## 3 Development of a Video Otoscope with an Integrated Scanner: A Low-Cost Approach
### Video Otoscope Prototype  
Due to its versatility, fused deposition modeling (FDM) was the additive process selected to produce the various parts of the developed system. Figure 3 shows the developed prototype, and Table 1 shows the printing conditions used, including the USB camera connected to the Raspberry Pi. Figure 3: Prototype of the video otoscope support: (**A**) device overview and (**B**) video otoscope positioning detail. Images were collected using a USB camera intended for ontological inspection to validate the device developed from a functional point of view. This camera, characterized by its simplicity and portability, was connected to a Raspberry Pi microcomputer (the control and processing unit). The selection of these components aimed to achieve a balance between low cost, flexibility, and efficiency in acquiring the images necessary to validate the developed device. A simple program was developed in Python (Python 3.11 with Library NumPy 2.0.0 and OpenCV-Python 4.10.0.84) to facilitate camera operation and image acquisition. The program allowed the camera to be controlled effectively, capturing images directly on the Raspberry Pi 5. This automated process simplified data collection, reducing manual intervention and ensuring greater consistency in results. Figure 4 illustrates examples of the collected images for different EECs: (A) EEC #1 and (B) EEC #2. The 3D CAD model (Figure 5) is then built by superimposing, according to a reference system, the various 2D images captured at different angles, thus allowing a reliable representation of the geometry of the patient's ear canal. The images are then processed by specialized 3D reconstruction software, which uses computer vision algorithms to generate the 3D CAD model of the ear canal, as mentioned before. Once the 3D reconstruction is obtained, the model can be used to produce custom hearing aids. This process begins by converting the digital model into a file suitable for 3D printing, such as an STL file. From this file, a 3D printer produces a physical mold that precisely replicates the anatomy of the patient's ear canal. Depending on the material used in printing, the mold can be used directly or as a base to manufacture devices such as hearing aids or ear protectors. This approach brings great advantages, such as greater precision in adapting the hearing aids to the ear canal and consequent increase in comfort and effectiveness for the patient. Furthermore, the use of 3D printing allows for rapid and personalized production, reducing the time between diagnosis and availability of the hearing aids to the patient, in addition to increasing their quality, considering that the adjustment is based on the specific anatomy of each individual patient. \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Extrusion** & **Bed Temp.** & **Extrusion** & **Print Filling** & **Layer Height** & **Nozzle Diameter** & **Total Printing** \\
**Temp. (\({}^{\circ}\)C)** & (\({}^{\circ}\)C)** & **Speed (mm/s)** & **(\%)** & **(mm)** & **(mm)** & **Time (hrs)** \\ \hline
210 & 60 & 300 & 15 & 0.2 & 0.4 & 5.22 \\ \hline \end{tabular}
\end{table} 
Table 1: Control parameters for 3D printing by FDM. Figure 4: Example of image acquisition for different external ear canals (EECs): (**A**) EEC #1 and (**B**) EEC #2. Having technically validated the functionality of the developed device, it is now necessary to determine the receptivity of its use by the medical team and patients. In the following section, validation tests for the proposed video otoscope will be described and analyzed based on the responses from surveys conducted with speech therapists and patients. These validation tests involved both the evaluation of the technical performance of the video otoscope and the users' perception regarding its comfort and ease of use during the examination. These tests covered a diverse set of conditions, including analyzing the adaptability of the equipment to different ear morphologies.