Electrochemical sensing platforms including nanostructured materials have attracted increasing attention for diagnostic applications in recent decades. People in resource-limited places, particularly in low- and middle-income countries, continue to face problems finding high-quality medical treatment and technologies. This thesis aims to create affordable electrochemical-based point of care (PoC) diagnostic systems using laser-scribed graphene (LSG) material as the sensing platform. The use of LSG sensors for diagnostic purposes has been gaining attention. Compared to established methods for graphene synthesis, laser scribing provides many advantages, such as cost-effectiveness, fast electron mobility, mask-free production, green synthesis, good electrical conductivity, porosity, mechanical stability, and large surface area. Surface enhancement techniques hold great importance for sensitive and selective electrochemical performance. The first part of this dissertation includes the LSG fabrication and the possible nanoparticle deposition effect on LSG surfaces, particularly gold and silver nanoparticles. The electrodeposition technique was chosen to enhance the electrocatalytic activity with high surface coverage, higher sensitivity, and ease of surface modification. We also focused on possible surface activation techniques on LSG electrodes to achieve an enhancement in surface area through electrochemical strategies. In the second part of this dissertation, we focus on surface functionalization methods for the development of self-diagnostic devices. Namely, the LSG surface was engineered by recognition units such as antibodies, enzymes, and aptamers, as well as molecular imprinting as a non-biological approach. As a readout system, a custom-made potentiostat called KAUSTat was developed. The suggested devices have the potential to replace costly health care instrumentation with simple and practical miniaturized smart systems when combined with smartphone applications via Bluetooth connection.