stimulation or probing of biological events. The most successful example of stable and

efficient bioelectronic material is poly(3,4-ethylenedioxythiophene) polystyrene sulfonate

(PEDOT:PSS), which is widely used in bioelectronics due to its stability under biological

conditions, as well as its commercial availability, and excellent mixed ionic and electronic

conduction properties [2]. The most important advantages and disadvantages of organic

and inorganic materials are summarized in Table 4.1.

4.3 Conjugated Polymers

Conjugated polymers (CPs) are the workhorse materials for organic bioelectronics. For

this reason, there are a wealth of studies in which these systems are employed as bioe­

lectronic transducers. Thus, we do not aim at giving a detailed list of reports on CPs for

TABLE 4.1

Summary of Advantages and Disadvantages of the Material Groups Used in Bioelectronics

Advantages

Disadvantages

Metals

• Good stability

• Established processing and

functionalization methods

• Easy fabrication of nanostructures

(i.e. colloidal nanoparticles)

• High crystallinity

• Low toxicity in many cases

• High electrical stability

• Mechanical mismatch at the

biotic interface

• Electronic mismatch at the

biotic interface

• High stiffness

• Low conformability

Inorganic

semiconductors

• Good stability

• Established processing

• High crystallinity in most cases

• Easy fabrication of nanostructures

(i.e. colloidal nanoparticles)

• Tunable optoelectronic properties

(doping)

• Easy surface functionalization

• Mechanical mismatch at the

biotic interface

• Electronic mismatch at the

biotic interface

• Presence of the oxide layer at

the surface

• High stiffness

• Low conformability

• Cytotoxicity in many cases

Organic

semiconductors

• High affinity with biological

matter and biocompatibility

• Low temperature solution process

• Large variety of structures and

morphologies

• Tunable optoelectronic and

mechanical properties

• Conformable and stretchable

materials

• Ionic and electronic conduction

• Oxide-free materials

• Low stability in air and in

biological settings

• Low crystallinity

• Low charge carrier mobility

Materials for Organic Bioelectronics

57