A surgical instrument system comprising a handle assembly is disclosed. The handle assembly comprises an actuation trigger comprising a curved proximal portion and a curved cylinder surrounding the curved proximal portion of the actuation trigger. The curved cylinder comprises an electroactive polymer. The surgical instrument system comprises an actuation rod which is configured to transmit an actuation force and a sensor system which is configured to detect the magnitude of the actuation force. The electroactive polymer is responsive to the actuation force and provides feedback to a user of the surgical instrument system.