Switchable Hydrogel-Gated Organic Field-Effect Transistors

Abstract

Stimuli-responsive hydrogels represent a class of materials capable of reversibly switching their morphological and physicochemical characteristics. An ultrathin poly(acrylic acid) film (ca. 6 nm) grafted onto the gate of a p-type EGOFET is studied, and the correlation between the swelling state of the hydrogel and the transistor output characteristics is presented. The hydrogel-related swelling process occurring in basic medium causes an increase in threshold voltage due to the abrupt and intense increase of the negative charge density on the gate electrode. The variation of the drain current during the in situ modification of the pH electrolyte allows a quantitative analysis of the hydrogel switching kinetics. This work shows not only the relevance of EGOFET as an analytical tool in the broad sense, i.e., able to follow in real time phase transition processes of stimuli-responsive materials, but also the relevance of using a hydrogel for field-effect-based (bio)detection according to the ability of such material to overcome the well-known Debye length problematics.

Transistors for Chemical Monitoring of Living Cells

“…By properly functionalizing the gate electrode with specific molecules (e.g., antibodies), the target molecules present inside the electrolyte interact with the gate surface, leading to modification of the interface capacitance which, in turn, modulates the drain current, even for an uncharged target at trace levels [ 91 ]. Their pertinence has been demonstrated for pH sensing [ 92 , 93 ] and biosensing for the detection of small toxic organic molecules [ 91 , 94 ] or proteins secreted by cells (e.g., interleukins [ 95 , 96 ] and TNF-α (tumor necrosis factor alpha) [ 97 ]). The fact that EGOFETs have not yet been used for living cells’ monitoring could be due to the fact that these EGOFETs have always been reported using top-gate configurations, and never using side-gates.…”

Artificial Indium‐Tin‐Oxide Synaptic Transistor by Inkjet Printing Using Solution‐Processed ZrOx Gate Dielectric

“…However, most of the reported synaptic transistors with EDL layers are organic materials, but organic materials show poor device stability and lifetime. [ 20–23 ] The metal‐oxide gate dielectric is an alternative way to achieve excellent device stability in environmental and electrical properties.…”

Perspectives in the design and application of composites based on graphene derivatives and bio‐based polymers

“…For example, rGO/polymer composite electrodes showed pH-, temperature-and ion-sensitive dynamic behavior during redox reactions. [25][26][27] Here we aim to show the perspectives of graphene derivatives and bio-based polymers for the design of new functional composites. Moreover, perspectives in the developments of diverse application fields, including efficient self-adaptive programmable membranes, energy-related and bionic devices, are highlighted.…”

“…Some composite materials even have biomimetic properties such as self‐healing, self‐adaptation and stimuli‐responsive behavior. For example, rGO/polymer composite electrodes showed pH‐, temperature‐ and ion‐sensitive dynamic behavior during redox reactions 25–27 . Here we aim to show the perspectives of graphene derivatives and bio‐based polymers for the design of new functional composites.…”