  We propose a new type of a transition edge sensor based on an
Al/AlOx/Ti/AlOx/Al superconductor - insulator - superconductor - insulator -
superconductor (SIS'IS) structure. It exhibits sharp dependence of zero bias
resistance on temperature of the titanium absorber in the vicinity of its
superconducting critical temperature. We demonstrate temperature sensitivity of
the device to be $2\ \mu \text{K}/\sqrt{\text{Hz}}$. Noise Equivalent Power
(NEP) of the device, limited by the amplifier noise, is estimated to be
$4\times 10^{-17}\ {\rm W}/ \sqrt{\rm Hz}$ at 313 mK. The tunnel junctions
between superconducting leads should help to overcome the size limitation
imposed by proximity effect in conventional transition edge sensors, without
sacrificing the sensitivity. Besides that, the input resistance of the device
can be tuned in a wide range.
