Experimental E-Ink Tattoo Interface Prototype

Athletes and fitness enthusiasts who are serious about improving often have complex workout routines and need to keep track of their progress. This means memorizing everything or carrying around a notebook and pencil, cellphone, tablet, or other device. Pair this with a handheld stopwatch or wrist watch and an iPod with headphones and you’re left with distractions that impair the quality of a workout.

View Project Deck
Split Timer Prototype Demo
Open Interface Demo
Music Interaction Demo


My sketches helped visualize where on the arm the tattoo would be best located for easy interaction and visibility. I also explored some gestured-based controls for hands-free interaction.

Project Deck


  • 1sp (skin pixel) = 0.25mm = 0.94px = 0.71pt
  • Smallest average forearm size: 220 x 70mm = 880 x 280sp
  • Thinnest tattoo needle: #6 needle at 0.20mm = 0.8sp
  • Minimum line weight: 0.25mm = 1sp
  • Minimum type size: 3.53mm = 10pt = 14sp
  • Touch target size: 7-10mm = 28-40sp
  • Information zones: Least important to most important
  • Responsive mode: Horizontal to vertical, inside to outside
  • Alternate display: Outside wrist, hand
  • Alternate interactions: Gesture based
  • Skin color: All supported

Technology Research

  • Atmel® ATBTLC1000-MR110CA Bluetooth Low Energy module
  • $11 per unit (low volume)
  • 2 × 2mm
  • 1.8 – 4.3V
  • Quallion QL0003I Li-ion cell
  • 2.9 x 11.8mm
  • 3mAh at 3.6V
  • Implantable
  • Extended cycle life
  • E-ink two-pigment subdermal display

Wireframes & UI Planning

Various states and interaction sketches of the proposed app.