A heat exchanger that is constructed with a heat exchanger shell having inlet and outlet plenums and fluid inlet and outlet ports, and a tube sheet construction disposed in the heat exchanger shell. The tube sheet construction includes at least two separate tube sheets and a plurality of tubes that extend between the separate tube sheets. Each tube sheet includes at least two planar tube sheet segments and a interstitial layer disposed between the at least two tube sheet segments, and at least one sensor element supported by each of the interstitial layers. A control monitor controls flow through the shell by a feedback control from the sensor to an inlet control valve and/or a stimulus device excites the media layer. In an alternate embodiment opposed position sensor elements may be provided at opposite sides of the tube sheet construction.