###### Abstract
For example, DW is an additive manufacturing (AM) method that directly transfers onto a substrate material, also called digital writing or digital printing, while DIW, called the direct-write assembly, is an extrusion-based 3D AM printing method in which liquid or semisolid colloidal inks are dispensed via small nozzles under controlled pressure and flow rates. These methods are fabrication methods that are used to produce micro devices, printed circuit board (PCB) electronics, optics biosensing devices including biocompatible scaffolds for tissue engineering, and high-performance energy storage systems [27; 28]. In [29], the research investigated a liquid-based eutectic gallium-indium (EGaIn) to design sensing devices in WBAN. Intelligent sensing based on commercial Wi-Fi devices is an emerging technology for next-generation healthcare monitoring with great potential for future development due to its low cost and availability. However, an integration of TENG technology presents a promising solution for wearable health devices and disease diagnostics, as it allows for real-time, portable monitoring without the need for external power sources. Key characteristics of the sensors created in this manner include their biocompatibility, scalability, lightweight design, flexibility, and wearability. Additionally, connection with a triboelectric source has made it possible to develop a self-powered, wearable, portable sensor. Smart sensors are useful because they can be created rapidly and affordably, worn conveniently, have a long lifespan, react swiftly,and may be used anywhere and at any time. They are also resistant to water and other factors [30, 31]. However, this manuscript aims to address these gaps by considering the following key requirements:  
1. Exploration of the latest developments in flexible, rigid, liquid, and next-generation devices. 2. Examination of advanced DIW and DW fabrication methods. 3. Integration of body phantom models to account for the impacts of the human body and development of more accurate and realistic human body phantom models. By incorporating these requirements, this review paper offers a unique view that simultaneously considers three dynamic developments that have not been extensively studied together. Many researchers are currently involved in solving all these challenges. For example, several different types of wearable and flexible sensor devices have already been discussed and have shown a very reasonable performance in WBAN systems such as flexible and stretchable, self-powered and degradable humidity sensors, biofluidic, Mxene ink, liquid, and next-generation miniaturised wearable and flexible sensor devices [8, 13, 15, 17]. State-of-the-art reviews based on advancements in DW- and DIW-based and emerging fabricated systems such as 3D to 6D have also been studied [27, 28]. The human body methods such as on-body body phantom models for evaluation have already been drawn with the aim to provide researchers with a holistic understanding of devices and their impact on complex human body situations and provide advancements in design and manufacturing methods. Therefore, the development of realistic simulation and emulation platforms is essential for evaluating these techniques in their initial phase of development. In recent years, the research community has shown a keen interest in the development of more accurate and realistic phantoms for different sensing techniques based on microwaves, magnetic resonance imaging (MRI), optics, and acoustic optics [11, 12, 13, 30]. Given this, it is fruitful to retrospectively examine the recent progress in the field of wearable and flexible sensor devices, including their design, fabrication, and on-body applications in WBAN systems. This manuscript is arranged as follows: It begins with an introduction, followed by Section 2, which describes wearable and wireless communication devices. Section 3 provides the latest comprehensive overview of DIW and DW fabrication techniques for wearable devices, featuring examples and detailed descriptions.