A taut wire perimeter fence intrusion detection system is disclosed. The taut wire deflection sensors in the system each include a flexible housing into which is disposed a full resistance bridge having strain gages for each leg. Opposing strain gages in the bridge circuit have predominant directions in common directions. The strain gages are formed directly onto a printed circuit board. An amplifier circuit is also mounted onto the circuit board, for amplifying the differential bridge voltage from the bridge. The taut wire is connected to the housing, for example by way of a slotted bolt and nut, so that horizontal deflection of the taut wire creates strain on the circuit board which is sensed by the strain gage bridge, amplified by the amplifier, and communicated to a data processing system which generates the appropriate alarm condition.