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A Handheld Printer for Physical Sketching of Circuits and Sensors on Everyday Surfaces

We present Print-A-Sketch, an open-source handheld printer prototype for sketching circuits and sensors. Print-A-Sketch combines desirable properties from free-hand sketching and functional electronic printing. Manual human control of large strokes is augmented with computer control of fine detail. Shared control of Print-A-Sketch supports sketching interactive interfaces on everyday objects – including many objects with materials or sizes which otherwise are difficult to print on. We present an overview of challenges involved in such a system and show how these can be addressed using context-aware, dynamic printing. Continuous sensing ensures quality prints by adjusting the inking rate to hand movement and material properties. Continuous sensing also enables the print to adapt to previously printed traces to support incremental and iterative sketching. Results show good conductivity on many materials and high spatial precision, supporting on-the-fly creation of functional interfaces.

Hardware
- 1x Xaar 128/80 W printhead
- 1x FFC to DIP adapter

Power Circuit:

- 1x 3.7V Li-Ion rechargable battery
- 1x DC-DC Switching Boost Converter (>35V)
- 2x 1K resistor
- 2x 200 resistor
- 2x 1uF capacitor 50V
- 1x 220uF capacitor 50V
- 2x 1N4004 diode
- 2x 1N4740 diode
- 2x IRF9540 transistor
- 2x BC547 transistor

Positioning:

- 1x Optical Flow Sensor PMW3360

Interaction with the device:

- 1x Monochrome 0.96” 128x64 OLED Graphic Display
- 2x Push Button”

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