The present disclosure provides an apparatus for harvesting stem cells from fat tissue. The apparatus may include a first transducer coupled to a first end of an resonant horn to form an ultrasonic resonator. The resonant horn may include an elongated body having a plurality of through-holes configured to accommodate a plurality of specimen containers that are positioned substantially perpendicular to the elongated body. The apparatus may also include a wave generator coupled to the first transducer to generate an ultrasonic wave, wherein the elongated body has a length that is multiples of the half-wavelength of the ultrasonic wave.