**1. Introduction**

Green electronics represents an occurring area of research aimed at identifying compounds of natural origin and establishing cost-reasonable ways for the synthetic materials that have utility in environmentally safe and/or biocompatible devices. There are several biocompatible sensing technologies that can perform innumerable physical and physiological measurements. Apart from carbon-based nanomaterials, other active sensing components are widely reported. These materials include polymers, semiconductors and metallic conductor-based nanomaterials as well as ionic and metallic liquids.

Carbon-based technologies are meant to address the energy and cost inefficiency issues posed by their inorganic counterparts. Organic electronics (based on i.e. conjugated polymers, CPs)

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

entered the research field in the 1970s holding the high promise of delivering cost-reasonable and energy-efficient materials and devices. Despite intense effort of the scientific community during the past 30 years, the efficiency and stability of organic semiconductors endure at current times' major obstacles in their development as solid challengers of the inorganic materials [1–3]. Consequently, the large-scale rapid replacement of hard core inorganic counterparts, like the ones active in high-speed processors, integrated circuits, and solar cell modules, with organic components is not immediately expected [1–3]. However, the "soft" nature of carbonbased components confers them a serious benefit over the inorganic materials, enabling production of flexible, conformable and even extremely thin electronic equipment [4].

Conducting polymers, the so-called "fourth generation of polymeric materials", can provide effective methods for the diagnosis and treatment of different disorders, that is, diabetes. Conducting polymers have often excellent biocompatibility. They can provide favorable interfaces for bioelectrodes owing to their hybrid conducting processes, combining both electron and ionic charge carriers. Many (i.e. glucose) biosensors use immobilized enzymes to construct a selective layer on CP structure. Miniaturization of sensors is a new demand. Mini sensors are portable and wearable with low utilization of sample. New biosensors with a market size of a US\$13 billion annual turnover have quickly become valuable instruments in the healthcare. Actually, glucose biosensors (accounting for 85% of the total biosensor market) have notably mended the quality of life of diabetics [5].

its poor solubility and processability, PEDOT is often mixed with PSS to generate water soluble poly(3,4-ethylenedioxythiophene):poly(styrene sulphonate)—PEDOT:PSS, which was developed and patented in 1988 by Bayer AG [15]. Doping of PSS could disrupt the combination of the PEDOT chains and lower their electrochemical efficiency [16]. Despite the fact that water soluble PEDOT:PSS can be applied to generate conducting thin films, the resulting planar layer lacks morphological benefit, having only restricted accessible surface in comparison with processable

Conducting Polymers as Elements of Miniature Biocompatible Sensor

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To date, some electrical conductors have been applied in implantable biological interfaces such as cardiac patches [17], neural interfaces [18], electroceuticals [19] and on-command drug delivery platforms [20]. Although classic inorganic electrical materials (i.e. metals and semiconductors) are not appropriate for a seamless biointerface because of the need for extracellular functionalities, the semiconducting polymers seem to be valuable alternatives for these applications [21]. Controlling this limited biocompatibility in flexible electronic materials endures a challenge, and is recently drawing fair research efforts in the bioelectronics group.

**Conducting polymer Maximum conductivity (S/CM) Type of doping**

Polyacetylene (PA) 200–1000 n, p Polyparaphenylene (PPP) 500 n,p Polyaniline (PANI) 5 n, p Polyparavinylene (PPV) 1–1000 p Polyparaphenylene sulphide (PPS) 3–300 p Polypyrrole (PPY) 40–200 p Polythiophene (PT) 10–100 p PEDOT:PSS 100–1500 p

colloidal interface materials [16].

**Figure 1.** The most common CPs as sensor elements.

**Table 1.** The conductivity of the most common CPs.
