In this work, a Diagonal Tunneling Dielectrically Modulated Tunnel Field Effect Transistor (DT-DMTFET) architecture is proposed for label-free bio-sensing application. The performance of this sensor architecture is comprehensively investigated with the help of extensive numerical device simulations. The architecture has been carefully engineered to exploits the diagonal band to band tunneling (BTBT) component in favor of bio-molecule detection. The essential physics of the transduction mechanism for lateral tunneling, vertical tunneling, and diagonal tunneling-based DMTFETs is extensively analyzed from device electrostatics and transport mechanisms. The transduction efficiency of the sensor devices is quantitatively assessed in terms of current sensitivity, where DT-DMTFET exhibits a sensitivity of 3590 compared to 2514 and 1550 observed in lateral tunneling (LT) and vertical tunneling (VT) dominated DMTFETs, respectively. The optimum sensitivity of DT-DMTFET is observed at 4V and 0.4 V gate and drain biases ranges of operation, where the same is observed at a gate bias of 5V and 7V for LT- and VT- DMTFET, respectively. Furthermore, the device design aspects are studied in detail to identify the relevant structural parameters and subsequently optimize the sensing performance of the DT-DMTFET. Finally, an extensive comparative performance study establishes that the DT-DMTFETs offer more than 50% and 100 % improvements in the current sensitivity compared to their lateral and vertical tunneling-based counterparts, respectively, over a range of bio-molecule sample specifications.