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Textile Organic Electrochemical Transistors as a Platform for Wearable Biosensors

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ABSTRACT

The development of wearable chemical sensors is receiving a great deal of attention in view of non-invasive and continuous monitoring of physiological parameters in healthcare applications. This paper describes the development of a fully textile, wearable chemical sensor based on an organic electrochemical transistor (OECT) entirely made of conductive polymer (PEDOT:PSS). The active polymer patterns are deposited into the fabric by screen printing processes, thus allowing the device to actually “disappear” into it. We demonstrate the reliability of the proposed textile OECTs as a platform for developing chemical sensors capable to detect in real-time various redox active molecules (adrenaline, dopamine and ascorbic acid), by assessing their performance in two different experimental contexts: i) ideal operation conditions (i.e. totally dipped in an electrolyte solution); ii) real-life operation conditions (i.e. by sequentially adding few drops of electrolyte solution onto only one side of the textile sensor). The OECTs response has also been measured in artificial sweat, assessing how these sensors can be reliably used for the detection of biomarkers in body fluids. Finally, the very low operating potentials (<1 V) and absorbed power (~10−4 W) make the here described textile OECTs very appealing for portable and wearable applications.

No MeSH data available.


Response of a textile OECT in configuration G1.(A) Id vs. time curve (Vg = −0.9 V; Vd = −0.3 V) obtained after the addition of different adrenaline amounts. The additions are labeled with arrows indicating the increase of concentration. (B) 1 − I/Imax vs. LogCAA plot. (C) Working principle of textile OECTs.: the PEDOT:PSS channel exhibits a potential which is high enough to electro-oxidize adrenaline. The reaction is also reported in simplified form in the panel according to Coppedè et al.20. The oxidation leads to hole extraction from the transistor channel material and, thus, Id decreases.
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f4: Response of a textile OECT in configuration G1.(A) Id vs. time curve (Vg = −0.9 V; Vd = −0.3 V) obtained after the addition of different adrenaline amounts. The additions are labeled with arrows indicating the increase of concentration. (B) 1 − I/Imax vs. LogCAA plot. (C) Working principle of textile OECTs.: the PEDOT:PSS channel exhibits a potential which is high enough to electro-oxidize adrenaline. The reaction is also reported in simplified form in the panel according to Coppedè et al.20. The oxidation leads to hole extraction from the transistor channel material and, thus, Id decreases.

Mentions: The transistors were soaked in PBS solution under stirring (Fig. 2D), and the gate and the drain were biased at −0.9 V and −0.3 V, respectively. These values were optimized in a previous work31 for an all-PEDOT:PSS OECT sensor obtained on a glass slide substrate. Since oxidizable compounds are detected by OECTs through a decrease of the drain current, a highly conductive channel ensures a high sensitivity and a wide linear range because of the high starting Id obtained. The chosen gate voltage ensures a quick and stable response. Figure 4A shows the Idvs time plot that was recorded from a textile OECT in configuration G1 while different amounts of adrenaline were added in the electrochemical cell. Adrenaline, dopamine and ascorbic can be detected by the sensor because they are oxidizable compounds and, consequently, they react with the positively-biased PEDOT:PSS channel with an electro-catalytic pathway37. As a further evidence of the proposed mechanism, the electrochemical potential of the source collector was measured with respect to a Saturated Calomel Electrode before starting the analyte additions and resulted equal to 0.52 V. Consequently, the gate electrochemical potential was −0.38 V. These data point out that only the PEDOT:PSS located in the channel exhibits an electrochemical potential that is high enough (>Eox of analytes) to electro-catalyze the oxidation of the here examined biomolecules37 (Fig. SI7 for adrenaline). The reaction between adrenaline and PEDOT is reported (Fig. 4).


Textile Organic Electrochemical Transistors as a Platform for Wearable Biosensors
Response of a textile OECT in configuration G1.(A) Id vs. time curve (Vg = −0.9 V; Vd = −0.3 V) obtained after the addition of different adrenaline amounts. The additions are labeled with arrows indicating the increase of concentration. (B) 1 − I/Imax vs. LogCAA plot. (C) Working principle of textile OECTs.: the PEDOT:PSS channel exhibits a potential which is high enough to electro-oxidize adrenaline. The reaction is also reported in simplified form in the panel according to Coppedè et al.20. The oxidation leads to hole extraction from the transistor channel material and, thus, Id decreases.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5035988&req=5

f4: Response of a textile OECT in configuration G1.(A) Id vs. time curve (Vg = −0.9 V; Vd = −0.3 V) obtained after the addition of different adrenaline amounts. The additions are labeled with arrows indicating the increase of concentration. (B) 1 − I/Imax vs. LogCAA plot. (C) Working principle of textile OECTs.: the PEDOT:PSS channel exhibits a potential which is high enough to electro-oxidize adrenaline. The reaction is also reported in simplified form in the panel according to Coppedè et al.20. The oxidation leads to hole extraction from the transistor channel material and, thus, Id decreases.
Mentions: The transistors were soaked in PBS solution under stirring (Fig. 2D), and the gate and the drain were biased at −0.9 V and −0.3 V, respectively. These values were optimized in a previous work31 for an all-PEDOT:PSS OECT sensor obtained on a glass slide substrate. Since oxidizable compounds are detected by OECTs through a decrease of the drain current, a highly conductive channel ensures a high sensitivity and a wide linear range because of the high starting Id obtained. The chosen gate voltage ensures a quick and stable response. Figure 4A shows the Idvs time plot that was recorded from a textile OECT in configuration G1 while different amounts of adrenaline were added in the electrochemical cell. Adrenaline, dopamine and ascorbic can be detected by the sensor because they are oxidizable compounds and, consequently, they react with the positively-biased PEDOT:PSS channel with an electro-catalytic pathway37. As a further evidence of the proposed mechanism, the electrochemical potential of the source collector was measured with respect to a Saturated Calomel Electrode before starting the analyte additions and resulted equal to 0.52 V. Consequently, the gate electrochemical potential was −0.38 V. These data point out that only the PEDOT:PSS located in the channel exhibits an electrochemical potential that is high enough (>Eox of analytes) to electro-catalyze the oxidation of the here examined biomolecules37 (Fig. SI7 for adrenaline). The reaction between adrenaline and PEDOT is reported (Fig. 4).

View Article: PubMed Central - PubMed

ABSTRACT

The development of wearable chemical sensors is receiving a great deal of attention in view of non-invasive and continuous monitoring of physiological parameters in healthcare applications. This paper describes the development of a fully textile, wearable chemical sensor based on an organic electrochemical transistor (OECT) entirely made of conductive polymer (PEDOT:PSS). The active polymer patterns are deposited into the fabric by screen printing processes, thus allowing the device to actually “disappear” into it. We demonstrate the reliability of the proposed textile OECTs as a platform for developing chemical sensors capable to detect in real-time various redox active molecules (adrenaline, dopamine and ascorbic acid), by assessing their performance in two different experimental contexts: i) ideal operation conditions (i.e. totally dipped in an electrolyte solution); ii) real-life operation conditions (i.e. by sequentially adding few drops of electrolyte solution onto only one side of the textile sensor). The OECTs response has also been measured in artificial sweat, assessing how these sensors can be reliably used for the detection of biomarkers in body fluids. Finally, the very low operating potentials (<1 V) and absorbed power (~10−4 W) make the here described textile OECTs very appealing for portable and wearable applications.

No MeSH data available.