Nonsinusoidal in situ electric field caused by magnetic deactivator device for EAS labels-assessment of field strength inside a detailed anatomical hand model

Abstract

In order to evaluate the localised magnetic field (MF) exposure of the cashier's hand due to a particular demagnetization device (deactivator) for single-use labels of an acoustomagnetic (AM) electronic article surveillance (EAS) system, comprehensive measurements of the MF near the surface of the deactivator, and numerical computations of the induced electric field strengthE_i, were performed in high-resolution anatomical hand models of different postures and positions with respect to the deactivator. The measurement results for magnetic inductionBwere assessed with respect to the action levels (AL) for limb exposure, and the computational results forE_iwere evaluated with respect to the exposure limit values (ELV) for health effects according to European Union (EU) directive 2013/35/EU. For the ELV-based assessment, a maximum of the 2 × 2 × 2 mm³averagedE_i(maxE_i,avg) and the respective 99.9th, 99.5th, and 99.0th percentiles were used. As the MF impulse emitted by the deactivator for demagnetization of the AM-EAS labels was highly nonsinusoidal, measurement results were assessed based on the weighted peak method in the time domain (WPM-TD). A newly developed scaling technique was proposed to also apply the WPM-TD to the assessment of the (nonsinusoidal)E_iregarding the ELV. It was used to calculate the resulting WPM-TD-based exposure index (EI) from frequency domain computations. The assessment regarding the AL for limbs yielded peak values of magnetic induction of up to 97 mT (measured with a 3 cm²MF probe on top of the deactivator surface) corresponding to an EI of 443%. However, this was considered an overestimation of the actual exposure in terms ofE_ias the AL were intentionally defined conservatively. A WPM-TD-based assessment ofE_ifinally led to the worst case EI of up to 135%, 93%, 78%, and 72% when using the maxE_i,avg, 99.9th, 99.5th, and 99.0th percentiles, respectively.

Keywords: 2013/35/EU; EAS deactivator; ICNIRP; magnetic field; occupational exposure.