Design and Simulation of CMOS Based Magnetic Sensor for Biosensing Applications

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Mafi, Alireza | 2022

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 55210 (05)
University: Sharif University of Technolog
Department: Electrical Engineering
Advisor(s): Akbari, Mahmood; Fotowat-Ahmady, Ali
Abstract:
This paper presents a scalable and ultrasensitive magnetic biosensing scheme based on on-chip LC resonance frequency-shifting. The sensor transducer gain is demonstrated as being location-dependent on the sensing surface and proportional to the local polarization magnetic field strength |B|2 generated by the sensing inductor. To improve the gain uniformity, a periodic coil is proposed as a substitution for the standard process coil. As an implementation example, the circuit is designed in a 65nm CMOS process. The spatially uniform sensor gain of the array is verified by COMSOL simulations. Overall, the presented sensor demonstrates an improvement in the uniformity of the inductor’s magnetic field from 224.6% for the standard CMOS inductor to 107.65% for the periodic coil designed in this paper. Furthermore, maximum to minimum frequency shift due to the magnetic bead proximity decreased from 343774 for the standard CMOS inductor to 2.57 for the proposed method of this paper.
Keywords:
DNA Molecule ; Magnetic Sensor ; CMOS Integrated Circuit ; Lab-on-a-Chip ; Cross Coupled Oscillator ; Biosensor

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