We present computational simulations based on physics equations of the expected performance by a nanodevice that would play the role as an immune system cell such as the well-known macrophage, in the sense that these advanced devices can detect and perform interventions against aggregations of bacteria or virus. These prospective nanorobots would have the capability to recognize physical properties as well as to anticipate motion of bacteria and virus based entirely in electric interactions. The recognition of the type of bacteria is achieved through the continuous sensing of the electric interactions between the nanorobot and bacteria. A physics-based model entirely developed from the calculations of electric forces supports the content of this paper.