Paper-Based Magneto-Resistive Sensor: Modeling, Fabrication, Characterization, and Application

In this work, we developed and fabricated a paper-based anisotropic magneto-resistive sensor using a sputtered permalloy (Ni [Formula: see text] Fe [Formula: see text]) thin film. To interpret the characteristics of the sensor, we proposed a computational model to capture the influence of the stochastic fiber network of the paper surface and to explain the physics behind the empirically observed difference in paper-based anisotropic magneto-resistance (AMR). Using the model, we verified two main empirical observations: (1) The stochastic fiber network of the paper substrate induces a shift of [Formula: see text] in the AMR response of the paper-based Ni [Formula: see text] Fe [Formula: see text] thin film compared to a Ni [Formula: see text] Fe [Formula: see text] film on a smooth surface as long as the fibrous topography has not become buried. (2) The ratio of magnitudes of AMR peaks at different anisotropy angles and the inverted AMR peak at the [Formula: see text]-anisotropy angle are explained through the superposition of the responses of Ni [Formula: see text] Fe [Formula: see text] inheriting the fibrous topography and smoother Ni [Formula: see text] Fe [Formula: see text] on buried fibrous topographies. As for the sensitivity and reproducibility of the sensor signal, we obtained a maximum AMR peak of [Formula: see text] , min-max sensitivity range of [Formula: see text] , average asymmetry of peak location of [Formula: see text] [Formula: see text] within two consecutive magnetic loading cycles, and a deviation of 250–850 [Formula: see text] of peak location across several anisotropy angles at a base resistance of ∼100 [Formula: see text]. Last, we demonstrated the usability of the sensor in two educational application examples: a textbook clicker and interactive braille flashcards.