PEDOT: Dye-Based, Flexible Organic Electrochemical Transistor for Highly Sensitive pH Monitoring

Abstract

Organic electrochemical transistors (OECTs) are bioelectronic devices able to bridge electronic and biological domains with especially high amplification and configurational versatility and thus stand out as promising platforms for healthcare applications and portable sensing technologies. Here, we have optimized the synthesis of two pH-sensitive composites of PEDOT (poly(3,4-ethylenedioxythiophene)) doped with pH dyes (BTB and MO, i.e., Bromothymol Blue and Methyl Orange, respectively), showing their ability to successfully convert the pH into an electrical signal. The PEDOT:BTB composite, which exhibited the best performance, was used as the gate electrode to develop an OECT sensor for pH monitoring that can reliably operate in a two-fold transduction mode with super-Nernstian sensitivity. When the OECT transconductance is employed as analytical signal, a sensitivity of 93 ± 8 mV pH unit is achieved by successive sampling in aqueous electrolytes. When the detection is carried out by dynamically changing the pH of the same medium, the offset gate voltage of the OECT shifts by (1.1 ± 0.3) × 10 mV pH unit. As a further step, the optimized configuration was realized on a PET substrate, and the performance of the resulting flexible OECT was assessed in artificial sweat within a medically relevant pH range.

Semiconducting Small Molecules as Active Materials for p‐Type Accumulation Mode Organic Electrochemical Transistors

“…Organic electrochemical transistors (OECTs), as depicted schematically in Figure , have been widely explored for interfacing organic electronics with biologically and medically relevant systems. [ 1,2 ] The burgeoning field of organic bioelectronics has seen OECTs employed in a wide range of applications from neural interface devices for epileptogenic centers, [ 3 ] to biological analyte detection, [ 4–7 ] cardiac monitoring, [ 8 ] whole cell interface monitoring, [ 9,10 ] pH sensing, [ 11 ] in ion pumps, [ 12 ] and electronic plants. [ 13 ] While OECTs traditionally have comprised the conducting polymer mixture poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), semiconducting polymers have more recently been implemented as the active material in OECTs.…”

Real‐Time Monitoring of Glucose Export from Isolated Chloroplasts Using an Organic Electrochemical Transistor

“…measurement of pH, detection of ions, metabolites, and neurotransmitters. [15][16][17][18][19][20][21][22] Major efforts have been focused on the development of glucose sensors as glucose is one of the most important metabolites and is a crucial parameter and indicator for several diseases. A few demonstrations have been reported where glucose is monitored from natural samples such as sweat, [21] saliva, [20] or cell media.…”

Ultimately Sensitive Organic Bioelectronic Transistor Sensors by Materials and Device Structure Design

“…A great deal of published papers on organic FET biosensors are based on the OECT configuration and among those, the large majority is engaged with the detection of redox species such as, for instance, glucose, gallic acid, dopamine, and uric acid . Another quite ample section of OECTs are engaged for selective ion detection . In this respect, they can be considered complementary to the EGOFETs that usually sense species that are not electroactive by using ion‐impermeable electronic channel materials.…”