In this paper, a new architecture for developing plasmonic bio-sensors is proposed in which sensing is achieved through optical beam steering. The proposed structure consists of an array of nano-antennas that generate an outcoming optical beam whose direction varies when the material under test or its volume changes. This mechanism of sensing eliminates the requirement for complex instruments such as optical spectrum analyzers. For realization of the proposed bio-sensor, both 1-D and 2-D configurations for the nano-antenna array are designed and numerically studied. The full wave numerical simulation results show that the designed bio-sensor provides a very high sensitivity of 33∘ per unit refractive index, and also the output light has an enough intensity to be observed by a naked eye. The final results show that although both versions have the same sensitivity, the 2-D structure can project the results with much higher intensity. It is also theoretically shown that the performance of the biosensor will be subject to the size of the array, and therefore, a practical large-scale version of the numerically studied structure would significantly outperform the simulated structure.