Abstract: Methods, apparatus and systems are described as relating to electrostatic sensors for detection in micro or nano electromechanical systems. In exemplary embodiments, a sensor for detecting a threshold value of is provided. The sensor includes a deformable member with a mass detection area, an electrostatic actuator having first and second plates, the first plate being connected to the mass detection area, and a voltage source connected to each of the first and second plate. The operating voltage being proximate to a local bifurcation point of the electrostatic sensor for the first and second plates to pull-in together. Upon an external mass having the threshold value appearing on the mass detection area, the local bifurcation point of the electrostatic sensor is shifted such that the first and second plates will pull in to contact each other by movement of the deformable member to signal detection.