A new　nanoparticles-based　sensing　platform　was　designed　for　high-through　electrochemical　immunoassay　of　ferritin　(FET)　biomarker　on　a　magneto-controlled　microfluidic　device　by　using　anti-FET　capture　antibody-conjugated　magnetic　sensing　probes.　Thionine-doped　calcium　carbonate　(CaCO3)　nanoparticles　labeled　with　anti-FET　detection　antibodies　were　utilized　as　the　recognition　elements.　Introduction　of　target　FET　caused　the　sandwich-type　immunoreaction　between　two　antibodies.　The　formed　immunocomplexes　were　attached　onto　magnetic　microfluidic　sensing　interface　through　an　external　magnet.　Subsequently,　the　carried　CaCO3　nanoparticles　were　dissolved　under　acidic　conditions　to　release　the　doped　thionine　molecules　with　redox　activity.　The　thionine-based　voltammetric　signals　increased　with　the　increment　of　target　FET　levels　within　the　linear　range　0.01–100　ng　mL−1.　The　limit　of　detection　was　7.9　pg　mL−1　FET.　Good　analytical　properties　such　as　selectivity,　reproducibility,　and　accuracy　were　achieved　with　the nanoparticles-based　magnetic　electrochemical　immunoassay.　More　significantly,　the magnetic　microfluidic　electrochemical　immunoassay　provides　new　opportunities　for　rapid,　simple,　and cost-effective　serum　sample analysis.　©　The　Author(s),　under　exclusive　licence　to　Springer-Verlag　GmbH　Austria,　part　of　Springer　Nature　2025.