Fazri Firdaus, Rizqi A’mal Hibatullah Tabrani, Galih Aji Prayoga, Zurnansyah, Harlina Ardiyanti, Emi Kurnia Sari, Nurul Imani Istiqomah, Ganesha Antarnusa, Edi Suharyadi
This study investigates a giant magnetoresistance (GMR) chip-based biosensor system using Fe3O4 nanoparticles as magnetic labels, synthesized through conventional co-precipitation (CS) and green synthesis (GS) methods using Moringa oleifera (MO) leaf extract. The AAL024 commercial GMR sensor is integrated with a differential operational amplifier (OA) to amplify its analog signal, which was routed to a 16-bit ADS1115 analog-to-digital converter (ADC) for high-resolution digitization. The Arduino Uno microcontroller read the digitized data via the I2C communication protocol and displayed it as an output signal on a PC. The synthesized Fe3O4 nanoparticles exhibited soft-ferromagnetic properties, with saturation magnetization values of 59.18 emu/g (CS-Fe3O4), 64.68 emu/g (GS-Fe3O4, 1:7), and 30.63 emu/g (GS-Fe3O4, 1:3). These magnetic properties significantly affected their biosensing performance. The GMR sensor enabled rapid detection within 30 s, showing high sensitivity values of 4.16, 4.61, and 3.71 mV/(mg/mL) and a low limit of detection of 1.13, 1.02, and 1.66 mg/mL for CS-Fe3O4, GS-Fe3O4 (1:7), and GS-Fe3O4 (1:3), respectively. Among the tested samples, GS-Fe3O4 with a 1:7 MO ratio yielded the best sensor performance, whereas the 1:3 ratio provided a balance between functionality and environmental sustainability. These findings demonstrate that GMR-based biosensors combined with green-synthesized Fe3O4 nanoparticles are promising platforms for fast, sensitive, and eco-conscious biodetection applications. © 2025 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Department of Physics Education, Universitas Sultan Ageng Tirtayasa, Serang, Indonesia; Department of Physics, Universitas Gadjah Mada, Yogyakarta, Indonesia; Department of Physics, Institut Teknologi Sumatera, Lampung Selatan, Indonesia