Modeling and Development of a Magnetic Shielding Mechanism

Background: Medical devices relying on biosignal acquisition are susceptible to electromagnetic interference. Current approaches are ineffective at shielding low amplitude, low frequency biosignal measurements. Objective: To develop a magnetic shielding mechanism to improve shielding effectiveness (SE) for low amplitude application. Method: A three layer shielding mechanism with the two inner layers made of cold rolled (CR) steel and an outer layer of aluminum (Al) was investigated. Modeling and simulations were performed using finite element analysis. Experiments were performed on shielding samples of CR steel and Al. Results: (1) The average SE for the three layer system was found to be S6.02 and 47.38 decibel by simulation and experiment respectively. (2) By incorporating a conductive layer of Al, performance was investigated up to 25 KHz. SE was observed to increase with the increase in interfering signal frequency. Conclusion: The proposed shielding mechanism would reduce the interference level of low amplitude, low frequency biosignal measurements