## 2 Chameleon-1 Helmet Design (Neuro-Electro)  
Based on the literature review, the design of this innovative technology focused on the health area has great scientific and technological contributions. The design of the Chameleon-1 helmet is compatible with most skull sizes, since it can be sized to different lengths and allows mobility on all its electrodes without affecting the signal acquired by the sensors. Most helmets found in the literature are limited in size and have poor ergonomics, and the electrodes remain fixed in one position. Likewise, certain devices developed have electrodes and an electronic card near the patient's forehead, and this can cause interference in the acquired signals. The design of the Chameleon-1 helmet has all the electronics located at the back of the head to reduce possible interference in the EGG signals and to obtain a better result in the reading and storage of electrical signals from the brain. The Chameleon-1 helmet not only optimizes ergonomics and reduces interference but also incorporates materials that allow for precise flexibility and fit, adapting to various head shapes without compromising measurement quality. These materials include flexible conductive polymers that ensure the implementation of an ergonomically optimized design and an improved arrangement of the electrodes that allows obtaining a more precise and focused signal in the region of interest. The modular design of the headband, coupled with its mobility, enables the flexible integration of different sensor types, allowing for precise positioning and adjustment. One of the most innovative features of the Chameleon-1 helmet is its precise positioning of each electrode, allowing for real-time monitoring with accurate performance at measurement points based on the 10-20 system. This facilitates its use in non-laboratory environments, such as in field studies or at home, allowing patients or research participants to maintain their mobility and daily routine without interruption. The international 10-20 system is an internationally recognized method for describing the location of each electrode. The numbers 10-20 refer to the percentage (10 and 20) of distance at which the electrodes should be placed on the frontal, occipital, right, and left sides of the skull, as can be seen in Figure 1.  
One of the promising applications of the Chameleon-1 helmet is its ability to capture high-quality signals without the need for extensive patient preparation, making it an ideal tool for continuous therapies or prolonged sessions, such as the treatment of neurological therapies. Likewise, its portability, user-friendly design, and adjustable structure create new opportunities in neurorehabilitation by enhancing the adaptability, precision of EEG-based monitoring and therapeutic interventions. The design of the Chameleon-1 helmet is presented with the following views and describes each part:  
* Front part This region includes most of the elements that make up the mechanical part of the Chameleon-1 helmet (see Figure 2), which is a vitally important area for the design, highlighting its main function in the capture of electrical signals generated by neurons; among other functions, the innovative mechanism with great versatility for different skull sizes stands out. The front part of the helmet is made up of the following various pieces:  
1. Base: This part of the helmet is responsible for adhering to the skull (which surrounds it and is adjustable for all types of skull). Its function is crucial, since it constitutes the base of the helmet, taking into consideration the minimum average size of a skull 50 cm in perimeter, considering the skull as an ellipse. 2. Column: This is the vertical part that holds most of the helmet's weight, which is attached to the aforementioned base. This adjusts to any type of skull. It offers the necessary support and flexibility to provide enough firmness for prolonged use. 3.