Fabrication of a Micro/Nano-Structure-Based Sensing Platform Using Two-Photon Polymerisation for Detecting Cadmium Ions

The escalating global issue of heavy metal contamination, largely stemming from industrial activities, particularly those in mining, refineries, petrochemical plants, chemical synthesis, fertilizer, paint, and battery production, has significantly contributed to cadmium pollution in water and soil. The World Health Organization (WHO) has established a strict allowable threshold of 3 parts per billion (ppb) for cadmium in drinking water, underscoring the urgent necessity for a detection method that is both sensitive and specific. While conventional techniques like atomic absorption spectrometry and inductively coupled plasma mass spectrometry are highly precise, they are hindered by their high cost, bulkiness, and time-intensive nature. Modern methods, such as fluorescence, colorimetry, chemical, and electrochemical sensing, offer simpler and real-time solutions for monitoring cadmium levels. In this research, we present an innovative approach involving a polymerized 4D structure that incorporates nonmetal-doped carbon quantum dots (CQDs) to enable fluorescence-based detection of cadmium. Our investigation meticulously delves into the fabrication of this hybrid sensor using two-photon polymerisation, demonstrating its potential for integration into the next generation of compact devices designed for cadmium detection.