An apparatus includes a cantilevered element including a coating material having an affinity for at least one compound. The apparatus further includes a first capacitive plate and a second capacitive plate that are each spaced from and capacitively coupled to the cantilevered element. The first capacitive plate is configured to induce a vibration in the cantilevered element at a frequency related to a mass of the cantilevered element. A frequency detector is coupled to the second capacitive plate to detect a change in vibrational frequency of the cantilevered element as a result of at least one particle of the at least one compound coupling to the coating material.