Specially Designed Polyaniline/Polypyrrole Ink for a Fully Printed Highly Sensitive pH Microsensor

Abstract

pH sensing for healthcare applications requires sensors with mechanically stable materials of high sensitivity and high reproducibility combined with low-cost fabrication technologies. This work proposes a fully printed pH sensor based on a specially formulated conducting polymer deposited on a microelectrode in a flexible substrate. A formulation, which combined polyaniline (PANI) and polypyrrole (PPy) with integrated polyelectrolyte poly(sodium 4-styrenesulfonate) (PSS), was specially prepared to be printed by inkjet printing (IJP). The sensor has good sensitivity in the physiological region (pH 7–7.5) key for the healthcare biosensor. This mixture printed over a commercial gold ink, which has a singular chemical functionalization with phthalocyanine (Pc), increased the sensor sensitivity, showing an excellent reproducibility with a linear super-Nernstian response (81.2 ± 0.5 mV/pH unit) in a wide pH range (pH 3–10). This new ink together with the IJP low-cost technique opens new opportunities for pH sensing in the healthcare field with a single device, which is disposable, highly sensitive, and stable in the whole pH range.

Superhydrophobic Functionalized Ti3C2Tx MXene-Based Skin-Attachable and Wearable Electrochemical pH Sensor for Real-Time Sweat Detection

“…Among the components of sweat pH sensors, the sensitivity and responsiveness of the flexible solid-contact ISEs fabricated through screen printing, spray-coating, drop-casting, and magnetron sputtering deposition techniques determine the performance of the wearable devices for ion sensing. − The critical issues are the potential stability, the hydrophobicity of the transducing layer material (interfacial aqueous layer effect), and the interfacial redox/double-layer capacitance between the transducer and the ion-selective membrane (ISM). , A series of solid-contact functional materials are used as ion-to-electron transducing layer materials including conductive polymers, carbon-based materials, metal nanomaterials, and semiconducting metal oxides . Polyaniline (PANI) is a common conductive polymer with low cytotoxicity and is extensively used as a pH-sensitive material for detecting hydronium ions (H 3 O + ) through surface deprotonation. − Carbon-based materials such as graphene and carbon nanotubes have been widely applied to pH sensor applications due to their structural controllability, high sensitivity, biocompatibility, and electrical characteristics. − Gan et al through electrochemical lattice H + intercalation obtained WO 3 -based pH sensors with tunable sensitivity and selectivity . However, the continuous development of the high specific surface area and high capacitance nanomaterials used as solid-contact layers for pH sensors is essential.…”

“…16 Polyaniline (PANI) is a common conductive polymer with low cytotoxicity and is extensively used as a pH-sensitive material for detecting hydronium ions (H 3 O + ) through surface deprotonation. 17 materials such as graphene and carbon nanotubes have been widely applied to pH sensor applications due to their structural controllability, high sensitivity, biocompatibility, and electrical characteristics. 20−22 Gan et al through electrochemical lattice H + intercalation obtained WO 3 -based pH sensors with tunable sensitivity and selectivity.…”

Integration of nanomaterial sensing layers on printable organic field effect transistors for highly sensitive and stable biochemical signal conversion

“…Zea et al also fabricated a flexible pH microsensor based on a mixed conductive polymer of PANI and PPy using inkjet printing (IJP) technology. 89 In a wide pH range (pH 3–10), the fully printed pH electrode showed a high sensitivity (81.2 mV per pH) and excellent reproducibility. Hryniewicz et al reported an impedimetric immunosensor for SARS-CoV-2 nucleocapsid protein monoclonal antibody detection by PPy–AuNP modified electrodes.…”

Highly Sensitive Silver‐Microlayer Thin Film on a pp‐PFM‐Modified PDMS Strain Sensor as a Versatile Tool for Stretchable Electronics Applications

“…Electrical Properties: The electrical properties of the strain sensors were evaluated using the same set-up previously used in our work. [51,52] Briefly, strain sensors were connected to four-point probe station (Figures S2 and S3, Supporting Information) that was connected to a source meter Keithley 2600. The sourcemeter was also connected to a PC for the obtention of the real-time data.…”