Engineering A Biodegradable pH-Sensitive Color-Changing Sponge

Overview

Title: Engineering a Biodegradable pH Sensitive Color- Changing Sponge Many sponges are made with harmful microplastics which lead to bacterial growth. Bacterial growth affects dishes that are being cleaned. There is limited research on biodegradable sponges that change color based on pH. My project explores how to create a biodegradable pH sensitive color-changing sponge to signal possible contamination. I approached my project by making 3 prototypes. Prototype 1 had an alginate base layer for structure. The middle layers were cabbage, turmeric and alginate which were the pH indicators. The top layer consisted of flax fiber added for scrubbing strength. Prototype 2 and 3 had a different procedure. The bottom layers were pre-made cellulose sheets for structure and the middle layers were turmeric and alginate as the pH indicator. The top layers were different, the second prototype incorporated coconut fiber with alginate and the third prototype consisted of coconut fiber and agar. This project showed that prototype 2 held up the most in the durability testing. It was tested by completing 100 swipes with soap and water over a cutting board. The basic and acidic solutions for the pH indicator testing both changed color showing that this project was successful and met the design criteria. The goal was to create a biodegradable pH sensitive color-changing sponge which was successfully designed and changed color based on different pH levels.

Competition history

• CSEF 2026 Environmental Engineering (Track 2) (Junior Division) · Entry J-12-20

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