## 3 Typical Requirements of Implant Systems
Such encapsulation is detrimental to the ability of the electrode to sense signals, since it changes the diffusion properties of nervous tissue (rendering it less permissive) and increases impedance [71,80], increases the distance between the electrode and its nearest target neurons [74], and produces an inhibitory environment for neurite extension, thus guiding regenerating neural processes away from the electrodes [72,81]. Gliosis and enhanced formation of associated extracellular matrix molecules have been demonstrated to affect molecule diffusion, and as such, neuron-glia communication, \"cross-talk\" between synapses, extrasynaptic volume transmission, and tissue regeneration [80,82]. Even relatively small increases in the separation between the sensing surface and the nerve tissue may be highly detrimental to the ability of the former to detect a signal, since to adequately sense the neuronal spikes and local field potentials, the distance between the neuronal ensembles and the target neurons should be within \(\sim\)50 \(\upmu\)m [77]. Local field potentials hold key information regarding functional behavior of neural networks that correlates with disease symptoms, and can therefore be used as a biomarker [50]. Communication technologies used for data transfer to and from the indwelling device should support high data rate, data latency, data accuracy and adequate data security, be reliable, and consume minimal power [5]. The advancement of implantable devices used for sensing and stimulation resulted in a considerable upsurge in the density of analysis and interpretation algorithms, consequently contributing to the complexity and length of follow-up observations [37]. The extended battery life and the increasing longevity of patients with indwelling medical devices further add to the ever increasing number of implant carriers in follow-up. Given the limited amount of time and resources available to medical practitioners, conventional follow-ups are followed by long periods of time when medical personnel receive very little or no data on the wellbeing of the patient or the performance of the indwelling module [83]. As a consequence, technologies that enable remote interrogation of indwelling medical devices are attracting much attention [84]. Wireless remote monitoring facilitates collection of technical information regarding the performance, attributes and settings of the implanted module, as well as the physiological parameters of the treated individual, and the outcomes that result from the treatment [85]. The obvious benefits include the ability to promptly respond to the changes in the clinical status of the patient, and minimize potentially harmful effects of implant malfunction or failure; and ability to monitor the effectiveness of the treatment and alter the stimulation parameters based on the data obtained. Furthermore, remote monitoring can effectively lessen the weight of in clinic follow-up on the healthcare system, while maintaining or improving on the existing patient safety standards [37]. The continuous stream of data can enhance the power of large-scale population health bio statistical analysis, and thus contribute to the improvement in the quality of life of the population.