SafeFire

Motivation

Wildfires are a recurrent global problem and the fire environments are highly demanding for firefighters. They have to face extreme temperatures under intense physical work, being exposed to toxic gases inhalation, trauma, burns, and other physiological risks. Nevertheless, among all these risks, heart failure is the main cause of on-duty deaths, something that is potentiated by the high prevalence of obesity, hypertension, and heart disease in the firefighters’ population.

Ambulatory electrocardiogram (ECG) monitoring could help manage teams in the field, by instantaneously detecting, or even forecasting, eventual fatal events. Ambulatory monitoring allows near-continuous health assessment, which is important because the stress conditions continuously change during firefighters’ missions and because some diseases’ features are only captured under specific conditions. The ECG, on the other hand, is capable of detecting most of the diseases’ features and much information can be extracted from it, dispensing additional sensors. But, how would be performed this ambulatory ECG monitoring? Through a Smart Garment! Smart garments appear as one of the potentially best solutions to continuously monitor an individual in a discreet manner. In fact, continuous monitoring under extreme environments and dynamic conditions is challenging, given that there is a trade-off between signal quality and user comfort. The purpose of smart garments is to provide the best balance between these two variables. Designing a smart garment that matches this balance is the focus of the master’s thesis of Edgar Varela.

Prototyping

The proposal for the smart garment is the Smart Firefighting Undergarment, composed of:

• A sleeveless shirt containing 3 dry electrodes (by Nanoleq) embedded.

• An acquisition system composed of a ScientISST CARDIO connected to a similar shape battery.

• An external pocket that is sewn on the shirt to house the acquisition system and keep it together with the shirt.

The SFU needs to be connected to a computer running the Sense Web, through Bluetooth (or Wi-Fi), in order to transmit the acquired ECG data. The data can be downloaded from SENSE Web after the acquisition ends.

The design of the shirt, like the location of the sewn pocket and the design of the acquisition system’s enclosure, aimed to provide the best comfort and practicality to the user. These specifications were optimized by crossing feedback on an experimental trial with firefighters. The sleeveless design, pocket location on the sternum, and flat enclosure design were the specifications that better promote comfort and mitigate conflicts with movements and other equipment.

Validation

The performance of the signal acquisition under dynamic conditions was assessed based on the electrode displacement (loss of contact between the electrode and the skin) frequency during an experiment with firefighters. Five promising leads were tested and benchmarked. The lead CS5 showed higher robustness in general, with more emphasis on arm motions. The leads CM5 and CC5 also showed satisfying performances, in particular on trunk motions (showing some complementarity with CS5).

The SFU showed also good robustness while working in real fire environments. The SFU’s structure and components withstood well the temperatures usually felt on firefighters’ skin surface (up to 50oC). The connection between the SFU and the ScientISST SENSE WEB did not show a significant loss of stability, despite the extreme heat, humidity, and steam present in the fighting environment.