Flexible Organic Transistors for Biosensing: Devices and Applications

Abstract

Flexible and stretchable biosensors can offer seamless and conformable biological–electronic interfaces for continuously acquiring high‐fidelity signals, permitting numerous emerging applications. Organic thin film transistors (OTFTs) are ideal transducers for flexible and stretchable biosensing due to their soft nature, inherent amplification function, biocompatibility, ease of functionalization, low cost, and device diversity. In consideration of the rapid advances in flexible‐OTFT‐based biosensors and their broad applications, herein, a timely and comprehensive review is provided. It starts with a detailed introduction to the features of various OTFTs including organic field‐effect transistors and organic electrochemical transistors, and the functionalization strategies for biosensing, with a highlight on the seminal work and up‐to‐date achievements. Then, the applications of flexible‐OTFT‐based biosensors in wearable, implantable, and portable electronics, as well as neuromorphic biointerfaces are detailed. Subsequently, special attention is paid to emerging stretchable organic transistors including planar and fibrous devices. The routes to impart stretchability, including structural engineering and material engineering, are discussed, and the implementations of stretchable organic transistors in e‐skin and smart textiles are included. Finally, the remaining challenges and the future opportunities in this field are summarized.

Remarkable Enhancement of Hole Mobility of Novel DA‐D’‐AD Small Molecules by Thermal Annealing: Effect of the D’‐Bridge Block.

“…The Stille reaction between compound 4 (1 eq.) and 4,7dibromobenzo[c] [1,2,5]thiadiazole resulted in compound 5 with the yield of 50 %.…”

“…In particular, OSMs such as conjugated polymers or low molecular compounds (small molecules) can be processed from solution by different coating techniques on lightweight, mechanically flexible substrates or even on stretchable textiles. [2,3] Therefore, easy processing along with modulation of properties of OSMs by molecular design allows to fabricate various electronic devices such as organic solar cells, [4] organic photodetectors, [5,6] and organic field-effect transistors [7] with desired functions. In the last decade, organic semiconductors with conjugated backbone structure have also found application in perovskite solar cells as dopant-free holeor electron-transport materials.…”

Interfacial Polymer Engineered Field Effect Transistor Biosensors for Rapid and Efficient Identification of SARS‐CoV‐2 N Antigen

“…Field‐effect transistor (FET) biosensors with intrinsic signal amplification capability could directly convert trace biomolecule information into a readable electrical signal, endowing its high sensitivity characteristic. [ 20−23 ] Particularly, the response time of FET biosensors for target detection reaches as low as a few seconds and the dimension of FET biosensors could be miniatured to a portable format, promising the potential of FET biosensors in real‐time and point‐of‐care N antigen monitoring. [ 24‐26 ] The sensing principle of FET biosensors relies on the change in charge carriers at the biosensing interface upon the recognition of charged target biomolecules.…”

3D-Printed Intrinsically Stretchable Organic Electrochemical Synaptic Transistor Array

“…Skin-like bioelectronics have gained wide application in health detection, human–computer interaction, and biological research due to their ability to seamlessly adhere in vitro or in vivo for detecting and amplifying biological signals without causing discomfort to organisms. − As a key component of bioelectronics, organic electrochemical transistors (OECTs) are devices that utilize electrochemical doping to control the conductivity of organic mixed ionic–electronic conductors to achieve switching states, which can be used as signal modulators and electronic components. , Additionally, organic electrochemical transistors with high transconductance, low operating voltage (<1 V), intrinsic stretchability, and low-cost processing technology have important research significance for developing bioelectronics. ,, Nevertheless, there are some difficulties in fabricating intrinsically stretchable (is-) OECT using a simple and versatile processing method. For example, all the components of the is-OECT, including electrodes, semiconducting layers, and dielectric layers, need to be stretchable and fabricated layer by layer. , The versatility of 3D printing enables the easy creation of highly customized and complex objects, making it a valuable tool for preparing OECTs.…”