Carbon Quantum Dot Fluorescent Stickers for Biochip Authentication

Microfluidic biochips are widely used in biomedical research, clinical diagnostics, and point-of-care testing. However, their complex supply chains make them vulnerable to counterfeiting, overbuilding, and intellectual property (IP) piracy. We present fluorescent carbon quantum dot (CQD) stickers<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> that can be integrated with the polydimethylsiloxane (PDMS) based biochips for authentication. The stickers can be plasma-bonded to biochips made of glass and silicon. A protective spin-coated PDMS layer makes them obscured and tamperproof. However, they are detectable under UV light and can be authenticated via spectral analysis. The scheme exhibits unique excitation-dependent responses associated with the variability of the CQD sizes. This makes it ideal for physical authentication. Reliability studies concerning mechanical, photonic, and thermal degradation have demonstrated highly stable results. The stability of CQDs within the PDMS, their robust excitation-based emission fluorescence response, and the use of waste polypropylene masks make this a sustainable and robust authenticator for biochips.