{"title":"Recent advances in transfer printing of inorganic thin films for flexible hybrid systems","authors":"Haneol Lee","doi":"10.1186/s40486-025-00237-1","DOIUrl":"10.1186/s40486-025-00237-1","url":null,"abstract":"<div><p>The evolution of human–machine interfaces (HMI) toward more immersive and intuitive forms, such as wearable devices and augmented reality systems, demands the development of high-performance flexible electronics. Heterogeneous integration, which combines diverse inorganic materials and functional devices onto unconventional substrates, is the core strategy for realizing these next-generation systems. The success of this approach, however, critically hinges on the ability to precisely transfer and assemble vast quantities of micro-scale components. This paper reviews the state-of-the-art in inorganic thin-film transfer technologies, which are the essential enablers for this paradigm shift. We systematically categorize and discuss the mechanisms, advantages, and drawbacks of three primary approaches: physical, chemical, and self-assembly transfer methods. Furthermore, we introduce recent applications of semiconductor devices developed via these techniques. The continued advancement of these transfer technologies is poised to catalyze transformative innovations in how users interact with the digital world, fundamentally reshaping applications in medicine, personal computing, and beyond.</p></div>","PeriodicalId":704,"journal":{"name":"Micro and Nano Systems Letters","volume":"13 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://mnsl-journal.springeropen.com/counter/pdf/10.1186/s40486-025-00237-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145210541","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}
Jeong Hyeon Kim, Min Jae Hwang, Ha Yoon Jo, So Yeon Choi, Seong Hyeon Park, Haneol Lee
{"title":"Portable surface acoustic wave sensor systems for microplastic detection in beverages","authors":"Jeong Hyeon Kim, Min Jae Hwang, Ha Yoon Jo, So Yeon Choi, Seong Hyeon Park, Haneol Lee","doi":"10.1186/s40486-025-00236-2","DOIUrl":"10.1186/s40486-025-00236-2","url":null,"abstract":"<div><p>The escalating global plastic production (~ 390 million tons in 2022) and subsequent environmental release of microplastics necessitate urgent advancements in real-time detection technologies. While optical methods (Raman spectroscopy, FTIR) dominate current microplastic analysis, their reliance on bulky instrumentation limits field applications. This study presents a portable surface acoustic wave (SAW) sensor system for real-time microplastic detection in beverages. A biocompatible aluminum interdigital transducer (IDT) array (40 pairs, 30 μm gap) was fabricated on piezoelectric substrates (InGaN and PMN-PT), with SU-8 passivation selectively exposing sensing regions to minimize liquid-phase interference. Material characterization confirmed substrate crystallinity and composition, revealing InGaN’s superior sensitivity, estimated to be ~ 0.168 MHz/(mg/mL) than the PMN-PT-based device. The integrated system employs an InGaN-based oscillator circuit resonating at 39.06 MHz, enabling standalone operation without external signal generators. A threshold-driven LED interface (red/green for ≥ / < 0.25 mg) provides intuitive readouts, while universal printed circuit board (PCB) integration ensures portability. This work demonstrates a scalable platform for on-site microplastic monitoring, addressing critical gaps in consumer safety and environmental health.</p></div>","PeriodicalId":704,"journal":{"name":"Micro and Nano Systems Letters","volume":"13 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://mnsl-journal.springeropen.com/counter/pdf/10.1186/s40486-025-00236-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145100665","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}
Dong Yun Kim, Md Selim Reza, Ahmad Abdus Samad, Zahidul Islam, Ji Won Go, Jae Yeong Park
{"title":"A highly stable and flexible ion-selective patch sensor for real-time sweat Na+ and K+ monitoring","authors":"Dong Yun Kim, Md Selim Reza, Ahmad Abdus Samad, Zahidul Islam, Ji Won Go, Jae Yeong Park","doi":"10.1186/s40486-025-00235-3","DOIUrl":"10.1186/s40486-025-00235-3","url":null,"abstract":"<div><p>Wearable electrochemical biosensors based on solid-contact ion-selective electrodes (SC-ISEs) have emerged as a promising platform for non-invasive, real-time monitoring of sweat electrolytes. However, conventional ion-selective biosensors often suffer from potential drift and long-term instability due to the formation of undesired aqueous layers and interference from other ions. To overcome these challenges, we present a flexible and highly stable SC-ISE patch sensor for simultaneous detection of Na⁺ and K⁺ ions in sweat. The sensor employs a laser-induced graphene (LIG) electrode patterned directly onto a Ti<sub>3</sub>C<sub>2</sub>T<sub>x</sub> -MXene/PVDF nanofiber mat, which was fabricated using electrospinning followed by CO<sub>2</sub> laser carbonization. The MPNFs/LIG@TiO<sub>2</sub> hybrid structure exhibits excellent electrical conductivity, high electrochemical surface area, and enhanced hydrophobicity, all contributing to reduced potential drift and improved signal stability.</p><p>Ion-selective membranes (ISMs) based on a PVC-SEBS blend were drop-cast onto the LIG electrode to achieve selective ion recognition, while a double-sided PET tape substrate ensured mechanical flexibility and skin conformity. The addition of TiO<sub>2</sub> nanoparticles during the thermal laser oxidation process induced π-π interactions within the composite, resulting in a robust 3D porous electrode architecture with enhanced ion transport and interfacial contact. The fabricated Na<sup>+</sup> and K<sup>+</sup> sensors demonstrated near-Nernstian sensitivities of 48.8 mV/decade and 50.5 mV/decade, respectively, within physiologically relevant sweat concentration ranges. Additionally, the sensors showed excellent long-term stability with minimal potential drift (0.04 mV/h for Na<sup>+</sup> and 0.08 mV/h for K<sup>+</sup>), along with rapid response and high accuracy. The use of scalable, low-cost laser engraving and solution casting techniques enables reliable batch fabrication, making the proposed sensor patch a strong candidate for integration into wearable platforms aimed at continuous electrolyte monitoring during physical activity.</p></div>","PeriodicalId":704,"journal":{"name":"Micro and Nano Systems Letters","volume":"13 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://mnsl-journal.springeropen.com/counter/pdf/10.1186/s40486-025-00235-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145037360","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":"Sensing and monitoring system for diagnosis and therapy of obstructive sleep apnea","authors":"Won Ick Jang","doi":"10.1186/s40486-025-00234-4","DOIUrl":"10.1186/s40486-025-00234-4","url":null,"abstract":"<div><p>This study aims to develop and evaluate a wearable sensing and monitoring system for the diagnosis and therapy of obstructive sleep apnea (OSA), a disorder characterized by recurrent upper airway collapse during sleep that leads to sleep fragmentation and oxygen desaturation. The proposed system integrates multivariate biosensor modules—including flow, acceleration, temperature, humidity, and pH sensors—into an oral appliance designed to maintain the mandible in a forward position, thereby preventing airway collapse. A convolutional neural network was employed to analyze biosignals for detecting OSA-related events, bruxism, sleeping posture, and sleep patterns. In feasibility tests, the system accurately classified body postures, monitored heart rate variations, detected bruxism with up to 94% accuracy in non-bruxism segments and 89.47% in bruxism segments, and quantified sleep quality over extended monitoring periods. These results demonstrate that the proposed system offers a practical, non-invasive, and cost-effective alternative to conventional polysomnography or continuous positive airway pressure therapy, enabling continuous at-home screening and management of OSA, particularly in mild-to-moderate cases.</p></div>","PeriodicalId":704,"journal":{"name":"Micro and Nano Systems Letters","volume":"13 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://mnsl-journal.springeropen.com/counter/pdf/10.1186/s40486-025-00234-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145011783","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":"Anti CD19-PAMAM G4-PEG nano-complex as a potential targeted delivery system against leukemia","authors":"Shirin Mahmoodi Khatoon Abadi, Pouria Ahmadisimab, Seyedeh Fatemeh Hosseini, Asghar Narmani, Sepideh Khaleghi, Hanieh Jafari, Javad Mohammadnejad","doi":"10.1186/s40486-025-00232-6","DOIUrl":"10.1186/s40486-025-00232-6","url":null,"abstract":"<div><p>In recent decades, cancer has been dramatically leading to high amounts of death all over the world, and leukemia is one of the progressing cancers that should stop somehow. To prevent its health-threatening incidence, nanoparticle-based targeting drug delivery systems are crucially needed. As a result, the polyethylene glycol (P) modified and anti-CD19 antibody (Ab) decorated polyamidoamine (PAMAM G4: P) dendritic nano-complex was developed for effective delivery of sodium butyrate drug (D) to Reh6 leukemia cells in this research work. After the synthesis of the nano-complex, several analytical devices such as FT-IR, TGA, DLS, Zeta potential analyzer, and TEM were applied to the qualification and quantification of syntheses and conjugations. Nanometric size (less than 50 nm in diameter), −4.2 mV surface charge, high drug loading efficiency (14.42%), and appropriate controlled drug release (less than 50% within first 8 h at pH 7.4) profile at different pHs were observed for Ab-P-P-D nano-complex. In the biomedical phase, the MTT assay demonstrated 13.04% cell viability at 800 nM after 24 h of treatment. IC50 was obtained for 100 nM concentration. The Bcl2 and caspase9 genes were indicated less than half and more than 15 folds of expressions at post-treatment time, respectively. The cell cycle arrest was drastically depicted more than 15 folds of cell Reh6 suppression in comparison to control. Moreover, the leukemia cells treated with Ab-P-P-D have demonstrated 42.39% apoptosis which was potentially several folds more than control. These data have verified the potency of the nanocarrier as an effective drug delivery system.</p></div>","PeriodicalId":704,"journal":{"name":"Micro and Nano Systems Letters","volume":"13 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://mnsl-journal.springeropen.com/counter/pdf/10.1186/s40486-025-00232-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144896900","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}
Alberto Martín-Pérez, Stefano Stassi, Carlo Ricciardi
{"title":"Suspended Microchannel resonators with integrated electrodes for thermal and electrical characterization of liquids","authors":"Alberto Martín-Pérez, Stefano Stassi, Carlo Ricciardi","doi":"10.1186/s40486-025-00233-5","DOIUrl":"10.1186/s40486-025-00233-5","url":null,"abstract":"<div><p>Suspended microchannel resonator (SMR) has been demonstrated as a versatile technique, allowing to measure mechanical, morphological or even optical properties of cells. However, physical properties of cells may substantially change depending on the chemical composition of the suspension medium. Therefore, it is essential developing novel multiparametric techniques able to provide a complete understanding of the biological samples by characterizing also the liquid in which the cells are suspended. In this work we both theoretically and experimentally introduce a novel electro-mechanical sensing technique using SMR devices with integrated electrodes that allow measuring different physicochemical properties of the liquid sample as thermal conductivity, dielectric constant, electrical conductivity or even concentration of ions. These measured liquid properties can ultimately be used to complement other typical SMR measurements, such as mass. Moreover, we show that this electro-mechanical approach can be also used as a transduction method and as a way of tuning the mechanical resonance frequency.</p></div>","PeriodicalId":704,"journal":{"name":"Micro and Nano Systems Letters","volume":"13 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://mnsl-journal.springeropen.com/counter/pdf/10.1186/s40486-025-00233-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144810816","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}
Hyeonggeun Kim, Ingyu Lee, Swati Panda, Sugato Hajra, ByeongJun Jeong, Jeonggyu Seo, Kushal Ruthvik Kaja, Mohamed A. Belal, Venkateswaran Vivekananthan, Hoe Joon Kim
{"title":"Smart gloves-based triboelectric nanogenerator for sign language detection","authors":"Hyeonggeun Kim, Ingyu Lee, Swati Panda, Sugato Hajra, ByeongJun Jeong, Jeonggyu Seo, Kushal Ruthvik Kaja, Mohamed A. Belal, Venkateswaran Vivekananthan, Hoe Joon Kim","doi":"10.1186/s40486-025-00231-7","DOIUrl":"10.1186/s40486-025-00231-7","url":null,"abstract":"<div><p>Sign language is frequently used to facilitate communication between the normal and individuals having speaking and hearing difficulties. In this work, a triboelectric nanogenerator (TENG) based on smart gloves was designed for a self-powered sign language detection system. The TENG was fabricated using flexible materials like copper, aluminum electrodes, and polyethylene fabric (PE). To accommodate many finger positions and the backside of fingers as separate channels, the TENG was made to be both circular and rectangular in shape. Employing PE fabric as an active layer, these TENG devices can successfully harvest biomechanical energy from finger motions while being comfortable for the fingers. The TENG device with 4 cm × 4 cm dimensions demonstrated the highest voltage and current of 220 V and 750 nA, respectively, whereas the highest power of the device is 65 μW at 500 MΩ resistance. The TENG device was effectively used to charge various capacitors and power a low-power digital watch. The electrical outputs from performing the sign language gestures were collected using the TENG and translated into digital signals using Python. This sign-language detection based on the TENG system is completely tailorable, easy to fabricate, low-cost, and wearable. The emergency sign languages can be easily translated into text signals and can be recognized by non-signers, and take immediate action for the required scenarios.</p></div>","PeriodicalId":704,"journal":{"name":"Micro and Nano Systems Letters","volume":"13 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://mnsl-journal.springeropen.com/counter/pdf/10.1186/s40486-025-00231-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145168328","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}
Mohamed Ahmed Belal, Sugato Hajra, Swati Panda, Kushal Ruthvik Kaja, Kyeong Jun Park, Hoe Joon Kim
{"title":"Spray-printed ZnO thin film for high-sensitivity NO2 gas sensing","authors":"Mohamed Ahmed Belal, Sugato Hajra, Swati Panda, Kushal Ruthvik Kaja, Kyeong Jun Park, Hoe Joon Kim","doi":"10.1186/s40486-025-00230-8","DOIUrl":"10.1186/s40486-025-00230-8","url":null,"abstract":"<div><p>The controlling and precise detection of nitrogen dioxide (NO<sub>2</sub>) gas is important in many industrial processes such as medical, petrochemical, and agriculture. Therefore, this study investigates the gas sensing performance of zinc oxide (ZnO) nanosheets prepared using a hydrothermal approach. The morphology and structure of the as-prepared material were analyzed using analysis techniques, including transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The ZnO ink was spray printed in a square design onto an oxidized silicon wafer substrate, which includes a lithographically designed interdigitated pattern. ZnO nanosheets exhibited superior gas sensing performance, which is 5298% for sensor response and 96 and 600 s for response and recovery times, respectively, at 150 °C and 100 ppm of NO<sub>2</sub> gas. The previous results emphasize applying the proposed spray printing technique in different applications because of straightforward, versatile for different substrates, and cost-effective.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":704,"journal":{"name":"Micro and Nano Systems Letters","volume":"13 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://mnsl-journal.springeropen.com/counter/pdf/10.1186/s40486-025-00230-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145162392","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}
Mikel Hualde-Otamendi, Carlos A. De La Cruz-Blas, J. Carlos Castellano-Aldave, Alfonso Carlosena
{"title":"Power converter for ultra low-frequency and low-voltage energy harvesters","authors":"Mikel Hualde-Otamendi, Carlos A. De La Cruz-Blas, J. Carlos Castellano-Aldave, Alfonso Carlosena","doi":"10.1186/s40486-025-00229-1","DOIUrl":"10.1186/s40486-025-00229-1","url":null,"abstract":"<div><p>Energy conversion mechanisms present in some harvesters are only able to provide very low voltage (mV) and frequency (few Hz) electrical signals, which may also have a bipolar nature (AC). These characteristics make unusable most conventional power converters to extract from them a DC voltage. This letter describes an autonomous self-starting ultra-low voltage and frequency AC-DC converter that can start the operation for AC signals around 25 mV, and below 10 Hz. The converter has been designed with ultra-low vibration harvesters in mind, but is also of application to, for instance, thermoelectric generators (TEG). The circuit is basically an oscillator driven by the harvester output, which therefore converts a low-frequency and low-voltage signal into large signal oscillation amenable for further DC conversion. The proposed circuit is based on the classical Hartley oscillator, which is modified in a nontrivial configuration, and optimized to be able to operate with bipolar, low frequency and voltage driving signals. This is achieved with a minimum number of passive components and a single JFET transistor. A practical prototype has been fabricated, and measurement results are obtained, demonstrating the feasibility of the approach. Moreover, a vibration harvester with the power converter proposed has been tested in real conditions in a wind turbine.</p></div>","PeriodicalId":704,"journal":{"name":"Micro and Nano Systems Letters","volume":"13 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://mnsl-journal.springeropen.com/counter/pdf/10.1186/s40486-025-00229-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145170545","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}
Han-Jung Kim, Junhee Kim, Jeongmin Park, Seyong Park, Sang-Keun Sung, Suhan Lee, Yohan Ko, Seung Woo Lee, Sung-Jin An, Yoonkap Kim
{"title":"All inkjet-printed flexible see-through heaters based on silver mesh pattern","authors":"Han-Jung Kim, Junhee Kim, Jeongmin Park, Seyong Park, Sang-Keun Sung, Suhan Lee, Yohan Ko, Seung Woo Lee, Sung-Jin An, Yoonkap Kim","doi":"10.1186/s40486-025-00227-3","DOIUrl":"10.1186/s40486-025-00227-3","url":null,"abstract":"<div><p>Heaters fabricated via printing conductive ink or paste on various flexible substrates have been extensively investigated. However, flexible/wearable heaters wherein all the functional structures (heater substrate, heating element, and cover layer) are fabricated via printing have not been reported. In this study, fully printed see-through conductors are fabricated using conductive Ag ink and dielectric ink and their potential for use as wearable see-through heaters is demonstrated. The relationship between the heater performance and the resistance of a printed Ag micromesh structure (which serves as the heating element) is analyzed. In addition, three types of printed heaters are fabricated based on different embedding configurations (three-sides open, one-side open, and fully embedded) of the Ag mesh electrodes, and their mechanical flexibilities are compared. The flexible heater based on the fully embedded Ag mesh structures exhibits remarkable mechanical flexibility. The rapid thermal response and high reliability of the printed flexible heaters are confirmed through Joule heating performance analysis. These results indicate the excellent potential of the proposed inkjet printing technology for the development of all-printed optoelectronics.</p></div>","PeriodicalId":704,"journal":{"name":"Micro and Nano Systems Letters","volume":"13 1","pages":""},"PeriodicalIF":4.7,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://mnsl-journal.springeropen.com/counter/pdf/10.1186/s40486-025-00227-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144090941","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}