A force sensing resistor (FSR) that is constructed with a first substrate made of polyimide disposed underneath a second substrate that is resistive and flexible. A handheld controller for an electronic system may include the FSR having a first substrate made of polyimide. The FSR may be mounted on a planar surface of a structure within the controller body, such as a structure mounted within a handle of the controller body, and/or a structure that is mounted underneath at least one thumb-operated control that is included on a head of the controller body. The FSR may be configured to measure a resistance value that corresponds to an amount of force applied to an outer surface of the handle and/or an amount of force applied to the at least one thumb-operated control.