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[Display omitted] • The introduced folding magnetization allows for higher magnetic flux density. • The ink direct written helped to test variable structure quickly. • The structure designed was found that the signal changed linearly with the load. • We demonstrated an isolated application scenario, sealed and wireless. The development of flexible tactile sensors is an emerging field due to their wide applications ranging from human-robot interactions to wearable electronics. This paper proposes a flexible tactile sensor based on the magnetic field for detecting both forces and positions, which exhibited a linear relationship. The direct ink writing technology was used to fabricate magnetic elastomers for the quick test of variable patterns. The introduced folding magnetization allows for a higher magnetic flux density in the designated position which made it possible to get rid of magnets. A pattern was designed and printed. The linear relationship was found to be linear (R2 > 0.98) between the magnetic field signal and the magnitude and position of the load force. Moreover, the untethered sensor was proven to work well in the sealed box, which is expected to serve as the electrical skin of robots or the tactile sensor in extreme environments. [ABSTRACT FROM AUTHOR]

• An axial MagLev device with unified mathematical model is proposed. • The measurement sensitivity is increased by ∼20x through enlarging magnets' separation distance. • The density of living cells is first measured by the axial MagLev device. • A non-destructive defects detection method via axial MagLev is demonstrated. • Ultrasonic measurement technique is combined with axial MagLev. Magnetic levitation (MagLev) is an emerging technology that levitates materials in paramagnetic media, yet standard MagLev devices that are based on two identical square magnets grants limited operational space and applicability. This study focuses on the axial MagLev configuration, which are based on two identical ring magnets. The approach offers larger operational space as well as greater maneuverability. A unified mathematical model was developed to calculate the distribution of the magnetic field in the axial MagLev configuration, and to correlate the levitated samples' densities and equilibrium positions along the centerline without knowing the samples' weight or volumes. With the mathematical model, the sensitivity of the measurement is predictable and adjustable without the restriction of the linear magnetic field along the centerline. The sensitivity of the axial MagLev device can be increased by ∼ 20 x, i.e., from 66 to 1450 mm/(g/cm3), when the separation distance of magnets is increased from 8 to 32 mm. To demonstrate the potential for the wide applicability, density measurement of living cells, defect detection of polymeric products, as well as a combination of axial MagLev and ultrasonic measurement approach are carried out. The proposed method has prospects for broad applications in areas such as biomedicine, material science, and measurement engineering. [ABSTRACT FROM AUTHOR]