## 1 Introduction  
Humans have always been seeking more and more improvements in their natural sensing and physical characteristics. These improvements could be associated with some cognitive evolutions caused by the human instinct to adapt to new changes in living environments. Due to the exponential growth in the complexity machine structures and the consequent need for interaction between the functionalities of machines and human sensations, human-machine interfaces (HMIs) were born [1, 2, 3]. This has led to a new era of virtual reality (VR) and augmented reality (AR), where humans can interact with machines through specially designed smart interfaces [4, 5, 6]. Haptics or haptic technology reproduces the touch feeling during the interaction with a real-world or virtual environment [7, 8, 9]. Teleoperation, the term for remote physical interaction, refers to using computer software to interact with a virtual world [10, 11, 12]. Thanks to the fast advancement of technology in recent years, the design of haptic deviceshas increased tremendously. However, multidisciplinary competencies are required for designing haptic interfaces, including computer sciences, software design, electronics, communication, electromechanical design, and ergonomics [13; 14; 15]. The haptic interface comprises a manipulator acting as a mediator between humans and simulations and continuous visualization of virtual or remote environments. The user moves around in the virtual or remote environment by manipulating the robotic equipment. Computer simulations of different activities may convey lifelike, tactile feelings to a user using haptic feedback, consisting of mechanical feedback in a human-machine interfacing system [16; 17]. Haptic feedback enables things generally visualized to assume real physical characteristics such as mass, hardness, and texture. Haptic interfaces can improve production evaluation in computer-aided design and manufacturing (CAD/CAM), design prototyping, and letting people handle virtual products before producing them. Furthermore, haptic interfaces can be useful for training and education purposes, for instance, in surgical procedures or to simulate activities carried out in dangerous environments, enabling the optimization of and improvement in personal skills [18; 19]. Haptic interfaces can also deliver force feedback while teleoperation procedures, such as telesurgery or hazardous waste clearance, are being carried out remotely. The advantages of haptic feedback are obvious, given the variety of uses. These technologies are discussed in detail in this work; specifically, an analysis of haptic feedback interfaces, one of the many principal vectors in HMIs, has been conducted. It will also be discussed how reliable these systems are in applications fields such as healthcare (physical rehabilitation, smart virtual elderly healthcare, etc. ), communication devices for disabled or deafblind people, entertainment, and VR and AR applications. After describing the human tactile sensation and analyzing the overall anatomy of the various mechanoreceptors in the human skin, the principal haptic interfaces are classified according to the main effect that defines their functionality in terms of haptic feedback. Then, a comprehensive account of the state of the art of wearable haptic interfaces is presented, comparing them in terms of cost, number of integrated actuators and sensors, main haptic feedback typology, and future applications. Finally, a survey of sensing systems that implement haptic feedback technologies, particularly smart gloves, is introduced by discussing their general key design requirements and technical features. A fundamental task that an HMI's transducer should accomplish is to gather and elaborate data coming from its sensing system through an efficient and well-designed signal conditioning section that improves the functionality of the same HMI's transducer.