Query: Organic field-effect transistor-based flexible sensors

Candidate papers:

abstract: Flexible electronic devices have attracted a great deal of attention in recent years due to their flexibility, reduced complexity and lightweight. Such devices can conformably attach themselves to any bendable surface and can possess diverse transduction mechanisms. Consequently, with continued emphasis on innovation and development, major technological breakthroughs have been achieved in this area. This review focuses on the advancements of using organic field effect transistors (OFETs) in flexible electronic applications in the past 10 years. In addition, to the above mentioned features, OFETs have multiple advantages such as low cost, readout integration, large area coverage, and power efficiency, which yield synergy. To begin with, we have introduced organic semiconductors (OSCs) followed by their applications in various device configurations and their mechanisms. Later, the use of OFETs in flexible sensor applications is detailed with multiple examples. Special attention is paid to discussing the effects induced on physical parameters of OFETs with respect to variations in external stimuli. The final section provides an outlook on the mechanical aspects of OSCs, activation and revival processes of sensory layers, small area analysis, and pattern recognition techniques for electronic devices.
author_names: Saravanan Yuvaraja

Ali Nawaz

Qian Liu

Deepak P Dubal

Sandeep Goud Surya

Khaled Nabil Salama

Prashant Sonar
title: Organic field effect transistor based flexible sensors.
venue: Chemical Society reviews
year: 2020

abstract: Organic field effect transistors (OFETs) with hexagonal barium titanate nanocrystals (h BTNCs) in amorphous matrix as one of the bilayer dielectric systems have been fabricated on a highly flexible 10 mm thick poly(ethylene terephthalate) substrate. The device current and mobility remain constant up to a bending radius of 4 mm, which makes the substrate suitable for wearable e skin applications. h BTNC films are found to be highly temperature sensitive, and the OFETs designed based on this material showed ultraprecision measurement ~4.3 mK) low power ~1 mW at 1.2 V operating voltage) and ultrafast response ~24 ms) in sensing temperature over a range of 20 45 degC continuously. The sensors are highly stable around body temperature and work at various extreme conditions, such as under water and in solutions of different pH values and various salt concentrations. These properties make this sensor unique and highly suitable for various healthcare and other applications, wherein a small variation of temperature around this temperature range is required to be measured at an ultrahigh speed.
author_names: Suman Mandal

Madhuchanda Banerjee

Satyajit Roy

Ajoy Mandal

Arnab Ghosh

Biswarup Satpati

Dipak K Goswami
title: Organic Field Effect Transistor Based Ultrafast, Flexible, Physiological Temperature Sensors with Hexagonal Barium Titanate Nanocrystals in Amorphous Matrix as Sensing Material.
venue: ACS applied materials interfaces
year: 2019

abstract: Organic Field Effect Transistors (OFETs) are attracting a rising interest for the development of novel kinds of sensing platforms. In this paper, we report about a peculiar sensor device structure, namely Organic Charge Modulated Field Effect Transistor (OCMFET) capable of operating at low voltages and entirely fabricated with large area techniques, i.e. inkjet printing and chemical vapor deposition, that can be easily upscaled to an industrial size. Device fabrication is described, and statistical characterization of the basic electronic parameters is reported. As an effective benchmark for the application of large area fabricated OCMFET to the biomedical field, its combination with pyroelectric materials and compressible capacitors is discussed, in order to employ the proposed device as a temperature pressure sensor. The obtained sensors are capable to operate in conditions which are relevant in the biomedical field (temperature in the range of 18.5 50 degC, pressure in the range of 102 103 Pa) with reproducible and valuable performances, opening the way for the fabrication of low cost, flexible sensing platforms.
author_names: Stefano Lai

Fabrizio Antonio Viola

Piero Cosseddu

Annalisa Bonfiglio
title: Floating Gate, Organic Field Effect Transistor Based Sensors towards Biomedical Applications Fabricated with Large Area Processes over Flexible Substrates
venue: Sensors
year: 2018

abstract: A novel flexible lactate sensor based on organic field effect transistors (OFETs) is demonstrated. Because lactate is known as a biomarker for assessing our physical performance, wearable lactate sensors could contribute to the monitoring of human health conditions. The flexible and low voltage operatable OFET possesses an extended gate modified with enzymes and an osmium redox polymer for the lactate detection, meaning that the continuous measurement of lactate levels (0 10 mM) has been successfully achieved. We believe that insight obtained will open up opportunities for applying OFETs in wearable biosensors.
author_names: Tsukuru Minamiki

Shizuo Tokito

Tsuyoshi Minami
title: Fabrication of a Flexible Biosensor Based on an Organic Field effect Transistor for Lactate Detection.
venue: Analytical sciences the international journal of the Japan Society for Analytical Chemistry
year: 2019

abstract: In this study, a novel approach to the fabrication of a multimodal temperature and force sensor on ultrathin, conformable and flexible substrates is presented. This process involves coupling a charge modulated organic field effect transistor (OCMFET) with a pyro/piezoelectric element, namely a commercial film of poly vinylene difluoride (PVDF) The proposed device is able to respond to both pressure stimuli and temperature variations, demonstrating the feasibility of the approach for the development of low cost, highly sensitive and conformable multimodal sensors. The overall thickness of the device is 1.2 mm, being thus able to conform to any surface (including the human body) while keeping its electrical performance. Furthermore, it is possible to discriminate between simultaneously applied temperature and pressure stimuli by coupling sensing surfaces made of poled and unpoled spin coated PVDF trifluoroethylene (PVDF TrFE, a PVDF copolymer) with OCMFETs. This demonstrates the possibility of creating multimodal sensors that can be employed for applications in several fields, ranging from robotics to wearable electronics.
author_names: Fabrizio Antonio Viola

Andrea Spanu

Pier Carlo Ricci

Annalisa Bonfiglio

Piero Cosseddu
title: Ultrathin, flexible and multimodal tactile sensors based on organic field effect transistors
venue: Scientific Reports
year: 2018

abstract: Organic field effect transistors (OFETs) using the polymer as the active layer are being intensively developed for flexible electronics including the gas sensor. However, as same as the other kinds of OFET gas sensors, its selectivity is not quite good enough. As we all know, the interfaces, including semiconductor/semiconductor and semiconductor/dielectric, play important roles in gas sensing. In this work, we introduced additional non conjugated polymer into the polymer active layer, to modulate the selectivity of polymer based OFET gas sensors to a certain gas. As a result, we can get two kinds of high selective gas sensors based on single polymer OFETs. Both the detection limit, response and selectivity of ammonia and nitrogen dioxide were significantly improved with different non conjugated polymers, and the device cost was also reduced by a factor of eight as compared to that using pure polymer material. By analyzing the electrical characteristics of OFET sensors and combining with the intrinsic characteristic of the non conjugated polymers, we systematically studied the mechanism of the performance improvement.
author_names: Shijiao Han

Zhirun Li

Xinming Zhuang

Junsheng Yu
title: Influence of polymer additional modulating layer on the selectivity performance of organic field effect transistor based gas sensor
venue: International Symposium on Advanced Optical Manufacturing and Testing Technologies (AOMATT)
year: 2019

abstract: Summary With the advent of the Internet of Things (IoT) era, flexible sensors are regarded as one of the most important technologies for the development of human friendly wearable devices. Organic field effect transistors (OFETs) based on conjugated polymers or small molecules are promising sensor platforms because they have various advantages, including high sensitivity, mechanical flexibility, and low cost fabrication processes. OFET based sensors enable continuous monitoring of external stimuli or target analytes with superior detection capabilities. This review describes the working principles and sensing mechanisms of various OFET based sensors, including chemical, biological, photo, pressure, and temperature sensors, and introduces the recent progress in this field. In addition, the technical challenges and future outlook of OFET based sensors for next generation flexible electronics are briefly discussed.
author_names: Yoon Ho Lee

Moonjeong Jang

Moo Yeol Lee

O Young Kweon

Joon Hak Oh
title: Flexible Field Effect Transistor Type Sensors Based on Conjugated Molecules
year: 2017

abstract: Vertical organic field effect transistors (VOFETs) have been explored with a higher current density, a faster switch speed, and a better air stability than conventional OFETs, which dramatically enhance the capability of driving an AMOLED backplane. Unfortunately, the state of the art of the fabrication of solution processed VOFETs is still very complicated, which can only focus at a single cell level. In this work, with the assistance of the inkjet print, the fabrication process of a solution processed VOFET was significantly simplified, and a solution processed VOFET array was fabricated for the first time, which exhibited excellent device performance and outstanding mechanical stability. More importantly, the VOFET arrays exhibited excellent photodetector properties, and a flexible image sensor based on VOFET arrays with multipoint visible photodetection and image recognition was demonstrated for the first time. Therefore, this novel process dramatically simplified the VOFET device fabrication process and a successfully realized array, which promoted the commercialization of VOFET and showed great potential in flexible display, multifunctional sensors, and wearable integrated circuits.
author_names: Yuan Fang

Xiaomin Wu

Shuqiong Lan

Jianfeng Zhong

Dawei Sun

Huipeng Chen

Tailiang Guo
title: Inkjet Printed Vertical Organic Field Effect Transistor Arrays and Their Image Sensors.
venue: ACS applied materials interfaces
year: 2018

title: Flexible and Wearable Sensors Based on Organic Field Effect Transistor Platforms
year: 2015

abstract: Here, we report flexible thermal sensors based on organic field effect transistors (OFETs) that are fabricated using polymeric channel and gate insulating layers on flexible polymer film substrates. Poly(3 hexylthiophene) and poly(methyl methacrylate) were used as the channel and gate insulating layers, respectively, whereas indium tin oxide coated poly(ethylene naphthalate) films (thickness 130 mm) were employed as the flexible substrates. Aluminum coated polymer films were attached on top of the channel parts in the flexible OFETs to block any influence by light illumination. The present flexible OFET based thermal sensors exhibited typical p type transistor characteristics at a temperature range of 25 100 degC, while the hole mobility of devices was linearly increased with the temperature. The drain current could be amplified at various temperatures by adjusting the gate and drain voltages. In particular, stable sensing performances were measured during the repeated approaching/retreating cycle with a heat source. The flexible OFET thermal sensors attached on human fingers could sense heat from human fingers as well as from approaching objects.
author_names: Myeonghun Song

Jooyeok Seo

Hwajeong Kim

Youngkyoo Kim
title: Flexible Thermal Sensors Based on Organic Field Effect Transistors with Polymeric Channel/Gate Insulating and Light Blocking Layers
venue: ACS omega
year: 2017