Hi, I'm Katherine Song. This is a presentation of our paper, "Lotio: Lotion-Mediated
Interaction with an Electronic Skin-Worn Display." Lotions and creams are an important part of daily
self-care practices around the world. The act of applying lotion is accompanied by tacit knowledge
and past experiences. When a user applies a medicinal ointment, they are intrinsically
thinking about their health. When applying makeups, they are primed towards aesthetics.
Semantically linking the stimuli of the act of applying a lotion and the transformation enacted
by a lotion-mediated wearable can enable more meaningful interactions with and more intuitive
interpretations of skin-worn technologies. We propose the concept of Lotion Interfaces, a
class of technology that leverages existing mental models to make this practice more meaningful,
informative, and fun. The on-skin interaction model for Lotion Interfaces is as follows:
The user wears skin-worn technology. This technology may take the form of a wearable
sticker, makeup, or a tattoo, among others. The user applies lotion over the skin-worn
technology. While a diverse range of lotions, creams, and gels can be used, the lotion must
be perceptible to the Lotion Interface, either through electrical or chemical properties.
The skin-worn technology senses the lotion and enacts some transformation. Transformations
may be visual, as shown here, tactile, or digital (for example, setting an alarm,
changing the mode of a connected wearable device). The lotion is absorbed, evaporated, or removed.
The designer may allow the transformation to persist beyond the act of applying lotion itself.
In this talk, we detail the design, fabrication, and applications of Lotio,
an exemplar Lotion Interface that senses lotion and enacts a visual transformation.
It is a low-power electrochromic skin-worn display that leverages a DIY-friendly
straightforward fabrication method and safe materials.
Lotio draws inspiration from a rich body of work in on-skin technologies. Prior work has
explored wearables in the form of silicone overlays, temporary tattoos, and bandages.
Some interfaces have sensing capabilities, and others have built-in displays in the form of LEDs,
thermochromic or environmentally-reactive pigments, and electroluminescent displays.
Lotio is in essence a 2-state electrochromic display. Electrochromic display pixels
conventionally comprise an active electrochromic layer and an electrolyte layer positioned between
two conductive electrodes. Lotio is simply composed of a surgical tape substrate with a
thin layer of ink based on PEDOT:PSS, a polymer that is both electrochromic and conductive.
This ink layer doubles as the electrochromic layer and electrodes, simplifying fabrication
and eliminating the need for indium tin oxide or other electrode materials that are expensive,
non-environmentally friendly, or otherwise not suitable for on-skin technologies.
When a voltage is applied between the two electrodes, the electrochromic layer undergoes
a reversible color-changing redox reaction. The fabrication of Lotio is DIY-friendly
and can be done in a few minutes. FIrst, a surgical tape substrate is sanded smooth.
Next, an electrochromic ink is airbrushed onto its surface.
A laser cutter is then used to pattern the substrate.
And transfer tape is used to transfer the design onto the skin.
Lotio can be simply powered by a small battery or existing wearable electronics.
When lotion is applied, one part of the design turns darker in color. The visual contrast may
be modulated by varying the thickness of the electrochromic layer or the voltage
that is applied between two electrodes. Lotio is very low power and exhibits
quasi-bistability, holding its state change without power for over 15 minutes.
Lotio can also detect touch events, as well as the application of lotion.
We use many kinds of lotions and creams for various purposes. Lotio responds
differently to different types of lotion, such sunscreen, medicated ointment, moisturizer,
and hand sanitizer. This is a property that can be both visually observed and sensed digitally.
Lotio may be connected to a small microcontroller or
existing electronics to act as a dynamic display that is activated by lotion.
It can even be powered by decomposable batteries,
creating a wearable that can be completely composted in backyard soil after use.
We conducted a user study with 9 participants to understand perceptions of lotion-mediated
interaction. Participants envisioned wearing Lotio on the hands, wrists, forearms, face, and neck.
They envisioned using Lotio for health monitoring, aesthetics, and nonverbal communication.
They likened it to an extension of self and were especially drawn to Lotio as it changed, "right
before [their] eyes and on [the] skin" (P1). Lotio may embody a connected data stream. When the
wearer applies lotion, the Lotion Interface may pull data from the stream and update accordingly
in an abstract and aesthetic nature as a form of "vibrant matter." For example, Lotio may be
applied on the forearm and hands in henna-inspired designs as part of an Indian wedding ceremony.
Applying essential oils can cause the Lotion Interface to begin to ebb, with portions
becoming darker and others becoming lighter, representing data connected to the use of the
wedding hashtag online. The dynamic nature of the interface can remind the wearer of the family and
friends who were able to attend the celebration, inspiring feelings of delight and fondness.
Lotio may also be patterned such that a design or message is revealed only when lotion is applied,
providing new opportunities for playful experiences with friends. Imagine that Sally
receives a Lotio patch from Lilly in the mail. The design looks like a decorative abstract circular
tattoo. The next morning when getting ready for work, she excitedly puts it on her arm. Later that
day, Sally is feeling stressed and reaches for her lotion infused with soothing lavender oil.
Nervously rubbing it all over her hands and arms, she notices that her Lotio patch from Lilly has
transformed into a pulsating heart. Smiling, she thinks of Lilly and is overcome by a sense of
happiness and gratefulness for their friendship. Feeling refreshed and re-centered, she returns
to work. These two application examples are just a small subset of potential interactions with Lotio.
Lotio is just one of many possible Lotion Interfaces. A multi-pixel Lotio-inspired
interface may be made by separating 2 layers of PEDOT:PSS strips with a single layer of
insulating surgical tape. When lotion is applied, it is absorbed through the surgical tape layers,
and selective pixels may be activated by addressing particular rows and columns,
similar to a conventional passive matrix display. Beyond Lotion Interfaces that are based on
visual changes, embodiments that utilize other materials that create textural, haptic, or even
olfactory changes could expand the richness of our interactions with lotions. Lotion might rehydrate
integrated hydrogel beads to create shape changes that are both visible to others and perceivable
by the wearer. Lotion might also chemically react to a Lotion Interface to produce heat.
We hope that future designers will be inspired by this work and consider the affordances of lotion
in interaction design. Furthermore, we hope that our approach can be influential beyond the skin,
inspiring designers to examine existing practices to find new embodied interaction modalities.
On behalf of my co-authors - Christine Dierk, Cindy Tung, and Eric Paulos - I
thank you for watching. Please don't hesitate to reach out to us if you have any questions.