A naked-eye detection polyvinyl alcohol/cellulose-based pH sensor for intelligent packaging

Area of Science:

• Materials Science
• Analytical Chemistry

Background:

• Naked-eye detection pH sensors are crucial for food safety.
• Developing robust and visually responsive sensors is an ongoing challenge.

Purpose of the Study:

• To develop a visual pH sensor using acidochromic dye-modified cellulose incorporated into polyvinyl alcohol (PVA).
• To evaluate the sensor's performance, including dye anchoring, material properties, pH response, leaching resistance, and application in food spoilage detection.

Main Methods:

• Cellulose was modified with an acidochromic dye and incorporated into a polyvinyl alcohol matrix.
• The resulting material's dye loading, mechanical properties (tensile strength, elongation at break), and thermal stability were analyzed.
• The sensor's colorimetric response across a range of pH values (7, 10, 12) was observed.
• Leaching resistance was tested under acidic and alkaline conditions.
• The sensor was applied to detect spoilage in shrimp.

Main Results:

• Successful anchoring of the acidochromic dye to cellulose was confirmed (up to 170.4 μmol/g).
• Incorporation of acidochromic regenerated cellulose (ARC) enhanced PVA's tensile strength (44%), elongation at break (43.6%), and decomposition temperature (11°C).
• The sensor exhibited distinct color changes: yellow (pH 7), brick-red (pH 10), and purple (pH 12).
• The sensor demonstrated excellent resistance to leaching in harsh pH conditions.
• A visible color change from yellow to brown was observed in spoiled shrimp.

Conclusions:

• The developed PVA-based pH sensor effectively utilizes acidochromic dye-modified cellulose.
• The sensor shows promising mechanical and thermal stability, along with robust pH-dependent colorimetric response.
• Its ability to detect food spoilage in real-time makes it a valuable tool for non-destructive food safety assessment.