# Applications of the Open-Source Hardware Arduino Platform in the Mining Industry: A Review
## 3 Arduino in Wearable Systems
### Human Bioinformation  
Human bioinformation refers to information related to the status of human health, such as heart rate/pulse rate (hereafter heart rate), blood pressure, glucose level, and electrocardiogram data. In fact, these types of biosensors have expanded with the increasing demand for human health monitoring. These sensors can continuously provide data on human health status, and thus, people can prevent disease. A heart rate monitoring sensor is frequently used to measure the electrical activity of the heart. The main purpose of most studies addressing human bioinformation reviewed in this section is to monitor the heart rate using a sensor. This is because gas leakages, oxygen concentration reductions, and rapid temperature and humidity changes in underground mine environments can adversely affect the health of mine workers. Naturally, the proposed wearable systems also include functions for measuring air quality or detecting collisions in underground mine environments. Wearable systems for connecting the heart rate sensors used in the mining industry with field monitoring systems or unmanned aerial systems are difficult to develop. Furthermore, unlike systems that collect surrounding information, e.g., in the case of a wearable system for measuring human bioinformation, an actuator is configured so that the measured data is always transmitted to a supervisor or a ground control station, to check the status of the miner in real time (Figure 9). Recently, many researchers have proposed wearable systems for connecting heart rate sensors, to check the heart rates of miners working in underground mines. Herein, these studies are classified according to the type of actuator, such as data transmission to a control center, vibrating belt, or helmet with both alarm and data transmission functions. [PERSON] et al. [64] developed a LabVIEW-based real-time heart rate monitoring kit for coal mine workers. They connected an ECG sensor (AD8232) to an Arduino UNO board (ATmega328) to check the electrical behavior of the heart. The ECG sensor pad was attached to human skin (e.g., the wrist or elbow) and measured the biopotentials produced by the heart (electrocardiogram) or other biopotentials from the human body. The device monitored the heart rates and analyzed the health conditions of workers using LabVIEW software. LabVIEW was used as an integration platform for acquiring, processing, and transmitting the data in the study. The analyzed data could be continuously monitored by the authority of the control station. If a worker was suffocating owing to an abnormal mining environment, a webpage would immediately pop up. LabVIEW continuously compared the sensed value with the predefined threshold limit value, and then provided an alert indication signal according to the heart rate of the worker. Via LabVIEW, the processed data could be transmitted to servers or webpages. [PERSON] et al. [65] proposed a design for a wireless mine surveillance system using Arduino and ZigBee (XBEE) technology. They measured not only the gas concentration using the MQ35 sensor, temperature, and humidity using a DHT11 sensor, but also the heart rate, based on an IR light reflection and refraction approach. The heart rate sensor was based on the Lambert-Beer Law and obtained the pulse rate using tactile measurement. The logged data were transmitted via a ZigBee module (Xbee transmitter), and a control room at a ground station received them via another ZigBee module (Xbee receiver). Thus, the proposed system not only monitored all types of parameters under the coal mine, but could also provide an automatic alarm when environmental parameters exceeded their limitations, helping to improve the level of monitoring safety in production and to reduce accidents in coal mines. [PERSON] et al. [66] developed a prototype vibrotactile belt for navigation in an underground mine with heart rate monitoring. Unlike the aforementioned studies, this system did not consider air quality, collisions, or destructive event detection in the underground mine.