In a recent article published in the journal Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies, researchers introduced a toolkit and workflow inspired by special effects (SFX) makeup methods that allow for reconfigurable and adaptable on-skin prototypes. This approach seeks to enable on-body adjustments and to support iterative design, making prototyping more flexible and user-centered.
Study: SkinLink: On-body Construction and Prototyping of Reconfigurable Epidermal Interfaces. Image Credit: Nejron Photo/Shutterstock.com
Background
Human skin, with its soft, adaptable, and complex surface, offers a unique medium for integrating wearable technologies that allow users to engage in subtle, touch-based interactions within easy reach. Emerging advancements in on-skin technology have driven the development of highly flexible devices through various fabrication techniques, including inkjet and screen printing, water transferring, lamination, and free-hand painting.
Although these approaches enable the creation of customized designs suited to specific body locations, most devices become fixed upon fabrication, limiting adaptability during prototyping. Additionally, current materials often lack the flexibility and stretch needed to accommodate the skin's dynamic and non-uniform surface. By developing SkinLink, a toolkit for flexible on-skin prototyping, this work introduces an adaptable modular circuit design that includes flexible printed circuit boards (FPCBs) and stretchable connectors.
These components are engineered to conform to various body contours and withstand movement, enabling dynamic, reconfigurable on-skin interfaces. A usability study demonstrates SkinLink’s ability to enhance the flexibility and comfort of on-skin devices, offering a user-friendly toolkit for both experienced designers and novice makers.
The Current Study
The study comprised three main stages: a 5-minute introduction, a 60-minute circuit fabrication session, and a 25-minute post-study survey and interview. Initially, participants were introduced to the principles of on-skin prototyping and the specific circuit components.
During the fabrication session, each participant created two circuits with the same functionality, using modules from two distinct toolkits. These circuits were then applied to the participant’s chosen body locations. To minimize bias and gather comprehensive feedback, tasks were organized using a within-subject design, with the order of toolkit usage counterbalanced among participants.
The post-study phase involved a semi-structured interview focused on fabrication experience, wearability, aesthetic flexibility, and potential improvements. Two researchers facilitated the sessions, recording video and audio for later analysis.
The toolkit for each session contained materials necessary for building functional circuits. For the SkinLink setup, components included an Inertial Measurement Unit (IMU) sensor, a 4-LED module, microcontroller units, and four types of trace modules in multiple lengths, along with prosthetic silicone for secure skin adhesion. In contrast, the SkinKit toolkit provided customized PCB modules, flexible trace materials, and double-sided tape for skin application.
Fourteen participants (10 females and 4 males, ages 19-28) were selected based on demographic surveys, with backgrounds in STEM or design fields. Quantitative data included time spent, number of modules used, and skin surface area coverage. A 7-point Likert scale survey gauged ease of fabrication and wearability, analyzed using the Wilcoxon signed-rank test. Qualitative interview data were transcribed and coded iteratively to identify thematic patterns.
Results and Discussion
The study findings include both quantitative data on fabrication time, component use, and skin coverage, and qualitative insights from participant interviews. Results revealed that SkinLink prototypes required fewer wire modules (2.14 average) than SkinKit (5.21 average), indicating a more efficient layout with SkinLink. While both toolkits enabled swift fabrication under 13 minutes, SkinLink’s silicone-based adhesion process required additional solidifying time, though this did not significantly extend overall fabrication time compared to SkinKit.
Participants generally appreciated SkinLink’s form factor, citing its smaller surface area and stretchable, flexible trace modules as beneficial for versatile placements, especially on body areas with dynamic movement like wrists and fingers.
In contrast, SkinKit’s rigid modules and larger footprint limited its suitability to larger, flatter body areas. Participants also noted that SkinLink’s smaller, adaptive traces minimized discomfort, conforming smoothly to skin contours and remaining nearly unnoticeable. However, SkinKit’s larger adhesive coverage was described as less comfortable, especially over extended wear.
On the aesthetic front, SkinLink received positive feedback for its metallic, jewelry-like appearance, contributing to a futuristic look that many participants favored. Suggestions included adding color-coded or width-varied traces for easier customization. Regarding social wearability, several participants indicated openness to using either toolkit in public if practical. Overall, the study confirmed that SkinLink provides a more flexible and adaptable on-skin prototyping option, balancing ease of fabrication with comfort, aesthetics, and versatility.
Conclusion
In conclusion, SkinLink introduces an innovative on-body fabrication method for creating on-skin interfaces, utilizing prosthetic makeup techniques. The customized construction kit enhances the prototyping process with adaptive traces and flexible circuit modules, allowing for seamless integration with the wearer's body.
The approach not only facilitates design flexibility and ease of modification but also supports aesthetic customization without compromising functionality. Usability studies and case studies with makeup artists and wearable interface designers highlight SkinLink's potential to expand creative possibilities in hybrid on-skin designs, fostering greater participation from diverse communities in the fields of UbiComp and HCI.
Journal Reference
Ku P.S., Huang K., et al. (2023). SkinLink: On-body Construction and Prototyping of Reconfigurable Epidermal Interfaces. Proceedings of the ACM on Interactives, Mobile, Wearable and Ubiquitous Technologies,7, 2. DOI: 10.1145/3596241, https://dl.acm.org/doi/10.1145/3596241