1. Rachel Miller, Timothy F. O’Connor III, Armando Urbina, Darren J. Lipomi*
Department of NanoEngineering, UC San Diego nanoengineering.ucsd.edu
darrenlipomi.com
Abstract Data Processing
Existing glove-like sensors for decoding human hand gestures
—e.g., American Sign Language (ASL)—have been
demonstrated before, but they have employed bulky
electronics and had limited sensitivity at small strains. We
have fabricated and employed piezoresistive strain sensors
comprised of graphene decorated with thermally evaporated
palladium nanoislands. These composite thin films are
integrated into a sensor system that wirelessly measures the
wide range strain corresponding the motion and configuration
of the hands and fingers. These sensors have demonstrated a
large gauge factor, stable baseline, and ability to detect strain
as small 0.1% with a dynamic range of over four orders of
magnitude in strain (0.001% – 10% strain). Data from nine
sensors on the knuckles were transmitted wirelessly by
Bluetooth to a computer, then interpreted by purpose-written
software to decode the signal. Moreover, this demonstration
uses imperceptible sensors that can be placed on commonly
available textiles. While we demonstrate an application in
ASL, the piezoresistive sensor system is also amenable to
instrumented gloves for surgical training, prostheses and
electronic skin and silent wireless communication for covert
operations.
Fabrication
Fabrication Process:
Palladium Nanoisland decorated graphene on
copper and PET; copper selectively etched in
ammonium persulfate to create contacts
Output Signals
Support & References
Pic
Device Assembly and TestingHuman Signal to Digital Signal
[1] Savagatrup, Printz, O’Connor, Zaretski, Lipomi.
Chem. Mater. 2014, 26, 3028−3041
[2] Mut, Michelle. "Robotic Surgery and Minimally
Invasive Surgery." Prezi.com. Worcester Polytechnic
Institute, 14 Apr. 2014. Web. 06 Oct. 2016.
Sensor cross-section (not to scale)
Wireless Transmission and Decoding of Hand Gestures Using
Graphene Palladium Nanoisland Sensors
Future Work
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Integrate stretchable materials [1]
• Better suited for range of finger motion
• Increase durability
• Robust to mechanical strain
Increase sensor density
• Interpret all 26 letter in ASL alphabet
Adapt to virtual reality tasks
• Education
• Telesurgery
• Entertainment
Change in voltage in response to change in strain
• Distinct changes voltage usable for on/off in majority
sensors.
• Steady baseline within each sensor.
• Although baseline resistances (or voltages) may differ from
sensor to sensor, this disparity is easily compensated for in
the code and does not negatively affect ability to interpret
the data.
Above: Remote surgery using traditional controls [2]
(Top Left and Far Right) Functional prototype:
• Sensors mounted on glove
• Majority of sensors were functional
• Able to transmit information to computer wirelessly
(Bottom Left) Sensors Pre and Post Flexing cycles:
• No signs of mechanical failure after 20 cycle.
• Note: Sensor did not elongate after cycles
Sensor system
mechanisms:
Sensor circuit is a voltage
divider. As sensors
experience strain, output
voltage changes and is the
change is detected by the
Arduino.
Logic:
Although each sensor is
analogue, code has
threshold values to
determine on/off signals.
Every letter is assigned to a
combination of on/off
signals.