Micromachined threshold pressure switch and method of manufacture

A pressure switch of the type having a first electrode spaced from a second electrode, the first electrode being moved toward and contacting the second electrode upon application of a threshold pressure to the switch, the improvement comprising:

• forming the first electrode spaced from the second electrode by (a) trapping gas in an enclosed cavity formed between a first working layer and a second working layer, wherein the first working layer is single crystal silicon, and (b) expanding the gas to generate pressure sufficient to bloat radially outward from the cavity at least the first working layer, the bloated first working layer forming the first electrode and the second working layer across the cavity forming the second electrode.

A pressure switch of the type having a first electrode spaced from a second electrode, the first electrode being moved toward and contacting the second electrode upon application of a threshold pressure to the switch, the improvement comprising:

• forming the first electrode spaced from the second electrode by (a) trapping gas in an enclosed cavity formed between a first working layer and a second working layer, and (b) expanding the gas to generate pressure sufficient to bloat radially outward from the cavity at least the first working layer, the bloated first working layer forming the first electrode and the second working layer across the cavity forming the second electrode, said expanding the gas including heating the gas above a temperature at which the first working layer plastically deforms.

A pressure switch of the type having a first electrode spaced from a second electrode, the first electrode being moved toward and contacting the second electrode upon application of a threshold pressure to the switch, the improvement comprising:

• forming the first electrode spaced from the second electrode by (a) trapping gas in an enclosed cavity formed between a first working layer and a second working layer, and (b) expanding the gas to generate pressure sufficient to bloat radially outward from the cavity at least the first working layer, the bloated first working layer forming the first electrode and the second working layer across the cavity forming the second electrode, said expanding the gas including bloating the first working layer in a manner such that the first working layer plastically deforms.

A pressure switch of the type having a first electrode spaced from a second electrode, the first electrode being moved toward and contacting the second electrode upon application of a threshold pressure to the switch, the improvement comprising:

• forming the first electrode spaced from the second electrode by (a) trapping gas in an enclosed cavity formed between a first working layer and a second working layer, (b) expanding the gas to generate pressure sufficient to bloat radially outward from the cavity at least the first working layer, the bloated first working layer forming the first electrode and the second working layer across the cavity forming the second electrode, and (c) covering the bloated first working layer with a layer for maintaining shape of the bloated first working layer such that the first working layer remains bloated until application of a threshold pressure to the switch.

A pressure switch of the type having a first electrode spaced from a second electrode, the first electrode being moved toward and contacting the second electrode upon application of a threshold pressure to the switch, the improvement comprising:

• forming the first electrode spaced from the second electrode by (a) trapping gas in an enclosed cavity formed between a first working layer and a second working layer, and (b) expanding the gas to generate pressure sufficient to bloat radially outward from the cavity at least the first working layer, the bloated first working layer forming the first electrode and the second working layer across the cavity forming the second electrode, and the bloated first working layer exhibiting mechanical hysteresis by (a) collapsing from an initial bloated shape to contact the second working layer in response to application of a first threshold pressure, and (b) subsequently returning to the initial bloated shape in response to a decrease of applied pressure to the second threshold pressure, the first working layer remaining collapsed for applied pressures between the first and second threshold pressures.