Papertronics: Integrating Electronics and Microfluidics on Paper for Sustainable Electroanalysis

The widespread use of non-renewable materials in point-of-care (PoC) electroanalysis, such as disposable test strips with electronic meters, has inadvertently contributed to electronic waste. Paper, traditionally used as a passive substrate, offers a renewable alternative but faces limitations in direct conversion into conductive electronic components, hindering its adoption for on-site analysis. Here, we present the development of papertronics, integrating conductive electronic components and microfluidics on a single sheet of paper for sustainable electroanalysis. Using a flame retardant and laser treatment, we enable a direct conversion of cellulose paper into laser-induced graphite (PLIG). By optimizing laser parameters (e.g., laser power, scan speed and defocus/focus), the physicochemical properties of the PLIG are tailored. Microfluidic channels are patterned with sub-millimetre resolution via hot-pressing hydrophobic parafilm into paper at a relatively low temperature of 60 °C for 15 seconds. This process facilitates a seamless integration of paper-based electronic components with microfluidics. Demonstrative applications in pH sensing showed a sensitivity of -40.3 mV pH-1, and lactate biosensing achieved a sensitivity of 0.92 μA mM-1. This study establishes a foundation for cost-effective, environmentally friendly electroanalytical platforms with broad implications in biomedical diagnostics and environmental monitoring.