The ΔE effect magnetic field sensor exploits the frequency shift of a resonator, oscillating at high frequencies, due to the change in Young’s modulus of a magnetostrictive material in a magnetic field. The sensor allows broadband magnetic field measurements at low frequencies down to the DC range, is robust against microphony effects and mechanical noise, and provides full device integrability. Since our first publication of the sensor concept, in 2011 [B. Gojdka et al., Appl. Phys. Lett. 99, 223502 (2011); Nature 480, 155 (2011)] various improvements and modifications of the original set-up have led to an increase in i limit of detection by almost five orders of magnitude down to 35 pTHz-1/2 at 20 Hz. Our current sensor versions are fully integrated microelectromechanical devices and incorporate a piezoelectric AlN layer on top of a poly-Si cantilever and a magnetostrictive FeCoBSi bottom layer. The AlN layer serves two functions: It drives the resonator, and it is used for electrical read out.