The acceleration data provided by a MEMS (MicroElectroMechanical System) IMU (Inertial Measurement Unit) (model MPU-6050, manufactured by Invensense Inc., San Jose, CA, USA), integrated into the chest band, are used to delete the motion artefacts. Any movement of the patient's body unrelated to breathing may induce some effects on the acquired signal, leading to errors in measuring the parameters of interest. Even when the user is sitting or lying down, the body's movements due to bending or twisting of the trunk can affect the signal provided by the strain sensor [17]. The chest band integrates a BLE transceiver for transmitting the derived breathing parameters to a host device, allowing the remote monitoring of breathing data through a custom mobile application. The main contributions of the proposed scientific work are:  
* Hardware and firmware development of a piezoresistive chest band to detect the breathing parameters using a custom textile-based strain sensor;
* Design of a custom mobile application for displaying the breathing parameters wirelessly transmitted by the chest band. * Comprehensive characterization of the developed device in measuring the RR in different operative conditions of the user (seated, standing, walking). We believe that band devices offer better performance in terms of ease and stability of the application than systems placed on or glued to the body, or applied on the face [18,19]. Unlike other similar systems, the proposed wearable device is fully wearable, compact, and non-interfering, and does not require any external devices to acquire and process the data from the integrated sensors, while nevertheless providing comparable performance. Therefore, it offers a ready-to-use solution for remotely monitoring the patients' health conditions. The remainder of the paper is organized as follows: the next section presents a brief overview of related works on wearable devices that employ piezoresistive and inertial sensors to monitor respiratory parameters. Section 2 introduces the architecture of the developed chest bands, describing the features and specifications of the components and materials used. In addition, the firmware development supporting the chest band's operation is introduced. Moreover, the mobile application used to monitor the breathing parameters transmitted by the chest band is described. Section 3 presents the characterization results of the chest band for different operative conditions. Section 4 discusses the obtained results, presenting the chest band's performance in measuring other breathing parameters and comparing them with a spirometer. In addition, the test results on patients with different characteristics (gender, age, physical constitution) are reported. Finally, a comparative analysis of the presented chest band with similar devices is presented, highlighting the strengths and shortcomings. Overview of Wearable Sensing Systems for Breathing Monitoring Based on Piezoresistive and Piezoelectric Sensors Strain sensors can be integrated into wearable devices that exploit diaphragm contraction and relaxation to measure cardiovascular data. Specifically, piezoresistive or piezoelectric sensors can be included in belts, and thus deformed by the chest expansion resulting from breathing, providing a voltage variation proportional to the movement [20]. In particular, in [21], the authors presented a chest band for monitoring the RR comprising a piezoresistive sensor integrated into a 3D-printed case enabling converting the breathing-related tensile force into a compressive force. However, the main constraints of wearable systems relate to their lightness, small dimension, and flexibility, so that the user's movements are not hindered [22]. For these reasons, several solutions are reported in the literature exploiting strain-sensitive textiles [23, 24, 25] and polymer-based materials [26,27].