An omnidirectional accelerometer device comprising: a piezoelectric sensor element comprising a mass-supporting platform and a plurality of mass-supporting arms for a plurality of electrically distinct sensor electrodes, each of the mass-supporting arms extending from the mass-supporting platform, and each of the mass-supporting arms having one of the sensor electrodes formed thereon, the piezoelectric sensor element defining a hole; a connecting rod having a mounting end, a mass end, and a longitudinal length defined between the mounting end and the mass end, the mounting end being coupled to the mass-supporting platform, the connecting rod passes through the hole of the piezoelectric sensor element and the connecting rod comprises a threaded bolt; and a proof mass coupled to the mass end of the connecting rod, wherein acceleration of the proof mass causes deflection of the mass-supporting arms, which generates distinct sensor signals at the sensor electrodes, and the proof mass includes a threaded hole for threadably engaging the threaded bolt of the connecting rod; wherein: the longitudinal length of the connecting rod is tuned in accordance with a predetermined parallel acceleration sensitivity for the omnidirectional accelerometer device; the height of the proof mass along the connecting rod is tuned in accordance with a predetermined parallel acceleration sensitivity for the omnidirectional accelerometer device by threading the proof mass onto the connecting rod to reach a desired height for the proof mass relative to the mass-supporting platform; each of the sensor electrodes has a longitudinal sensor length along its respective mass-supporting arm, the mass-supporting arms including two vertical mass supporting arms that are smaller than two horizontal mass supporting arms; and the longitudinal sensor length is tuned in accordance with a predetermined perpendicular acceleration sensitivity for the omnidirectional accelerometer device. a piezoelectric sensor element comprising a mass-supporting platform and a plurality of mass-supporting arms for a plurality of electrically distinct sensor electrodes, each of the mass-supporting arms extending from the mass-supporting platform, and each of the mass-supporting arms having one of the sensor electrodes formed thereon, the piezoelectric sensor element defining a hole; a connecting rod having a mounting end, a mass end, and a longitudinal length defined between the mounting end and the mass end, the mounting end being coupled to the mass-supporting platform, the connecting rod passes through the hole of the piezoelectric sensor element and the connecting rod comprises a threaded bolt; and a proof mass coupled to the mass end of the connecting rod, wherein acceleration of the proof mass causes deflection of the mass-supporting arms, which generates distinct sensor signals at the sensor electrodes, and the proof mass includes a threaded hole for threadably engaging the threaded bolt of the connecting rod; wherein: the longitudinal length of the connecting rod is tuned in accordance with a predetermined parallel acceleration sensitivity for the omnidirectional accelerometer device; the height of the proof mass along the connecting rod is tuned in accordance with a predetermined parallel acceleration sensitivity for the omnidirectional accelerometer device by threading the proof mass onto the connecting rod to reach a desired height for the proof mass relative to the mass-supporting platform; each of the sensor electrodes has a longitudinal sensor length along its respective mass-supporting arm, the mass-supporting arms including two vertical mass supporting arms that are smaller than two horizontal mass supporting arms; and the longitudinal sensor length is tuned in accordance with a predetermined perpendicular acceleration sensitivity for the omnidirectional accelerometer device.