Organic thin film transistors (OTFTs)-based biosensors are widely applied as advanced biosensing platforms by virtue of their inherent ability to transfer and amplify received biological signals into electrical signals. Nevertheless, the development of OTFTs-based biosensors with excellent sensitivity, selectivity, and stability for specific biological processes remains a major challenge. This mini review focuses on recent achievements in OTFTs-based biosensors since 2010. Specifically, three types of OTFTs, specifically organic field-effect transistors (OFETs), electrolyte-gated OFETs (EGOFETs), and organic electrochemical transistors (OECTs) are summarized in terms of the key strategies required for highperformance bioelectronics. Additionally, various OTFTs-based biosensors, such as ions, glucose, nucleic acids, proteins, and cells are described in terms of their working principles. This mini review highlights the uses of OTFTs for a broad range of research applications with a focus on designing novel OTFTs-based biosensors.

Organic field-effect transistors (OFETs) are considered as one of the cost-effective biosensor devices with rapid detection capabilities and multiparameter responses. However, the functionalization processes on normal organic devices might impact the device performance for its further sensitive and reliable sensing applications. Herein, we develop a novel organic material, 2,6-bis­(4-formylphenyl)­anthracene (BFPA) for use as the protective and functional layer of OFET-based biosensors, enabling ultrasensitive determination of alpha-fetoprotein (AFP) with femtomolar accuracy in human serum. By monitoring changes of the source–drain current (I ds) and threshold voltage (V th) electrical signals, the device exhibits improved reliability in detecting AFP biomarkers and is able to differentiate between liver cancer patients and healthy individuals. Featuring label-free determination, shorter analysis time, and lower sample volume, this ultrasensitive and reliable OFET-based biosensor displays numerous advantages over traditional strategies such as enzyme-linked immunosorbent assay and electrochemiluminescence immunoassay, demonstrating that the proposed OFET-based biosensors have broader analytical and clinical applications for early liver cancer diagnosis.

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In recent years, organic field-effect transistors (OFETs) have shown great potential for advanced protein biochips due to their inherent biocompatibility and high-throughput detectability. However, the development of OFET-based protein biochips is still at an early stage. On the one hand, single-biomarker determination is not sufficient for the diagnosis of cancer; thus, simultaneous monitoring of electrical signals toward multi-biomarkers is widely concerned and explored. On the other hand, an optimized functionalization strategy for efficient protein immobilization is another key to make OFET-based protein biochips accessible with improved detection performance. Herein, a facile functionalization strategy is developed for excellent charge-transport thin films by suppressing the gelation of diketopyrrolopyrrole (DPP)-based polymer semiconductors with the addition of the glutaraldehyde cross-linking agent. Besides, functional groups are introduced on the device surface for efficient attachment of antibodies as receptors via a condensation reaction, enabling simultaneous determination of α-fetoprotein biomarker and carcinoembryonic antigen biomarker with improved sensitivity and reliability. Therefore, the proposed high-throughput OFET-based protein biochip has the potential to be widely utilized in early liver cancer diagnosis.

Nowadays, most manufacturing memory devices are based on materials with electrical bistability (i. e., “0” and “1”) in response to an applied electric field. Memory devices with multilevel states are highly desired so as to produce high‐density and efficient memory devices. Herein, we report the first multichannel strategy to realize a ternary‐state memristor. We make use of the intrinsic sub‐nanometer channel of pillar[5]arene and nanometer channel of a two‐dimensional imine polymer to construct an active layer with multilevel channels for ternary memory devices. Low threshold voltage, long retention time, clearly distinguishable resistance states, high ON/OFF ratio (OFF/ON1/ON2=1 : 10 : 103), and high ternary yield (75 %) were obtained. In addition, the flexible memory device based on 2DPTPAZ+TAPB can maintain its stable ternary memory performance after being bent 500 times. The device also exhibits excellent thermal stability and can tolerate a temperature as high as 300 °C. It is envisioned that the results of this work will open up possibilities for multistate, flexible resistive memories with good thermal stability and low energy consumption, and broaden the application of pillar[n]arene.