## 2 Theoretical Background and Related Works
### Types of Hand Wearable Device  
The concept of wearable intelligence has been broadly explored in the past decades. Numerous emerging technologies offer convenience to daily human life, especially for old and disabled people [94]. The adoption of hand wearable devices is not new to our world. Hand data gloves are applied in various study domains, including medical surgery, game, virtual reality, and shopping applications [95]. Data gloves achieved a high accuracy rate suitable for medical surgery. In gaming, gestures are the most interactive module for game control. Even iPods, iPBones, or iPads use gestures on mobile video game platforms. Gestures must be recognized first, and hence the data glove is employed. The data glove is designed to replace static and fixed keyboards and mice to promote a sense of immersion. It permits users to interact with the computer more authentically and naturally [96]. In the aspect of rehabilitation, the hand wearable device is of utmost importance. A research project revealed that the incidence of strokes has risen twofold in low-income and middle-incomecountries in the last three decades [97]. Stroke is the primary cause of physical disability. After having a stroke, complications such as upper limb hemiparesis are common [98]. Stroke patients can use smart gloves outside of the therapy clinics without supervision by therapists or healthcare providers. Researchers have explored adopting state-of-the-art techniques to enable hearing and speech-impaired people to communicate and build ties with others. A sensory glove can collect and record information for dynamic and static signs to facilitate the accuracy of sign language or gesture recognition in real-time and interpret the meaning into words [95]. Therefore, the invention of wearable hand devices such as data gloves provides a more natural and resultful approach to communication, particularly for people with special needs. Furthermore, wearable hand device usage is being explored continuously to bring humankind convenience.  
Hand Wearable Devices Related to Safety and Health  
Nowadays, safety and well-being at work should be recognized as urgent affairs for numerous industries. Wearable devices are one of the most hopeful solutions to eliminate or mitigate the hazard of mental and physical accidents in the working environment. Organizations are broadly employing wearables to perform different tasks to improve workplace safety [67]. Hand wearable devices are one practical example of wearables for OSH monitoring. In the high-temperature workplace, protective gloves can release heat-related warnings and alert messages to support and protect firefighters or workers [93]. The embedded wireless system in protective gloves consists of an analog temperature sensor for observing temperature on the opisthenar of a worker, a barometer for detecting the changes of atmospheric pressure, and a thermocouple for measuring contact heat as well as providing haptic feedback in the event of risky situations by miniature vibration motors that are embedded in the flexible part of the glove. Thus, this powerful hand wearable device has emerged for substituting occupational risks, injuries, and diseases [99]. Latent hazards such as workers located in a dangerous area, the worker being under high physical demands or fatigue, and the danger of worker exposure to musculoskeletal disorders can be effectively avoided or lessened by inferring from the collected information [100]. Therefore, the advanced sensors and technologies offer plenty of chances for real-time monitoring to maintain adequate workplace safety and health management and identify OSH risks through timely feedback. Since OSH is a global priority, the potential of hand wearable technology will enable a new path toward maintaining OSH. Adopting hand wearable electrons in the workplace is being promoted to uplift employees' health and well-being. In conclusion, occupational hazards can be identified, reduced, eliminated, and controlled.