## 2 Materials and Methods  
The Smart Capsule is composed of a mechanical container in polyurethane, dedicated electronics, and the Spoke platform, composed of backend software, an app, and the electronic firmware of the Smart Capsule. In order to implement the basic needs of the Smart Capsule in terms of materials and manufacturing need, polyurethane material was selected after evaluating preliminary prototypes in carbon. The used materials are available off-the-shelf and were manufactured according to high-quality standards based on the design of the device. Some parts were manufactured out of metal for structural reasons (aluminum, steel) leaving room for weight reduction in future prototypes. The design takes into account the possibility of integrating a dedicated electronics board and antennas. The mechanical interface of the drone has been manufactured out of aluminum to provide suitable mechanical resistance. The Smart Capsule is a container with the following features:  
* Autonomous flight control: no need for trained ground pilots;
* Fits all professional drones available on the market, as long as they comply with drone technical requirements (e.g., 10 kg load capacity, 60 km/h minimum speed, water and wind proof) and is adaptable to the continuous evolution of drones thanks to a dedicated adjustable interface;
* GPS/GSM/3G/4G connectivity to control the drone anytime and anywhere. The connectivity allows to modify the flight according to flight authorization requirements. The connectivity also guarantees the recovery of the active control by drone operators in case of emergency. The connectivity is provided with a SIM7600 module (SIMCom, Shangai, China). * Temperature and humidity sensors for real-time monitoring and control of storing conditions and quality of the medical freight, as prescribed by blood delivery regulations;
* Flexible and modular, able to adapt to any medical product (e.g., blood bags, organs, drugs, test samples). The Smart Capsule is internally equipped with a certified UN3373 container equipped with temperature stabilizers that, together with the polyurethane envelope of the Smart Capsule, contribute to maintaining proper temperatures. The temperature stabilizers are cooled in order to reach a suitable temperature (4 \({}^{\circ}\)C, 22 \({}^{\circ}\)C, \(-\)25 \({}^{\circ}\)C) before being inserted, together with the medical material, in the UN3373 container before every flight. Their action plus the thermal-insulated material of the Smart Capsule make temperature stabilization possible for about 3 h, which is a more than suitable time for one delivery mission. The Smart Capsule is shown in Figure 1 together with a certified box for diagnostic blood delivery. The Smart Capsule is designed for the delivery of blood and blood components, fulfilling stringent blood regulation, i.e., 4 \(\pm\) 2 \({}^{\circ}\)C for red cells, 25 \(\pm\) 2 \({}^{\circ}\)C for blood platelets, and \(-\)25 \({}^{\circ}\)C for frozen plasma. Different capsules could meet the requirements of other medical product delivery operations with less stringent regulation, such as test samples, equipment, and other products (still with temperature needs of 4 \({}^{\circ}\)C). The transportation of organs will be carried out by means of a specific internal certified container and by adjusting the temperature. The Smart Capsule is designed to be in full compliance with EU Directive 2002/98/EC prescribing quality and safety standards for the collection, testing, processing, storage, and distribution of human blood and blood components, and the smart capsule is UN3373 certified. The temperature stabilizers are made of HDPE and contain a solution of water and paraffin mixtures, available off the shelf (provided by Rixlab, Gualdo Tadino, Italy). These modular stabilizers have been chosen as the best compromise for transportation and storage at a constant temperature of heat-sensitive products, such as blood components, diagnostic samples, drugs, etc.