A major challenge in brain-computer-interfaces is the development of technology that integrates well with the brain without sacrificing device functionality and implantability. Currently, the only commercially available device for humans is the Utah-array. However, the stiffness and size of these silicon probes have an adverse effect on the brain tissue, which decreases the interface longevity. In this project we investigate different probe designs to determine which parameters are most important to improve device-tissue integration, focusing on the rigidness and the footprint of the probe. Rigidness is determined by the probe material (stiff vs flexible) and the implantation technique, as probes tethered to the skull do not follow the micro-movements of the brain. The footprint of the probe, defined by its thickness and width, directly impacts the lesion in the brain and influences the immune response. We implant a total of 102 probes of varying cross-section in 34 mice, divided into groups based on probe material (silicon vs polyimide), implantation technique (tethered vs untethered), and implantation duration (6 vs 12 months). This study focuses on the histological analysis of brain slices depicting lesions. We investigate the tissue based on 1) the lesion size caused by the implant, 2) the immune response expressed by astrocytic and microglial reaction, and 3) the neuronal loss around the lesion. Preliminary results show an advantageous biocompatibility of probes with smaller width and thickness, causing a reduced reaction in the tissue. This study gives important insights on optimizing device design parameters for improved tissue integration.