Microdroplet magnetic field sensor utilizing magneto-birefringence effect

Horvat, Martin (author), Hribar Boštjančič, Patricija (author), Lisjak, Darja (author), Mertelj, Alenka (author), Osterman, Natan (author)

Despite advancements in magnetometry, achieving precise, real-time local magnetic field sensing in microscale systems remains a significant challenge. Here, a compact and versatile magnetic field sensor is presented that utilizes magnetically induced birefringence in micrometer-sized droplets of an isotropic suspension of magnetic nanoplatelets. By measuring the light intensity with crossed polarizers, it is demonstrated that the sensor's capability to detect magnetic fields in the millitesla range with high sensitivity. Experimental results, supported by numerical simulations, confirm the sensor's accuracy and robustness. Its practical application is validated by measuring the magnetic field of a bent current-carrying wire at the microscale. Additionally, a method is introduced for determining both the magnitude and direction of an unknown field using a specialized polarization camera. This novel approach offers a promising pathway for precise, real-time magnetic field sensing in microfluidic and lab-on-chip applications, combining high spatial resolution with optical detection advantages.

• Language: English
• Keywords: magnetic sensors, nanoplatelets, field-induced birefringence, microscale magnetic sensor, microfluidics
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 8 str.
• Numbering: Vol. 10, iss. 19, art. e00795
• PID: 20.500.12556/RUL-176726
• UDC: 537
• ISSN on article: 2365-709X
• DOI: 10.1002/admt.202500795
• COBISS.SI-ID: 242136835
• Publication date in RUL: 10.12.2025

Record is a part of a journal

• Title: Advanced materials technologies
• Publisher: Wiley
• ISSN: 2365-709X
• COBISS.SI-ID: 31843367

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: magnetni senzorji, magnetometri, dvolom, mikrofluidna tehnika

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: J2-50089
• Name: Fourierova korelacijska mikroskopija za karakterizacijo delcev in velocimetrijo v kompleksni mehki snovi

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P1-0192
• Name: Svetloba in snov