructure for Freehand Manipulation on Interactive Surfaces
- Jun Rekimoto

SmartSkin:
A sensor that recognizes multiple hand positions and shapes and calculates the distance between the hand and the surface by using capacitive sensing and a mesh-shaped antenna.

• Layers of mesh transmitter/receiver electrodes (such as copper wires) on the surface.
  The vertical wires are transmitter electrodes, and the horizontal wires are receiver electrodes.
• Resulting in an interactive surface can be large, thin,or even flexible.

The transmitter:
is excited by a wave signal (typically several hundred kilohertz).

The receiver:
receives this wave signal because each crossing point (transmitter/receiver pairs) is a (very weak) capacitor.

The magnitude of the received signal:
Is proportional to the frequency and voltage of the transmitted signal & to the capacitance between the two electrodes.

Benifits of SmartSkin
Unlike Multi-touch Systems:
• No camera is needed.
• Very accurate.
• Can detect shapes not just finger touches (Participants can use their whole arms).

CAPACITIVE SENSING

Capacitive Sensing

http://www.analog.com/library/analogDialogue/archives/40-10/cap_sensors.html

• A technology based on capacitive coupling.
• Used in a variety of sensors.
detecting and measuring:
proximity, position or displacement, humidity, fluid level, and acceleration.

Source: http://en.wikipedia.org/wiki/Capacitive_sensing

Capacitive sensors detect:
• Anything which is conductive or has a dielectric different than that of air.
• Capacitive sensing applications can replace mechanical buttons with capacitive alternatives.
•Other technologies such as multi-touch & gesture-based touchscreens are also premised on capacitive sensing.

Source: http://www.analog.com/library/analogDialogue/archives/40-10/cap_sensors.html

Sensor Products using Capacitive sensing :

MPR121 Capacitive Touch Keypad
• MPR121 and 12 touch sensitive pads.
• Simple ‘keypad’ with an I2C output.
• Four mounting holes as input system instead of traditional buttons.
http://www.sparkfun.com/products/10250

Capacitive Touch Sensor IC
• The IC with an I2C digital interface.
• Much less circutry then a common Capacitive sensor.
http://www.sparkfun.com/products/7902

DIY 3D Controller:

http://www.instructables.com/id/DIY-3D-Controller/

DIY 3D Interface: Tic Tac Toe from Kyle McDonald on Vimeo.

LINKS:
Modular sensor surface:
http://sensacell2.com/Website/
iPhone touchscreen:
http://electronics.howstuffworks.com/iphone1.htm
Capacitive type sensors:
http://www.sparkfun.com/search/results?term=ca
pacitive&what=products
Freespace 2d Controller:
http://vimeo.com/992552