The overall goal of the Cleveland Open Source Modular Implant Innovators Community (COSMIIC) is to establish an open source, modular network of active implantable devices for use in early feasibility human research and to provide ongoing support for this technology through a vibrant, sustainable community of active users. Our team is poised to successfully achieve all of the goals of the HORNET program because our proposed concept is based on our established platform ecosystem, the Networked Neuroprosthesis (NNP). This provides a solid technological platform with known regulatory status for our COSMIIC HORNET project. Critically, all technology described in this proposal was invented by the investigative team and therefore we are able to fully embrace the open source ideology for the end-to-end technology. The proposed COSMIIC HORNET System, which will be established on the platform NNP System, is a system of interoperable and integrated modules that can simultaneously electrically activate, block, and sense throughout the body. The system can record and process electroneurogram (ENG), electromyogram (EMG), intracortical signals, electrocardiogram (EKG), kinematic variables, photoplethysmogram (PPG), and temperature. Each module can directly communicate with all other modules through an established network communication protocol. The system can process signals to implement complex closed-loop control without requiring non-implanted hardware. Importantly, the existing NNP platform components (power module, stimulator module, biopotential recording module, network cable, electrodes) already have IDE approval from the FDA and have been successfully implanted and implemented in human research participants. Thus, the COSMIIC HORNET System has the necessary features to provide the modular platform ecosystem for use by the bioelectronic community for the foreseeable future. Aim #1. Dissemination. We will establish the COSMIIC community with full open-source access to an established modular implantable device for use in the peripheral and central nervous system. Access will be given for all circuit designs and layouts; mechanical drawings for all enclosures and connectors and cabling; the annotated code for all operating software, firmware, and bootloader; written instructions and videos of fabrication techniques; and all regulatory documents and test data, including our approved IDE document. Aim #2. Sustainability. We will develop a sustainable open source model through the development of technology that attracts a broad investigative team to establish a critical mass of COSMIIC users. We will provide ongoing support of the technology and partner with commercial partners to create a sustainable business plan so that the COSMIIC community remains independently vibrant and active after three years.