Researcher:
İstif, Emin

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Emin

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İstif

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İstif, Emin

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2020 - 20227

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Researcher Of Publications: search.filters.isAuthorOfPublication.42c174e9-b4a9-4ee7-925c-33ea326c815c

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Now showing 1 - 7 of 7
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    Femtosecond laser ablation assisted nfc antenna fabrication for smart contact lenses
    (Wiley, 2022) N/A; Department of Mechanical Engineering; Department of Mechanical Engineering; N/A; N/A; N/A; N/A; Department of Mechanical Engineering; Mirzajani, Hadi; İstif, Emin; Abbasiasl, Taher; Mirlou, Fariborz; Özkahraman, Ecem Ezgi; Hasanreisoğlu, Murat; Beker, Levent; Researcher; Other; PhD Student; PhD Student; N/A; Faculty Member; Faculty Member; Department of Mechanical Engineering; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); n2STAR-Koç University Nanofabrication and Nanocharacterization Center for Scientifc and Technological Advanced Research; College of Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; N/A; School of Medicine; College of Engineering; N/A; N/A; N/A; N/A; N/A; 182001; 308798
    Smart contact lenses (SCLs) have drawn substantial interest for continuous health monitoring applications. Even though most of the reported works utilize near-field communication (NFC) or inductive coupling for wireless powering and data transmission, developing a scalable and rapid fabrication technique for annular ring antennas confined in a small contact lens area is still an unsolved challenge. Here, femtosecond laser ablation is employed for the first time as a simple, single-step, and highly precise fabrication technique for NFC antennas using conventional flexible printed circuit board materials. Antenna lines with depth and width of 9 and 35 mu m are achieved, respectively. The antenna with a footprint of 19.5 mm(2) is characterized in biological solution followed by aging, and bending tests, and a frequency deviation of less than %1 is recorded. A real-life application is demonstrated by fabricating an SCL embedded with the antenna, an NFC chip, and an electrochemical sensor for wireless monitoring of glucose in artificial tear solution by a smartphone. The device could successfully quantify biologically relevant glucose concentrations ranging from 0.2 to 1 mM with a limit-of-detection of 66 mu M. In addition, device response to interfering molecules is less than +/- 1 nA, and the spike-and-recovery test is successfully demonstrated.
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    A review of bioresorbable implantable medical devices: materials, fabrication, and implementation
    (Wiley, 2020) N/A; N/A; Department of Mechanical Engineering; Department of Mechanical Engineering; Singh, Rahul; Bathaei, Mohammad Javad; İstif, Emin; Beker, Levent; PhD Student; PhD Student; Researcher; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; 354990; 308798
    Implantable medical devices (IMDs) are designed to sense specific parameters or stimulate organs and have been actively used for treatment and diagnosis of various diseases. IMDs are used for long-term disease screening or treatments and cannot be considered for short-term applications since patients need to go through a surgery for retrieval of the IMD. Advances in bioresorbable materials has led to the development of transient IMDs that can be resorbed by bodily fluids and disappear after a certain period. These devices are designed to be implanted in the adjacent of the targeted tissue for predetermined times with the aim of measurement of pressure, strain, or temperature, while the bioelectronic devices stimulate certain tissues. They enable opportunities for monitoring and treatment of acute diseases. To realize such transient and miniaturized devices, researchers utilize a variety of materials, novel fabrication methods, and device design strategies. This review discusses potential bioresorbable materials for each component in an IMD followed by programmable degradation and safety standards. Then, common fabrication methods for bioresorbable materials are introduced, along with challenges. The final section provides representative examples of bioresorbable IMDs for various applications with an emphasis on materials, device functionality, and fabrication methods.
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    An ultra-compact and wireless tag for battery-free sweat glucose monitoring
    (Elsevier Advanced Technology, 2022) N/A; Department of Mechanical Engineering; N/A; N/A; Department of Mechanical Engineering; N/A; N/A; N/A; N/A; Department of Mechanical Engineering; Mirzajani, Hadi; Abbasiasl, Taher; Mirlou, Fariborz; İstif, Emin; Bathaei, Mohammad Javad; Dağ, Çağdaş; Deyneli, Oğuzhan; Dereli, Dilek Yazıcı; Beker, Levent; Researcher; PhD Student; PhD Student; Other; PhD Student; Faculty Member; Faculty Member; Faculty Member; Faculty Member; Department of Mechanical Engineering; Koç Üniversitesi İş Bankası Enfeksiyon Hastalıkları Uygulama ve Araştırma Merkezi (EHAM) / Koç University İşbank Center for Infectious Diseases (KU-IS CID); n2STAR-Koç University Nanofabrication and Nanocharacterization Center for Scientifc and Technological Advanced Research; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; N/A; School of Medicine; School of Medicine; College of Engineering; N/A; N/A; N/A; N/A; N/A; N/A; 171914; 179659; 308798
    Glucose monitoring before, during, and after exercise is essential for people with diabetes as exercise increases the risk of activity-induced hyper- and hypo-glycemic events. The situation is even more challenging for athletes with diabetes as they have impaired metabolic control compared to sedentary individuals. In this regard, a compact and noninvasive wearable glucose monitoring device that can be easily worn is critical to enabling glucose monitoring. This report presents an ultra-compact glucose tag with a footprint and weight of 1.2 cm(2) and 0.13 g, respectively, for sweat analysis. The device comprises a near field communication (NFC) chip, antenna, electrochemical sensor, and microfluidic channels implemented in different material layers. The device has a flexible and conformal structure and can be easily attached to different body parts. The battery-less operation of the device was enabled by NFC-based wireless power transmission and the compact antenna. Femtosecond laser ablation was employed to fabricate a highly compact and flexible NFC antenna. The proposed device demonstrated excellent operating characteristics with a limit of detection (LOD), limit of quantification (LOQ), and sensitivity of 24 mu M, 74 mu M, and 1.27 mu A cm(-2) mM(-1), respectively. The response of the proposed sensor in sweat glucose detection and quantification was validated by nuclear magnetic resonance spectroscopy (NMR). Also, the device's capability in attachment to the body, sweat collection, and glucose measurement was demonstrated through in vitro and in vivo experiments, and satisfactory results were obtained.
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    Powering smart contact lenses for continuous health monitoring: Recent advancements and future challenges
    (Elsevier Advanced Technology, 2022) N/A; Department of Mechanical Engineering; N/A; Department of Mechanical Engineering; N/A; Department of Mechanical Engineering; Mirzajani, Hadi; Mirlou, Fariborz; İstif, Emin; Singh, Rahul; Beker, Levent; Researcher; PhD Student; Other; PhD Student; Faculty Member; Department of Mechanical Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; N/A; 308798
    As the tear is noninvasively and continuously available, it has been turned into a convenient biological interface as a wearable medical device for out-of-hospital and self-monitoring applications. Recent progress in integrated circuits (ICs) and biosensors coupled with wireless data communication techniques have led to the implementation of smart contact lenses that can continuously sample tear fluid, analyze physiological conditions, and wirelessly transmit data to an electronic device such as smartphone, which can send data to relevant healthcare units. Continuous analyte monitoring is one of the significant characteristics of wearable biosensors. However, despite several advantages over other on-skin wearable medical devices, batteries cannot be incorporated on smart contact lenses for continuous electrical power supply due to the limited area. Herein, we review the progress of power delivery techniques of smart contact lenses for the first time. Different approaches, including wireless power transmission (WPT), biofuel cells, supercapacitors, flexible batteries, wired connections, and hybrid methods, are thoroughly discussed to understand the principles of self-sustainable contact lens biosensors comprehensively. Additionally, recent progress in contact lens biosensors is reviewed in detail, thereby providing the prospects for further developments of smart contact lenses as a common biosensing platform for various disease monitoring and diagnostic applications.
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    PublicationOpen Access
    Thiophene-based trimers for in vivo electronic functionalization of tissues
    (American Chemical Society (ACS), 2020) Mantione, Daniele; Dufil, Gwennael; Vallan, Lorenzo; Parker, Daniela; Brochon, Cyril; Cloutet, Eric; Hadziioannou, Georges; Berggren, Magnus; Stavrinidou, Eleni; Pavlopoulou, Eleni; Department of Mechanical Engineering; İstif, Emin; Faculty Member; Master Student; Department of Mechanical Engineering; College of Engineering
    Electronic materials that can self-organize in vivo and form functional components along the tissue of interest can result in a seamless integration of the bioelectronic interface. Previously, we presented in vivo polymerization of the conjugated oligomer ETE-S in plants, forming conductors along the plant structure. The EDOT-thiophene-EDOT trimer with a sulfonate side group polymerized due to the native enzymatic activity of the plant and integrated within the plant cell wall. Here, we present the synthesis of three different conjugated trimers based on thiophene and EDOT or purely EDOT trimers that are able to polymerize enzymatically in physiological pH in vitro as well as in vivo along the roots of living plants. We show that by modulating the backbone and the side chain, we can tune the electronic properties of the resulting polymers as well as their localization and penetration within the root. Our work paves the way for the rational design of electronic materials that can self-organize in vivo for spatially controlled electronic functionalization of living tissue.
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    PublicationOpen Access
    Thiophene-based trimers and their bioapplications: an overview
    (Multidisciplinary Digital Publishing Institute (MDPI), 2021) Vallan, L.; Gómez, I. J.; Alegret, N.; Mantione, Daniele; Department of Mechanical Engineering; İstif, Emin; Department of Mechanical Engineering; College of Engineering
    Certainly, the success of polythiophenes is due in the first place to their outstanding electronic properties and superior processability. Nevertheless, there are additional reasons that contribute to arouse the scientific interest around these materials. Among these, the large variety of chemical modifications that is possible to perform on the thiophene ring is a precious aspect. In particular, a turning point was marked by the diffusion of synthetic strategies for the preparation of terthiophenes: the vast richness of approaches today available for the easy customization of these structures allows the finetuning of their chemical, physical, and optical properties. Therefore, terthiophene derivatives have become an extremely versatile class of compounds both for direct application or for the preparation of electronic functional polymers. Moreover, their biocompatibility and ease of functionalization make them appealing for biology and medical research, as it testifies to the blossoming of studies in these fields in which they are involved. It is thus with the willingness to guide the reader through all the possibilities offered by these structures that this review elucidates the synthetic methods and describes the full chemical variety of terthiophenes and their derivatives. In the final part, an in-depth presentation of their numerous bioapplications intends to provide a complete picture of the state of the art.
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    PublicationOpen Access
    A wearable paper-integrated microfluidic device for sequential analysis of sweat based on capillary action
    (Royal Society of Chemistry (RSC), 2022) Koydemir, Hatice Ceylan; Department of Mechanical Engineering; Department of Electrical and Electronics Engineering; Beker, Levent; Abbasiasl, Taher; Mirlou, Fariborz; İstif, Emin; Faculty Member; Department of Mechanical Engineering; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; 308798; N/A; N/A; N/A
    Soft, skin-mounted microfluidic devices can collect microliter volumes of eccrine sweat and are capable of in situ real-time analysis of different biomarkers to assess physiological state and health. Chrono-analysis of sweat can be implemented to monitor temporal variations of biomarker concentrations over a certain period of interest. Conventional methods used to capture sweat or some of the newly developed microfluidic platforms for sweat collection and analysis are based on absorbent pads. They suffer from evaporation, leading to considerable deviations in the concentration of the biomarkers. Here, a paperintegrated microfluidic device is presented for sequential analysis of sweat that is easy to fabricate and does not include air exits for each reservoir, which reduces undesirable effects of sweat evaporation. Furthermore, the high capillary force of filter paper is leveraged to route the liquid into the chambers in a sequential fashion and allow further chemical analysis. The employed design of the paper-embedded microfluidic device successfully samples and analyzes artificial sweat sequentially for flow rates up to 5 ?L min?1 without showing any leakage. We demonstrated the performance of the device, employing colorimetric assays for chrono-analysis of glucose standard solutions at concentrations in the range of 10– 100 mM and pH of sweat during exercise. The results reveal the presented approach's functionality and potential to analyze the concentration of biomarkers over a certain period sequentially.