Paper substrates have been widely used as chemical sensor platforms owing to their eco-friendliness and high processability. Conventional paper-based analytical devices allow single analyte detection, whereas real samples contain multiple analytes at wide concentration ranges. Although multi-sensing devices are required in real-world scenarios, the realization is still challenging. Motivated by this, the author has developed paper-based sensor array devices for multi-sensing. In this regard, cross-reactive optical sensors are appropriate elements to achieve both qualitative and quantitative detection based on pattern recognition. Such cross-reactive chemical sensors on an array show various optical responses on a paper substrate upon the addition of different analytes. The optical sensor elements can be uniformly printed on the paper substrate using office apparatuses. In addition, optical responses of the paper substrate embedded with cross-reactive sensors are rapidly detected using digital recorders, followed by data processing using imaging analysis and pattern recognition techniques. Therefore, paper-based sensor array devices allow not only the simultaneous detection of multiple chemical information but also accurate analysis comparable to stational analytical methods. Herein, the author shows appropriate designs of paper-based sensor array devices and their applicability for real-sample analysis. © 2025 SPIE.