{"title":"Preparation and performance optimization of resistive flexible temperature sensors prepared by inkjet printing method","authors":"Shuilian Wang, Yuxuan Hu, Lisha Ma, Xiaoqing Cui, Yuan Peng, Jiahui Zheng, Lu Qiao, Haitao Ma, Rui Wang, Hongyan Zhang","doi":"10.1088/2058-8585/acd860","DOIUrl":"https://doi.org/10.1088/2058-8585/acd860","url":null,"abstract":"In recent years, inkjet printing has been widely used in the field of flexible sensor preparation. However, the effects of inkjet printing parameters and post-processing conditions on sensor performance have not been systematically investigated. Simple fabrication and optimized performance are eagerly desired for the practical use of temperature sensors in wearable healthcare devices. Herein, we report the resistive flexible temperature sensor fabricated on polyethylene terephthalate (PET) substrates with silver nanoparticles (AgNPs)-based ink using an inkjet printer. We have thoroughly investigated and optimized the sensitivity and linearity between the resistance and temperature of inkjet-printed temperature sensors by adjusting droplet spacing and curing conditions (temperature and time). In conclusion, the droplet spacing of 20 µm and the curing condition of 30 min at 150 °C were determined as the optimized parameters. With optimized process parameters, the temperature sensor has a high sensitivity of 0.084 °C−1 and a linear coefficient of 0.999 between relative resistance and temperature in the range of 30 °C–100 °C. Furthermore, it has a fast response time (7 s) and high stability against repeated bending deformation of 500 cycles. The prepared wearable sensors have potential application prospects in temperature monitoring.","PeriodicalId":51335,"journal":{"name":"Flexible and Printed Electronics","volume":" ","pages":""},"PeriodicalIF":3.1,"publicationDate":"2023-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43666006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A machine learning framework for process optimization in aerosol jet 3D printing","authors":"Yujia Liu, Shuai Yin, Zhixin Liu, Haining Zhang","doi":"10.1088/2058-8585/acd794","DOIUrl":"https://doi.org/10.1088/2058-8585/acd794","url":null,"abstract":"As a burgeoning three-dimensional (3D) printing technology, aerosol jet printing (AJP) technique has the characteristics of direct writing and customizing microelectronic components with flexible substrates. Therefore, it has been widely applied to manufacture different electronic devices. Although AJP has unique advantages over traditional methods, the electrical performance of printed electronic devices is significantly reduced because of the inferior printing qualities, such as high overspray, low level of line thickness and high level of edge roughness. Therefore, producing lines with high-controllability and high-aspect ratio is urgent for AJP technology. In this research, a machine learning scheme is developed for process optimization in AJP. In the proposed scheme, a support vector machine is combined with Latin hyper sampling to determine an optimal operating window of AJP, producing conductive lines with better edge definition and reduced overspray. Then, based on the identified 3D operating window, the conflicting relationship between the deposited line width and thickness was revealed based on the developed Gaussian process regression models. Following that, via a non-dominated sorting genetic algorithm, the conflicting printed line morphology was further optimized under dual conflicting targets for maximizing line thickness and customizing line width, which helps to produce high-controllability and high-aspect ratio lines for AJP. The optimization results demonstrated the validity of the proposed approach, which is beneficial to the systemic optimization of the entire printing process.","PeriodicalId":51335,"journal":{"name":"Flexible and Printed Electronics","volume":" ","pages":""},"PeriodicalIF":3.1,"publicationDate":"2023-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43761806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mohammad Naji Nassajfar, M. Välimäki, L. Hakola, K. Eiroma, K. Immonen, Mariam Abdulkareem, M. Horttanainen
{"title":"The effect of conductive ink alternation on the sustainability and functioning of printed electronics","authors":"Mohammad Naji Nassajfar, M. Välimäki, L. Hakola, K. Eiroma, K. Immonen, Mariam Abdulkareem, M. Horttanainen","doi":"10.1088/2058-8585/acd650","DOIUrl":"https://doi.org/10.1088/2058-8585/acd650","url":null,"abstract":"The demand for printed electronics (PE) is expected to increase for improved functionality and autonomy of products in the context of the Internet of Things, especially for sensing and communication. With this trend, the environmental performance of novel technologies is of growing importance, and researchers are exploring ways to make them more environmentally friendly using bio-based substrates and additive printing methods. Conductive inks have the highest environmental impact in the life cycle of PE, and there are two options to decrease the impact: increase recycling rates or replace commonly used silver inks with less impactful materials such as copper or graphite. With the current mixed waste management system, a higher recycling rate for silver is not achievable. Copper and graphite have a lower environmental impact than silver, however, the electrical conductivity of copper and graphite inks is lower than silver ink. This article introduces a double-parameter comparison to simultaneously assess the environmental and electrical conductivity of PE using three inks of silver, copper, and graphite inks. Then based on the technical feasibility, this study proposes suitable applications for each substrate and ink combination.","PeriodicalId":51335,"journal":{"name":"Flexible and Printed Electronics","volume":" ","pages":""},"PeriodicalIF":3.1,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44316697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Improved fatigue resistance in transfer-printed flexible circuits embedded in polymer substrates with low melting temperatures","authors":"Thomas Chalklen, Michael Smith, S. Kar‐Narayan","doi":"10.1088/2058-8585/acd402","DOIUrl":"https://doi.org/10.1088/2058-8585/acd402","url":null,"abstract":"Flexible electronics are of great interest and importance due to their applications in a range of fields, from wearable electronics to solar cells. Whilst resolutions of printed flexible electronics have been improving in recent years, there remain problems with mechanical fatigue and substrate cost, curtailing the use of such devices and resulting in increased cost and waste products. Here we present a novel method for improving the fatigue resistance of printed flexible electronics by a factor of ∼40 by sintering the electronics prior to transferring them into low-cost polymer substrates, such that they remain embedded. This method is demonstrated using circuits printed using silver nanoparticulate ink with an aerosol jet printer, and could be applicable to multiple different metallic inks. At the same time, this method can be used to transfer print circuits into polymers with low melting temperatures, without the need for otherwise detrimentally high sintering temperatures required for ink curing.","PeriodicalId":51335,"journal":{"name":"Flexible and Printed Electronics","volume":" ","pages":""},"PeriodicalIF":3.1,"publicationDate":"2023-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43721704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Liron Ben-Ari, A. Ben–Ari, Cheni Hermon, Y. Hanein
{"title":"Finger gesture recognition with smart skin technology and deep learning","authors":"Liron Ben-Ari, A. Ben–Ari, Cheni Hermon, Y. Hanein","doi":"10.1088/2058-8585/acd2e8","DOIUrl":"https://doi.org/10.1088/2058-8585/acd2e8","url":null,"abstract":"Finger gesture recognition (FGR) was extensively studied in recent years for a wide range of human-machine interface applications. Surface electromyography (sEMG), in particular, is an attractive, enabling technique in the realm of FGR, and both low and high-density sEMG were previously studied. Despite the clear potential, cumbersome electrode wiring and electronic instrumentation render contemporary sEMG-based finger gestures recognition to be performed under unnatural conditions. Recent developments in smart skin technology provide an opportunity to collect sEMG data in more natural conditions. Here we report on a novel approach based on soft 16 electrode array, a miniature and wireless data acquisition unit and neural network analysis, in order to achieve gesture recognition under natural conditions. FGR accuracy values, as high as 93.1%, were achieved for 8 gestures when the training and test data were from the same session. For the first time, high accuracy values are also reported for training and test data from different sessions for three different hand positions. These results demonstrate an important step towards sEMG based gesture recognition in non-laboratory settings, such as in gaming or Metaverse.","PeriodicalId":51335,"journal":{"name":"Flexible and Printed Electronics","volume":"8 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2023-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41495683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Joel Ndikumana, Jihoo Kim, Jun Young Kim, Dongjin Lee, Kunsik An
{"title":"A review on 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene based organic thin film transistor","authors":"Joel Ndikumana, Jihoo Kim, Jun Young Kim, Dongjin Lee, Kunsik An","doi":"10.1088/2058-8585/acd263","DOIUrl":"https://doi.org/10.1088/2058-8585/acd263","url":null,"abstract":"2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene (dif-TES-ADT) is a small molecule organic semiconductor that has drawn much interest as an active channel in organic thin film transistors (OTFTs). In particular, the solubility of dif-TES-ADT in numerous solvents and amorphous polymers, its chemical stability, and its ease in processing make it a supreme candidate for high performance devices. This review summarizes the progress in material crystallization and the film formation approach, including the surface treatment of Source/Drain metal electrodes with various self-assembled monolayers and the works on vertical phase segregation derived from blending dif-TES-ADT with various polymers. Electrical and environmental stabilities in dif-TES-ADT-based OTFTs and their origins are summarized. Finally, a discussion on the emerging applications of dif-TES-ADT OTFTs is explored. We believe that the individual effort summarized in this work will shed light on optimizing the electrical performance of dif-TES-ADT-based transistors and reveal their potential qualities, which will be useful to their applications in next-generation high performance organic electronics.","PeriodicalId":51335,"journal":{"name":"Flexible and Printed Electronics","volume":" ","pages":""},"PeriodicalIF":3.1,"publicationDate":"2023-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46142421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mutalifu Abulikemu, B. A. Tabrizi, Hamed M. Mofarah, Kimia Rezaei Shad, G. Jabbour
{"title":"Recyclable luminescent carbon dots nanopaper for flexible electronics","authors":"Mutalifu Abulikemu, B. A. Tabrizi, Hamed M. Mofarah, Kimia Rezaei Shad, G. Jabbour","doi":"10.1088/2058-8585/acd200","DOIUrl":"https://doi.org/10.1088/2058-8585/acd200","url":null,"abstract":"The use of sustainable materials in high-tech devices is one way to decrease the carbon footprint and tackle global climate change. We first synthesized blue-emissive carbon dots (CDs) from biocompatible onion inner epidermal cells using solvothermal method. Then, cellulose nanofiber was prepared by TEMPO oxidization, followed by homogenization from soft wood source. Finally, the blue emissive CDs-cellulose nanofibers-based nanopaper was fabricated by simple roller-coating approach, and its optical and morphological properties were investigated by transmittance, photoluminescence, fourier-transform infrared (FTIR) and scanning electron microscopy techniques. The results indicate that nanopapers have a high light emission, and that their transparency may be easily adjusted by varying the proportion of CDs content. These nanopapers can be incorporated into flexible and stretchable electronics and optical sensor platforms.","PeriodicalId":51335,"journal":{"name":"Flexible and Printed Electronics","volume":" ","pages":""},"PeriodicalIF":3.1,"publicationDate":"2023-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41523484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"In-mold electronics applications: the control of ink properties through the use of mixtures of electrically conductive pastes","authors":"M. Miliciani, G. Mendicino, M. DeMeuse","doi":"10.1088/2058-8585/acd129","DOIUrl":"https://doi.org/10.1088/2058-8585/acd129","url":null,"abstract":"Polymer thick films compatible with a thermoforming process are the key components to realize the next generation of human–machine interface and lighting with a 3D custom shape through an in-mold process. The purpose of this study is to demonstrate that a tailored combination of commercial pastes can offer the manufacturer more freedom in developing smart electronic devices. A four-point probe instrument was used to measure the resistivity of the printed circuit. We used the same formed printed sample to estimate the level of elongation under the thermoforming process due to the all-in-one screen design developed for the study. The important objective of this work was to form a paste which should withstand such operations without losing physical properties such as conductivity or adhesion or getting lines cracked.","PeriodicalId":51335,"journal":{"name":"Flexible and Printed Electronics","volume":" ","pages":""},"PeriodicalIF":3.1,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49630264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. N. Aidit, Fazliyatul Azwa Md Rezali, Nurul Hidayah Mohamad Nor, N. Yusoff, Li-Ya Ma, S. F. Wan Muhamad Hatta, N. Soin
{"title":"Hydrothermal synthesis of zinc oxide/PEDOT:PSS composite for flexible temperature sensor application","authors":"S. N. Aidit, Fazliyatul Azwa Md Rezali, Nurul Hidayah Mohamad Nor, N. Yusoff, Li-Ya Ma, S. F. Wan Muhamad Hatta, N. Soin","doi":"10.1088/2058-8585/acd06e","DOIUrl":"https://doi.org/10.1088/2058-8585/acd06e","url":null,"abstract":"A flexible and printable temperature sensor was proposed for a fast detection of temperature measurements. A hybrid composite of zinc oxide (ZnO) and a conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonicacid) (PEDOT:PSS) was utilized as the temperature-sensing layer. An interdigitated electrodes structure based on silver (Ag) ink was used to electrically connect the composite through a facile drop-casting technique. A standout aspect of this work is the presentation of ZnO/PEDOT:PSS as a temperature-sensing layer. The PEDOT:PSS flakes were connected by hydrothermally prepared ZnO nanorods, which increased the composite sheets’ electrical conductivity. The linearity, sensitivity, stability and dynamic response of the flexible sensor were examined from a temperature of 29 °C–60 °C. The sensor has high sensitivity of 1.06% °C−1 with response and recovery times of 5 s and 12.7 s, respectively. This work clearly demonstrates the potential of ZnO/PEDOT:PSS composite for flexible temperature sensor and adds to the rapidly expanding field of personalized mobile healthcare.","PeriodicalId":51335,"journal":{"name":"Flexible and Printed Electronics","volume":" ","pages":""},"PeriodicalIF":3.1,"publicationDate":"2023-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41945717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Flexible planar capacitive devices for hydration and sweat sensing","authors":"Shayan Naveed, Jinzhong Ma, Shazrah Shahzad, Xiaoming Wu, Tianling Ren","doi":"10.1088/2058-8585/acd011","DOIUrl":"https://doi.org/10.1088/2058-8585/acd011","url":null,"abstract":"Skin is one of the most complex structures in the body, with many physiological functions. Skin acts as the barrier or an interface between the external environment and internal organs. Hydration within the skin is varied, known as the skin’s water-loading. Perspiration occurs when watery fluid is secreted through the eccrine and apocrine glands. Flexible epidermal sensors are fabricated, which can be used to measure skin hydration and perspiration (sweat) as these sensors need to be skin-conformable. Polyimide and polydimethylsiloxane are used as they are flexible and skin compliant, and the sensing layer is formed on them. The sensitivity of hydration sensors was in the range of 0.002–0.0046/%, while for sweat sensors, it was in the range of 0.092–0.116 μl−1. Stability tests indicated that external factors such as environment or physical deformation and skin curvature do not affect the performance of the as-prepared sensors. The sensitivity and stability results of the planar capacitor are highly suitable for flexible hydration and sweat-sensing applications. The proposed sensors offer an outstandingly good option for incorporation into wearable systems for physical personal health monitoring. In the future, we plan to integrate these sensors on a single substrate to create a multimodal device.","PeriodicalId":51335,"journal":{"name":"Flexible and Printed Electronics","volume":" ","pages":""},"PeriodicalIF":3.1,"publicationDate":"2023-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44485912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}