Automated Papanicolaou staining system (PapDisc) based on centrifugal microfluidics using cut-off valves

Abstract

Cervical cancer, primarily caused by the human papillomavirus (HPV), remains a significant global health issue, especially in underserved regions. Despite the availability of screening methods, barriers such as limited access and resource constraints contribute to late-stage diagnoses and high mortality rates. This study introduces a novel platform utilizing centrifugal microfluidics to automate the labor-intensive Pap smear staining process, providing a cost-effective and accessible solution. The system features a disc-shaped cartridge preloaded with staining dyes and fixation liquids, following the Papanicolaou (Pap) smear staining protocol. The sample preparation is executed by applying a specific rotational speed profile via a rotor. A novel valving mechanism (Cut-off valve), driven by centrifugal and magnetic forces, acts as the primary fluidic unit to control the precise and sequential staining protocol. The functionality of these valves is demonstrated through numerical simulations for obtaining the rotational speed, using the intensity of the magnetic flux density $\bar{B}$ around several different dimension magnets along with experimental validations. This platform presents a practical and scalable approach to cervical cancer screening, with the potential to enhance diagnostic accuracy and accessibility, particularly in low-resource settings.