Ultraminiature single-crystal sensor with movable member

A miniature transducer, comprising:

• an adjustable capacitor including first and second electrically conductive members arranged in predetermined normal, physical relation to one another, with the first conductive member being a generally flat member, and the second conductive member being movable relative to the first conductive member;
• and
• an integrally formed structure made from single-crystal silicon semiconductor material, the structure having a flexible member and a support portion that extends at least around at least a part of the periphery of the flexible member, and mechanically supports the flexible member in a nominal position a predetermined distance from the first electrically conductive member,
• the flexible member and support portion being electrically conductive and heavily impregnated with at least a first material which alters an etching characteristic thereof in comparison to single-crystal material which is identical to the heavily impregnated material of the flexible member and the support portion except for containing substantially less of such first material;
• the flexible member constituting the second electrically conductive member of the capacitor, and being sufficiently thin in at least one selected region thereof relative to its overall size to allow the flexible member to move in response to a force applied thereto in a range designed to be measured by said transducer, whereby the movement of the movable member changes the capacitance of the capacitor.

A miniature force-sensing device having a capacitance which is adjusted by changes in a force to be sensed, comprising:

• a support substrate;
• and
• an integrally formed structure made at least primarily of single-crystal silicon material, the structure including (1) a first selected portion constituting a substantially rigid support structure bonded to the support substrate, the first selected portion being impregnated with a first material in a desired first concentration sufficient to alter an etching characteristic of the first selected portion relative to identical single-crystal silicon material containing substantially less of the first material, and (2) a second selected portion constituting a movable member supported by and capable of movement relative to the support structure, the second selected portion being impregnated with a second material in a desired second concentration sufficient to alter an etching characteristic of the second portion relative to identical single-crystal silicon material containing substantially less of the second material;
• and
• a force-sensitive adjustable capacitor having first and second electrically conductive plates normally spaced apart from one another, the first electrically conductive member including a generally flat conductive plate supported by the support substrate, and the second electrically conductive plate being at least in part supported by and movable with the movable member, whereby the capacitance of the capacitor is adjustable in response to movement of the movable member by a force applied thereto.