This repository contains the study code for the paper "pHigment: Designing Biodegradable Single-Use Cosmetics for On-body Chemical Sensing."
Consider replacing existing single-use makeup products with biodegradable, colorimetric biosensing materials. Red Cabbage powder is a colorimetric dye that reacts to pH giving insights into dental, vaginal, and skin health.
pHigment explores the integration of biosensing and biodegradable materials within single-use cosmetics, including temporary tattoos, eyeliner stickers, and press-on nails. These formats often come into contact with body fluids such as sweat, tears, or saliva, and allow for diverse placement on the body, customizable shapes, and a range of colors—features that support the visual transitions of colorimetric biosensors. Unlike conventional cosmetics that absorb into the skin or wear off, these products retain their material structure and are typically discarded after brief use, contributing to landfill waste due to their synthetic components. By focusing on single-use cosmetics, this project addresses both the functional potential of on-body sensing and the environmental impact of cosmetic disposability.
We frame this project around the dual objective of designing on-body colorimetric biosensors that promote health and environmental awareness, while using biodegradable materials suited for single-use lifecycles. We present four main contributions:
(1) The articulation of this duality in biocosmetic interface design. We create a set of working prototypes—eyeliner, temporary tattoos, and press-on nails—that demonstrate how ephemeral cosmetic products can serve as both responsive sensors and compostable, body-worn devices;
(2) A DIY, skin-safe, biodegradable fabrication process based on alginate formulations with embedded anthocyanin;
(3) A detection system combining a custom case for light control and a computer vision app that converts RGB color to pH value;
(4) A compostability test of the material under natural conditions.
- Olivia Bates - University of California, Davis, USA
- Alyssa Yee - University of California, Davis, USA
- Phillip Gough - Design lab, School of Architecture, Design and Planning, The University of Sydney, Sydney, NSW, Australia
- Anusha Wishana - School of Computer Science, The University of Sydney, Sydney, NSW, Australia
- Katia Vega - University of California, Davis, USA
This project explores the dual design challenge of creating on-body interfaces that are both environmentally sustainable and capable of on-body chemical sensing. We present a set of single-use cosmetic prototypes—eyeliner, temporary tattoos, and press-on nails—that respond to chemical changes in body and external fluids while being fully compostable after use. Each prototype is fabricated using alginate as a biodegradable substrate and anthocyanin, derived from red cabbage powder, as a colorimetric indicator. We describe the fabrication process and introduce a system that includes a custom- designed case and a computer vision–based mobile application that interprets color changes and outputs corresponding pH values. We report technical evaluations of the materials, system functionality, and compostability. This work contributes to biocosmetic interface design by demonstrating how ephemeral body-worn form factors can simultaneously serve as both responsive chemical sensors and components of a circular materials strategy.
- Eyeliner, Temporary Tattoos, and Press-On Nails: Designed to indicate pH levels through color changes.
- Mobile App: Utilizes a CNN model for pH level detection.
- Data Collection: Includes variations in lighting, camera conditions, and user responses.
- Improved Detection: Shows enhanced pH variation detection over traditional methods.
Ingredients: (Measure in Mixing Order)
- 100 g Water
- 0.5 g Red Cabbage Powder
- 0.1 g Titanium Dioxide
- 5 g Glycerine
- 2.5 gSunflower Oil
- 3 g Sodium Alginate
Instructions:
- Use an immersion blender
- Add sodium alginate slowly (this prevents clumping)
- Use a vaccumm chamber to remove trapped airbubbles
- Pour on Acrylic Sheet
- Use acrylic strip or scraper to spread evenly
- Spray Calcium Chloride solution to cure
- Leave to dry for 6 days
- Following Cricut Tattoo Paper instructions, stick the colorimetric sheet on instead
- Cut using Silouhette Cameo
- Stick sticker on nails, eyes, or anywhere on your arms or legs to read the pH of your environment
- Mobile Application: Located in the
appfolder.
We welcome contributions to enhance the project. Please fork the repository and submit pull requests with your improvements. For major changes, please open an issue to discuss your proposal before making changes.
This material is based upon work supported by the National Science Foundation under Grant No 2146461, and UC Davis Academic Senate.
This project is licensed under the MIT License - see the LICENSE file for details.
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