Real-Time Biomagnetic Signal Processing for Uncooled Magnetometers in Cardiology

Despite obvious advantages over their electric counterparts, magnetic measurements are still performed very rarely for medical diagnosis. The high operating costs of established systems with a sufficient limit of detection, mainly based on superconducting quantum interference devices, prevent the spread of magnetic diagnostic procedures. Consequently, the demand for alternative low-cost magnetic sensor systems is large. Several suitable, uncooled sensor concepts exist, but their usability-especially, when operated outside magnetically shielded chambers-requires improvement. This paper highlights basic, real-time signal processing concepts, and implementations to improve the signal quality for different biomedical applications with a focus on cardiology in unshielded measurement environments. Several processing steps in the digital domain are described, such as noise reduction (by means of cancellation and suppression), adaptive sensor signal combination, and adaptive signal averaging. Finally, basic cardiologic feature extraction methods are performed using uncooled magnetometers in combination with the described signal enhancement stages.