Detecting Magnetic Ink Barcodes with Handheld Magnetoresistive Sensors

TL;DR

This paper presents a novel handheld magnetic barcode reader using tunnel magnetoresistive sensors, capable of reading magnetic ink barcodes at depths of 1mm and resolving structures as thin as 200μm, enhancing non-contact data retrieval.

Contribution

The study introduces a TMR sensor-based device for magnetic barcode reading, overcoming contact limitations of traditional inductive heads and enabling deeper, non-contact data access.

Findings

Reads magnetic barcodes at depths of at least 1 mm.

Resolves structures as thin as 200 μm in contact.

Uses conventional LaserJet toner for printing magnetic codes.

Abstract

Information encoding in barcodes using magnetic-based technology is a unique strategy to read data buried underneath non-transparent surfaces since a direct line-of-sight between the code and the reader is not required. This technology is of particular interest in secure labelling and recyclable packaging applications. However, current magnetic reading heads, such as those employed for magnetic ink character recognition, need to be placed in contact with the magnetic structures, limiting the depths at which the information can be read. This paper describes a strategy to overcome that limitation by replacing the traditional inductive heads with tunnel magnetoresistive (TMR) sensors. Soft-magnetic codes can be printed using conventional LaserJet toners and, by having their magnetisation set with a permanent magnet included in the device, the resulting magnetic field can be read using a TMR sensor. We demonstrate that such a device can read barcodes at depths of at least 1 mm. It can also resolve individual structures as thin as 200 {\mu}m when used in contact.