Paper-based sensors offer a promising platform for a wide range of applications including health diagnostics, environmental monitoring, and food quality control. Compared to plastic and glass substrates, paper is inexpensive, disposable, abundant, and easy to transport. The low cost and ease of use make paper-based sensors attractive for developing world applications where simplicity and affordability are crucial. In the field of environmental monitoring, real-time detection of heavy metals and other pollutants is critical as sample conditions can change throughout the day and during the transportation back to the lab. Thus, there is a need for sensors that can enable on-site detection and accurate monitoring of environmental conditions. Researchers have focused on developing paper-based sensors with simple fabrication techniques and operation, making them suitable for developing world applications where simple and easy-to-use devices are highly desirable. With further research and development, paper-based sensors have the potential to play a significant role in monitoring and improving the quality of our environment, food, and health. Although paper-based sensors have emerged as a promising platform for various applications including health diagnostics, environmental monitoring, and food quality control due to their low cost, disposability, abundance, and easy transport, however, researchers face several challenges in developing paper-based sensors. One significant challenge is the difficulty in multiplex analysis. As the shape and design of the sensors become more complex, there is a potential for cross-talk among the different channels. The future of multiplex analysis may see the development of more intricate 3-D paper architectures that can detect multiple analytes using a combination of techniques. Another challenge is the need for low power and portable analysis techniques.