EIT week35-3 Printed Electronics and Sensing Movement

Printed Electronics and Sensing Movement

Overview

• Course: 6.810 Engineering Interaction Technologies
• Professor: Michael Wessely, Interactive Matter Lab

Sensing Motion

• Types of Motion: Proximity, rotation, elongation, shear, shape.
• Capacitive Sensing: Measures movement by detecting changes in capacitance between pairs of conductive plates.

Capacitance Formula

• General Formula: \(\begin{equation} C = \epsilon \left(\frac{A}{d}\right) \label{eq:capacitance_motion} \end{equation}\)
  • ( A ) = overlapping area between two electrodes.
  • ( d ) = distance between the electrodes.

Specific Movements and Sensing Mechanisms

Proximity Sensing

• Function: Measures the capacitance between electrode pairs to infer the proximity based on signal strength.
  • No finger contact is required for sensing.
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Folding Sensing

• Capability: Measures angles up to 180°; can be extended to 360° with additional electrodes on the reverse side.

Rotation Sensing

• Method: Similar to folding, but allows measurement in multiple directions.

Shearing Sensing

• Configuration: Involves multiple pairs of conductive plates to measure shear movements.
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  Linear Elongation Sensing

• Design: Utilizes more conductive plate pairs to measure elongation.
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Shape Sensing

• Setup: Uses two layers of conductive plates — a main conductive layer and individual lines, forming multiple individual capacitors.
  • Designed to detect changes in shape.

Sensors Enabled by Capacitive Sensing

• Applications: Buttons, sliders, dials, multi-touch pads, and pressure sensors.
• Other Motions: Includes proximity, folding, rotation, linear elongation, shear, and shape sensing.

Example Technologies

• FoldIO: Implements various sensing functionalities using capacitive techniques.
• ShapeMe: Specializes in shape sensing with structured conductive plates.
• Pressure Sensor: Features two conductive plates with a compressible material (neoprene rubber) in between to sense pressure.