Microneedle Technologies for Cancer Diagnostics: From Fabrication to Biosensing.

Early precise cancer detection is vital for improving patient outcomes, yet current diagnostic methods often fall short, particularly in enabling continuous and minimally invasive monitoring. Conventional techniques, including tissue biopsy and medical imaging techniques, are hindered by high costs, and limited real-time capabilities. In contrast, microneedle-based biosensors offer a wearable and non-invasive alternative, accessing body fluid to detect cancer biomarkers effectively. These microneedles can monitor physiological parameters and rare chemical analytes, paving the way for advanced point-of-care diagnostics and early intervention. This review examines the materials and fabrication strategies employed in microneedle development, such as polymers, metals, and various manufacturing methods like micromolding, photolithography, and 3D printing. This work also explores key signal readout techniques, focusing on optical and electrochemical approaches optimized for cancer biomarker detection. By enabling multiplexed analysis and continuous monitoring, microneedles present a versatile and precise diagnostic platform. Finally, this work discusses current limitations and propose directions for future research to enhance their clinical impact, underscoring the transformative potential of microneedle technology in cancer diagnostics as an example of the potential for microneedles in early diagnostics.