A method for controlling the vibration of an element of a nebulizer (100-a, 100-c, 151, 178, 260) having a sealed negatively biased liquid drug reservoir (120, 186) by an electrical signal delivered by a driver (152, 172, 210), the method comprising: driving, by the driver (152, 172, 210), the element of the nebulizer (100-a, 100-c, 151, 178, 260) using the electrical signal, which causes the element of the nebulizer (100-a, 100-c, 151, 178, 260) to vibrate and atomize liquid stored in the negatively biased liquid reservoir (120, 186), the electrical signal comprising a current and a voltage; characterized by measuring, by a phase shift detector of the driver (152, 172, 210), a phase shift between the voltage and the current of the electrical signal driving the nebulizer (100-a, 100-c, 151, 178, 260); based at least in part on the phase shift of the electrical signal driving the element of the nebulizer (100-a, 100-c, 151, 178, 260) measured by the phase shift detector, determining, by a resonant frequency tracker of the driver (152, 172, 210), a resonant frequency of the element of the nebulizer (100-a, 100-c, 151, 178, 260) adjusting, by the driver (152, 172, 210), the frequency of the electrical signal to the nebulizer (100-a, 100-c, 151, 178, 260), wherein a near constant phase shift is maintained between the voltage and current of the electrical signal and the resonant frequency of the element of the nebulizer changes as liquid is atomized and the negative bias pressure within the sealed drug reservoir (120, 186) changes; and based at least in part on the resonant frequency of the nebulizer (100-a, 100-c, 151, 178, 260) determined by the resonant frequency tracker of the driver (152, 172, 210), determining, using a voltage profile of the driver (152, 172, 210), a voltage magnitude for the electrical signal at a particular resonant frequency to maintain consistent droplet size and dosing of the atomized liquid. driving, by the driver (152, 172, 210), the element of the nebulizer (100-a, 100-c, 151, 178, 260) using the electrical signal, which causes the element of the nebulizer (100-a, 100-c, 151, 178, 260) to vibrate and atomize liquid stored in the negatively biased liquid reservoir (120, 186), the electrical signal comprising a current and a voltage; characterized by measuring, by a phase shift detector of the driver (152, 172, 210), a phase shift between the voltage and the current of the electrical signal driving the nebulizer (100-a, 100-c, 151, 178, 260); based at least in part on the phase shift of the electrical signal driving the element of the nebulizer (100-a, 100-c, 151, 178, 260) measured by the phase shift detector, determining, by a resonant frequency tracker of the driver (152, 172, 210), a resonant frequency of the element of the nebulizer (100-a, 100-c, 151, 178, 260) adjusting, by the driver (152, 172, 210), the frequency of the electrical signal to the nebulizer (100-a, 100-c, 151, 178, 260), wherein a near constant phase shift is maintained between the voltage and current of the electrical signal and the resonant frequency of the element of the nebulizer changes as liquid is atomized and the negative bias pressure within the sealed drug reservoir (120, 186) changes; and based at least in part on the resonant frequency of the nebulizer (100-a, 100-c, 151, 178, 260) determined by the resonant frequency tracker of the driver (152, 172, 210), determining, using a voltage profile of the driver (152, 172, 210), a voltage magnitude for the electrical signal at a particular resonant frequency to maintain consistent droplet size and dosing of the atomized liquid.