Many bio-integrated electronics used clinically must maintain high levels of performance over extended periods of time. Longevity was especially challenging at the biotic interface, since the total device thickness is restrained to achieve low bending stiffness, and the space for device encapsulation is narrow. To address this grand challenge, I have developed a class of flexible active sensing matrix with a capacitively coupled sensing strategy. The whole device is covered with an ultra-thin thermally-grown SiO2 layer, serving both as the dielectric for capacitively coupled sensing, and as the barrier for device encapsulation. Experiments from accelerated testing suggest the potential for operation for many years while fully implanted. I have successfully applied this system into two areas: i) monitoring micro-electrocorticographic (µECoG) activity on the brain of none-human primate, and ii) mapping epicardial physiology on Langendorff-perfused rabbit heart model.