IEEE Journal on Flexible Electronics最新文献

{"title":"Design and Implementation of N-Type-Only LTPS-TFT Voltage Reference Circuits for Flexible Electronics","authors":"Chao Wang;Yiyang Chen;Wangzilu Lu;Jiajie Huang;Yuting Hou;Jian Zhao;Hui Wang;Chen Jiang;Yongfu Li","doi":"10.1109/JFLEX.2026.3668761","DOIUrl":"https://doi.org/10.1109/JFLEX.2026.3668761","url":null,"abstract":"This article details the design and simulation-based evaluation of three distinct <inline-formula> <tex-math>$N$ </tex-math></inline-formula>-type-only low-temperature polycrystalline-silicon thin-film transistor (LTPS-TFT) voltage reference circuits, tailored for the specific demands of flexible electronic systems. Addressing the inherent design challenges in TFT technology, these circuits employ a common strategy: generating a current with a negative temperature coefficient to compensate for proportional-to-absolute-temperature (PTAT) voltage characteristics. Comprehensive post-layout and statistical Monte Carlo (MC) simulation results highlight that the first of the proposed configurations achieves superior performance, exhibiting a temperature coefficient (TC) of 34.03 ppm/°C, a line sensitivity of 0.61%/V, and a power supply rejection ratio (PSRR) of −42.34 dB. This study presents new circuit-level approaches for achieving reliable voltage references in flexible applications, thereby advancing the development of high-performance, flexible electronic systems.","PeriodicalId":100623,"journal":{"name":"IEEE Journal on Flexible Electronics","volume":"5 4","pages":"107-115"},"PeriodicalIF":0.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147734138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"IEEE Journal on Flexible Electronics Publication Information","authors":"","doi":"10.1109/JFLEX.2026.3678445","DOIUrl":"https://doi.org/10.1109/JFLEX.2026.3678445","url":null,"abstract":"","PeriodicalId":100623,"journal":{"name":"IEEE Journal on Flexible Electronics","volume":"5 4","pages":"C2-C2"},"PeriodicalIF":0.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11493911","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147734755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Digital Design Techniques for IGZO-Based Circuits","authors":"Sven Baerten;Yari Nowicki;Jelle Biesmans;Kris Myny","doi":"10.1109/JFLEX.2026.3658022","DOIUrl":"https://doi.org/10.1109/JFLEX.2026.3658022","url":null,"abstract":"This article explores two optimization strategies for digital circuits based on indium–gallium–zinc–oxide (IGZO) thin-film transistors (TFTs). The first method focuses on clock tree synthesis (CTS) and its impact on performance. To evaluate the effectiveness of CTS, a 32-bit counter incorporating a Brent–Kung adder (BKA) was designed and fabricated. Implementing the clock tree improved the maximum operating frequency up to 50%. The second optimization strategy is a mixed standard cell library that integrates both high-performance (HP) and low-power (LP) cells, using a two-stage resistor-load logic (2RLL) topology. The HP cells will be placed along the critical paths of the integrated circuits (ICs), while LP cells will be used in noncritical areas. To validate this approach, two MOS 6502 microprocessor versions were developed: one with only HP cells and another with the mixed library. Our findings indicate a threefold reduction in power consumption when employing the mixed library during the digital flow at comparable clock speeds. In addition, we developed what is, to our knowledge, the fastest IGZO-TFT microprocessor reported to date, achieving a clock frequency of 295 kHz, and the lowest power-consuming microprocessor in this technology, marking the first IGZO-CPU to operate in the sub-mW range at <inline-formula> <tex-math>$580~mu $ </tex-math></inline-formula>W.","PeriodicalId":100623,"journal":{"name":"IEEE Journal on Flexible Electronics","volume":"5 4","pages":"127-133"},"PeriodicalIF":0.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11363401","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147734743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Hybrid EOG System Featuring Flexible a-IGZO TFTs and a 180 nm CMOS IC","authors":"Mohammad Zulqarnain;Stefano Stanzione;Elisabetta Peri;Steve Smout;Myriam Willegems;Pieter Harpe;Kris Myny;Eugenio Cantatore","doi":"10.1109/JFLEX.2026.3669472","DOIUrl":"https://doi.org/10.1109/JFLEX.2026.3669472","url":null,"abstract":"Flexible wearable sensors are becoming increasingly popular due to their capability to monitor physiological signals while ensuring high user comfort. Wearable sensors built using only flexible electronics result in inferior system performance due to the inherent limitations of flexible technologies. Flexible hybrid electronics (FHEs) combine the strengths of flexible technologies (low cost, larger area coverage, and user comfort) with the high performance and energy efficiency of silicon-integrated circuits (Si ICs). Here, an FHE system is described that addresses the challenge of system functions partitioning between flexible and Si subsystems. The presented design approach is applied in this work to a multichannel electro-oculography (EOG) system, but can be expanded to various FHE application domains. The proof of concept fully integrated eight-channel FHE EOG system exploits a front-end in a-IGZO TFT technology, interfaced with a custom Si IC that supports the front-end and provides conversion of the acquired signals to the digital domain. In this way, the low cost, flexible form factor, and the large area character of the flexible thin-film transistor (TFT) technology are leveraged, while exploiting at the same time the accuracy, computational capability, and energy efficiency of the Si IC. We propose a hybrid high-pass filter (hHPF) as an interface between the electrodes and the front-end, whereby TFTs and capacitors on foil are controlled by the Si IC. The hybrid approach exploits the capabilities of flexible electronics to bring functionality close to the electrodes and its potential to cope with a high number of sensor channels, with the better precision of CMOS, enabling a fully integrated filter without discrete components. The TFT front-end converts the input signal voltages to a pulsewidth-modulated (PWM) representation, which is then quantized in the Si IC, to provide a digital output. The Si IC enables conversion to the digital domain with much higher efficiency compared to state-of-the-art TFT solutions. The digital output is further used in an algorithm for feature extraction and classification to detect the desired signals. The experimental electrical characterization of the system demonstrates an input-referred noise of &lt;inline-formula&gt; &lt;tex-math&gt;$6.68~mu $ &lt;/tex-math&gt;&lt;/inline-formula&gt;&lt;inline-formula&gt; &lt;tex-math&gt;$mathrm{V}_{rms}$ &lt;/tex-math&gt;&lt;/inline-formula&gt; in a 1–30 Hz band, with a chopping frequency of 1 kHz. The input impedance offered by the integrated hHPF is 6.88 G&lt;inline-formula&gt; &lt;tex-math&gt;$Omega $ &lt;/tex-math&gt;&lt;/inline-formula&gt; at 0.089 Hz (with multiplexing disabled). The total power consumption per channel is &lt;inline-formula&gt; &lt;tex-math&gt;$84~mu $ &lt;/tex-math&gt;&lt;/inline-formula&gt;W. In vivo experiments have also been performed against a gold standard (a commercial bio-potential amplifier) to confirm a faithful representation of the eye activities. The signals acquired during in vivo experiments are successfully classified usin","PeriodicalId":100623,"journal":{"name":"IEEE Journal on Flexible Electronics","volume":"5 4","pages":"95-106"},"PeriodicalIF":0.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147734751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"IEEE Journal on Flexible Electronics Publication Information","authors":"","doi":"10.1109/JFLEX.2026.3668892","DOIUrl":"https://doi.org/10.1109/JFLEX.2026.3668892","url":null,"abstract":"","PeriodicalId":100623,"journal":{"name":"IEEE Journal on Flexible Electronics","volume":"5 3","pages":"C2-C2"},"PeriodicalIF":0.0,"publicationDate":"2026-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11433224","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147429308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ultrathin Flexible Dual-Band Dual-Polarized Antenna for mmWave 5G Wearable Electronics","authors":"Saeid Alamdar;Sahar Bagherkhani;Franco De Flaviis;Soheil Saadat","doi":"10.1109/JFLEX.2026.3674064","DOIUrl":"https://doi.org/10.1109/JFLEX.2026.3674064","url":null,"abstract":"An ultrathin, dual-band, dual-polarized antenna with improved isolation between the two polarizations, designed on a 248-<inline-formula> <tex-math>$mu $ </tex-math></inline-formula>m thick flexible printed circuit (FPC) board, is presented in this article. In thin flexible millimeter-wave (mmWave) antennas, maintaining high isolation between orthogonal polarizations across two-frequency bands is particularly challenging due to strong coupling through the patch structure and limited substrate thickness. To address this issue, an asymmetric dual-polarized patch antenna employing a partial differential feeding technique is proposed, in which only one port is differentially fed using a wideband coupled-line phase shifter integrated with a T-junction. This configuration effectively suppresses coupling and enhances isolation. The proposed antenna operates simultaneously in the 27.5–28.7-GHz and 37–38.5-GHz bands, achieving measured isolation better than −25 dB between the two polarizations.","PeriodicalId":100623,"journal":{"name":"IEEE Journal on Flexible Electronics","volume":"5 5","pages":"152-160"},"PeriodicalIF":0.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147865488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"IEEE Journal on Flexible Electronics Publication Information","authors":"","doi":"10.1109/JFLEX.2026.3689834","DOIUrl":"https://doi.org/10.1109/JFLEX.2026.3689834","url":null,"abstract":"","PeriodicalId":100623,"journal":{"name":"IEEE Journal on Flexible Electronics","volume":"5 5","pages":"C2-C2"},"PeriodicalIF":0.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11514872","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147865496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Gain-Boosted Cross-Coupled Amplifier Using a-IGZO TFTs on a Flexible Substrate","authors":"Smrutilekha Samanta;Vaishali Choudhary;Pydi Ganga M. Bahubalindruni","doi":"10.1109/JFLEX.2026.3669885","DOIUrl":"https://doi.org/10.1109/JFLEX.2026.3669885","url":null,"abstract":"This article presents a novel gain-boosted cross-coupled differential amplifier using only n-type amorphous indium–gallium–zinc-oxide (a-IGZO) thin-film transistor (TFT) technology. The proposed single-stage amplifier design exploits a cross-coupled regulated cascode topology with an auxiliary amplifier and capacitive bootstrapping load to improve the gain. In addition, chopper stabilization and common-mode (CM) feedback sensing techniques are introduced to reduce the low-frequency noise and to improve the CM rejection ratio (CMRR), respectively, without compromising the output voltage swing. The circuit is fabricated on a 27-<inline-formula> <tex-math>$mu $ </tex-math></inline-formula>m-thick flexible polyimide substrate. From measurements, the circuit has shown a voltage gain of 35.85 dB, a phase margin (PM) of 65.4°, a CMRR of 68.4 dB, and power consumption of <inline-formula> <tex-math>$320~mu $ </tex-math></inline-formula>W at a power supply voltage of 4 V. In addition, the circuit has shown a gain–bandwidth product (GBWP) of 345 kHz, a figure of merit (FOM) of 1.86 MHz/mW, and a noise efficiency factor (NEF) of 27.48. The performance of the amplifier is validated with the electromyography (EMG) signals, using 3M gel-based electrodes. This amplifier will find potential applications in biosignal acquisition systems for wearable devices.","PeriodicalId":100623,"journal":{"name":"IEEE Journal on Flexible Electronics","volume":"5 5","pages":"167-174"},"PeriodicalIF":0.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147865435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inkjet-Printing With Micrometer Resolution on Paper for Flexible RF Applications","authors":"Fawzi Bouakkaz;Riccardo Sargeni;Sylvie Lepilliet;Simon Skrzypczak;Emiliano Pallecchi;Gianluca Fiori;Henri Happy","doi":"10.1109/JFLEX.2026.3668145","DOIUrl":"https://doi.org/10.1109/JFLEX.2026.3668145","url":null,"abstract":"Geometry is a critical factor in radio frequency design that directly affects the performance and efficiency of RF components and systems. The characteristic impedance and the propagation constant of transmission lines are affected by the conductor width, spacing, and the dielectric properties. In addition, performance metrics such as insertion loss and bandwidth of microwave filters are also affected by the geometric configuration of resonant elements. This article explores the use of a noncommercial inkjet printer prototype to fabricate high-frequency devices with microscale precision, achieving high-resolution gaps, uniform spacing as small as <inline-formula> <tex-math>$9~mu $ </tex-math></inline-formula>m, conductor widths of <inline-formula> <tex-math>$50~mu $ </tex-math></inline-formula>m, and a filter that operates at frequencies up to 50 GHz. The chosen substrate is paper as a sustainable, environmentally friendly, and flexible platform that offers adaptability for RF applications in dynamic environments. The design, fabrication, and measurements of coplanar waveguides (CPWs) transmission lines and passband filter operating at a central frequency of 25 GHz are presented. The printed CPWs demonstrate attenuation of 0.5 dB/mm at 10 GHz and 1.1 dB/mm at 50 GHz. The fabricated bandpass filter achieves an insertion loss of −5 dB in the bandpass. The performance of the printed filters was studied with respect to the printing and annealing conditions, and it was compared to equivalent filter designs printed on a PET substrate.","PeriodicalId":100623,"journal":{"name":"IEEE Journal on Flexible Electronics","volume":"5 5","pages":"161-166"},"PeriodicalIF":0.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147865501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Automated Paper Strip Reader (APSR): A Reliable Low-Cost Solution for Colorimetric Detection","authors":"Tejal Shinde;Prachi Bhoir;Jagannath Nirmal;Ninad Mehendale","doi":"10.1109/JFLEX.2026.3677153","DOIUrl":"https://doi.org/10.1109/JFLEX.2026.3677153","url":null,"abstract":"Manual interpretation of colorimetric test strips is prone to substantial variability due to human error and sensitivity to surrounding illumination conditions, resulting in limited diagnostic reliability at the point-of-care (POC) (only 60.7% accuracy in our evaluation). To overcome these issues, we designed an automated paper strip reader (APSR) built on a Raspberry Pi 4B platform. The device integrates a closed chamber with uniform LED illumination, an USB camera, and Python-based image processing algorithms to quantify 15 water quality parameters, including pH, nitrate, chloride, and selected heavy metals. Images are captured under controlled lighting and analyzed through parameter-specific calibration curves, with results displayed via a touchscreen interface. Validation using diverse water samples showed that APSR achieved an overall accuracy of 88.7%, outperforming human interpretation (60.7%). In particular, the APSR provided perfect detection accuracy (100%) for iron and copper, compared to only 63% and 40% by human readers, respectively. Each test requires approximately 5 s, with the device costing less than U.S. 150 to assemble, and offering one-click data export. This cost-effective automated system provides a robust solution for reliable POC testing in low-resource environments, aligning with the World Health Organization (WHO) ASSURED criteria for diagnostic devices.","PeriodicalId":100623,"journal":{"name":"IEEE Journal on Flexible Electronics","volume":"5 5","pages":"175-185"},"PeriodicalIF":0.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147865483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}