Ever-evolving advances in flexible magnetic sensors are promising to fuel technological developments in the fields of touchless human–machine interaction, implantable medical diagnosis, and magnetoreception for artificial intelligence. However, the realization of highly flexible and extremely sensitive magnetic sensors remains a challenge. Here, we report a cost-effective, flexible, and ultra-sensitive heterostructural magnetoelectric (ME) sensor consisting of piezoelectric Pb(Zr0.52Ti0.48)O3 (PZT) thick films and Metglas foils. The flexible sensor exhibits a strong ME coefficient of 19.3 V cm−1 Oe−1 at low frequencies and 280.5 V cm−1 Oe−1 at resonance due to the exceptionally high piezoelectric coefficient d33 ∼ 72 pC N−1 of the constituent PZT thick films. The flexible ME sensor possesses not only ultrahigh sensitivities of 200 nT at low frequencies and 200 pT at resonance but also shows an excellent mechanical endurance. Through 5000 bending cycles (radii of ∼1 cm), the sensors showed no fatigue-induced performance degradation. This ultrasensitive flexible sensor provides a platform capable of sensing and responding to external magnetic fields and will find applications in soft robotics, wearable healthcare monitoring, and consumer electronics.

The magnetoelectric (ME) heterostructure is composed of ferromagnetic and ferroelectric materials. The heterostructural ME effect originates from piezoelectric effect in the ferroelectric component and magnetostrictive effect in the ferromagnetic component. The magnetoelectric heterostructure has higher magnetoelectric coupling coefficient and lower dielectric loss than the particulate composites, and thus leading to several promising applications such as in the magnetic field sensors, the energy harvesters, antenna and memory devices. In this paper, we review the recent research progress in ME heterostructure for device applications, and present a development course of ME heterostructure. Finally, we also summarize the challenges of developing the ME heterostructure and point out its perspectives.