The first step of our innovation process consisted of an immersion phase. For a better understanding of our subject, we had to:
-document the state of the art, recording and analyzing existing or inspiring initiatives, actors, and institutions;
-meet with diverse experts, from associations (ADEPA, Figure 1) to industries (I.CERAM, Figure 4), through national institutes (CERAH, Figure 3) or hospitals (Georges Pompidou hospital, Paris Figure 2);
-identify specific literature and technical documents regarding existing prostheses;

This step led us to understand amputees' daily life (behaviors, psychology, life environments, healthcare system, economic resources, etc.) and to specify the main issues (such as bacterial infections) and challenges to address in order to propose the amputees relevant and effective innovations. These contents (data, testimonies, etc.) have been collected thanks to human and social tools (semi-directive interview grids), design tools (mood boards), and documentation tools (photography, video, sound recording).

After identifying knowledge, references, issues and constraints, we started a problem solving process by sketching first ideas, thanks to design tools, such as:
-brainstorming and post-it sessions (Figure 1), to write down the first ideas
-cartographic and mind-mapping tools, to structure ideas
-sketching, user journey and roadmaps, to give form to the first concepts.

Based on the previous steps and on our network of experts, we filtered generated-ideas in order to keep only the more adapted and relevant solutions regarding amputee’s behaviors, habits, psychology, life environments, economic resources, etc.

To jump from the first ideas to tangible solutions, we designed a complete system (hardware and software solutions) including:
- an implantation stem featuring our engineered biofilm
- a device making the bridge between the stump and a bionic prosthesis, to collect and process the signal from nerves
- a charging station, to recharge the device and synchronize data with a distant server
- an app / website, to monitor information, such as device’s battery level, health status, etc.

In order to design these solutions in a relevant, feasible and comfortable way, we payed strong attention to the device dimensions, ergonomics, assemblies, materials, colors, looks and feel, electronic parts, production process and costs. The following devices have been conceived and developed throught design and engineering knowledge. Skills and tools (McNeel Rhino 3D (Figure 1) for 3D modeling, Luxion Keyshot for 3D rendering), as well as scientific and industrial advice from experts were also used. Colors, materials and finishes have been chosen regarding our device's constraints, material databases and color charts (Figure 2 and 3).

We designed a fully functional stem (Figure 4 and 5) composed of:
- a biocompatible tube made of titanium TA6V4, to mechanically assemble the device to the user’s stump (1). This material have been chosen instead of stainless steel 316L thanks to the mechanical modeling of the 3D representation of a humerus bone with a prosthesis (Download the mechanical modeling here)
- a porous ceramic part (2), surrounding the metallic tube inside the amputee’s bone (3) to durably and safely link the tube to the bone
- our engineered biofilm (4), surrounding the metallic tube inside the amputee’s stump flesh
- a nanoporous membrane made of PEDOT: PSS (5), to confine the biofilm within our system, to fixate nerves on it, and to allow the ionic current from nerves to be transformed into an electrical current, that would be processed and used to actuate a bionic prosthesis
- a thin structure (6) that supports the nanoporous membrane and transmits electric current from nerves to the stem (7, 8).

We designed an ergonomic and functional device (Figure 6) to link the stump to a bionic prosthesis, composed of:
- a three parts plastic case made of light-weight, heat and shock resistant injection moldable plastic (ABS - Acrylonitrile-Butadiene-Styrene), to safely enclose technical parts. Injection molding is a reliable process that permits a low cost mass production. Two removable shells (1) surround the main structure (2) to facilitate maintenance. An elastomer seal (3) is placed between these parts and make the device waterproof. Moreover, plastic have been textured to make user’s daily interactions with his device easier
- a antibacterial ceramic shell (4), placed between the stump and the device, to improve hygiene and to protect the user from friction
- electronic parts, to amplify and process the signal (5), to charge the device (6, 7, 8), to store (9) and to send data (10).

We designed an easy to use charging / synchronization station (Figure 7), composed of:
- a plastic case (1, 2) made of ABS, to safely enclose technical parts
- electronic parts, to charge the device thanks to induction (3) and a USB-C plug (4), to send and receive data via wifi and bluetooth connection (5), to save data via a micro SD card (6), to demonstrate the charging and synchronization process via a LED ring (7)
- an elastic strip (8) placed at the back of the charging station, to store cables during transportation.

We designed an efficient system to allow our device to securely exchange data with the digital world. Integrated electronic parts and the designed digital architecture permit data from nerves signals, bionic prosthesis movements, and user’s health status can be recorded, stored and exchanged. An online algorithm would learn from the user on a daily basis, and improve future interactions. To do so, our communication system (Figure 8) is composed of:
- Bluetooth Low Energy, a very energy-efficient technology enabling heavy data transfer on short distances, to share daily stored data from the device to the charging station, and vice versa
- Wifi connection, to exchange those data with the distant secure NeuronArch servers, and vice versa.

Finally, we designed an app / website to create a user friendly interface. This app / website allows every NeuronArch user to store, monitor, understand, and share with a doctor his personal data. To do so, our app / website (Figure 9) is composed of:
- a personal home page (1), to have a general overview regarding health data, charging level, and general notifications
- a personal dashboard (2), to monitor recorded health data such as glycemia, blood pressure, etc.
- a medical appointment booking platform (3), including registered primary doctor availabilities, prosthetists locations, etc.
- a unique QR code (4), to securely share recorded personal data with the user’s doctors during appointments.

Once our solution digitally designed, we had to prototype both the device and the app in real. Rapid prototyping tools, such as 3D printers (FormLabs Form2 (Figure 1), FormWash, FormCure, and Ultimaker 3), laser cutting (Trotec Speedy360), and hands-on work (sand (Figure 2 and 3), assembly, paint, finishes, etc.), allowed us prototyped the device. Digital prototyping tools, such as desktop publishing softwares (Adobe Photoshop, Adobe Illustrator, Google Gallery), helped us to make the app and the website. This step helped the team to check and validate products dimensions, ergonomics, looks and feel.

Designing a strong visual identity is a key element in NeuronArch’s communication. Desktop publishing software (Adobe Photoshop, Adobe Illustrator, Adobe InDesign, Adobe PremierePro, Adobe After Effect), enabled us to conceive a global graphic chart easy to understand for users and the general public. This visual indentity includes iGEM Pasteur Paris 2018 logotype, NeuronArch logotype, pictograms, banners, graphic composition and color gradients both for print and digital medium. All these elements have been applied to printed formats such as flyers, communication posters and scientific posters, as well as digital formats such as NeuronArch app and website, wiki, etc. Professional photographic tools (Nikon D3200, Profoto flash kit, Manfrotto background) have been also used to create NeuronArch’s user scenario photographs.

Figure 1: Presentation of our visual identity