Table 9.

Benefits and challenges related to 3D-printing of the nano MEH systems

Benefits	The accurate pattern-making ability for architectural customization of the nanogenerators. The tiny-structured patterns allow easy implementation and mechanical resilience to electronics
	Lower power consumption and environmental impact. Facilitates long-term sustained production
	Provides faster speed and high-fabrication compatibility
	Less human intervention is required in the printing of the parts and post-treatment
	Abatement of waste materials and overall material usage
	3D printing is a safe, sensitive, and flexible fabrication facility
	Excellent chemical attributes characterize the printed objects
	FDM printing gives heat resistance and good mechanical strength to the prototypes
	Facilitates easy and manual removal of the supporting elements, i.e., water-soluble wax at the end of the printing process
	Fast solidification of the printed components on various substrates
	Exceptional printing accuracy and resolution
Limitations	The complex integration of functional polymers
	To achieve and maintain the tiny gap required between triboelectric polymer surfaces is challenging
	The formation of precise macro/nano dimensional architectures is yet to be studied
	The combination of various materials for 3D printed TENGs is problematic
	The development of integrated systems comprising of nanogenerators and functional devices and simultaneous handling of multiple printing materials is still challenging
	3D printed nano MEH systems are needed to be biocompatible and integrated with biological tissues
	End-of-life recyclability/biodegradability of the 3D-printed components is a critical concern to reduce impacts on the environment and the human body
	For complex models, the printing time is often high
	Digital light processing (DLP) demands more light sources, for instance, arc lamps during printing
	A liquid crystal display is employed at the entire 3D-printed deposit during a single layer of the DLP
	In 3D printing of fabrics, it is challenging to develop appropriate CAD modeling in order to facilitate the simulation of the draping of the textile across a curved surface
	3D-printed textiles are not strong enough and tend to break easily due to the conventional textiles' lesser flexibility. Hence, they are not very suitable for day to day textile applications

The references of the research papers cited in this table are provided in the Additional file 1