# Additively Manufactured Polymers for Electronic Components
## 3 Polymers Used for AM in Electronic Applications  
### Intrinsically Conductive Polymers (ICPs)  
Although ICPs exhibit lower mobility and conductivity when compared to their inorganic counterparts, like silicon and copper, they have emerged as significant contenders in the electronics and optoelectronics industries. This is primarily due to the possibility of tuning their properties according to specific application needs and to the ease of processing them as a solution. These characteristics, along with their cost effectiveness and suitability for near-room temperature solution processing, make ICPs attractive for consumer electronics [44]. Furthermore, CPs possess unique chemical, physical, and processing properties that position them as competitive candidates for the next generation of wearable or implantable electronics. These applications demand stretchable electronic devices, accommodating the three-dimensional movements of the human body while preserving their electrical performance. Many of the solution processing techniques developed for CPs in applications such as organic photovoltaics (OPV), OLEDs, or organic field-effect transistors (OFETs) can be adapted for the fabrication of wearable and epidermal organic electronics [28]. ICPs are composed of unsaturated building blocks, including arenes, olefins, or acetylenes, which are linked by single bonds that possess some \(\pi\)-bond character. This arrangement results in the formation of extensive domains containing delocalised and polarisable \(\pi\)-electrons. Some classical examples of ICPs include polyacetylene, poly(p-phenylene), poly(p-phenylene vinylene), poly(p-phenylene ethynylene), and polyfluorene. The potential for synthesising a wide range of diverse conjugated polymers is evident. This can be achieved by altering the aromatic repeat unit, such as substituting larger polycyclic aromatic hydrocarbons for the benzene ring, or by modifying the position of the substitutes on the aromatic rings, as exemplified by poly(m-phenylene) and poly(o-phenylene). Moreover, the incorporation of heteroatoms into the aromatic ring opens avenues for even more complex conducting polymers, including polythiophene, polypyrrole, polycarbazole, or the addition of a functional group to the backbone of the polymer, as seen in polyaniline, as shown in Figure 2[44,45]. Among all of the conjugated polymers, the most used and investigated is poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS), represented in Figure 3. It is widely recognised as the most remarkable conducting polymer due to its adjustable conductivity, high transparency, excellent film-forming properties, and good thermal stability [46]. Recently, there have been notable advancements in DIW of PEDOT:PSS [46,47]. This innovative and versatile PEDOT:PSS processing method enables precise control over the diameter and arrangement of printed strands in a localised and highly efficient manner. As a result, it offers significant potential for developing microelectronic array devices. PEDOT:PSS pillars with varying aspect ratios have been successfully created by adjusting various printing parameters, such as pulling speed, pulling time, polymer solution concentration, and tip diameter. This includes the production of high-aspect-ratio pillars measuring 7 \(\upmu\)m in diameter and 5000 \(\upmu\)m in height [48]. Wearable electronic devices have also been developed by combining PEDOT with another semi-conductive polymer,poly(3-hexyl thiophene) (P3 HT). In the study conducted by [PERSON] et al., the PEDOT:PSS layer, approximately 300 nm thick, exhibited a low sheet resistance of around 70 \(\Omega\) sq\({}^{-1}\)[49].