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Permanent URI for this communityhttps://hdl.handle.net/20.500.14288/2

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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.
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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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Continuous glycemic monitoring enabled by a Wi-Fi energy-harvesting wearable sweat-sensing patch
(Wiley, 2024) Çakır, Cengiz; Department of Mechanical Engineering; Mirlou, Fariborz; Abbasiasl, Taher; Jahangiri, Hadi; Akhtar, Muhammad Junaid; Beker, Levent; İstif, Emin; Department of Mechanical Engineering; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Graduate School of Sciences and Engineering; College of Engineering
Continuous monitoring of multiple physiological parameters, such as glucose levels, temperature, and heart rate variability (HRV) is crucial for effective diabetes management and mitigating the risks associated with hypoglycemic events. These events often occur without apparent symptoms, posing a challenge for diabetic patients in managing their condition. Therefore, a non-invasive wearable device capable of continuously measuring multiple body signals to predict hypoglycemic events would be highly beneficial. In this study, a wearable patch that continuously measures glucose, temperature, and HRV is presented. The device uses a novel power harvesting system to convert radiofrequency (RF) signals with the frequency of 2.45 GHz to direct current (DC) signals to extend the battery life for further continuous monitoring. The patch is small and has a conformal structure that can easily fit onto different body parts. The screen-printed glucose sensor demonstrates a sensitivity of 10.3 nA cm-2 mu M-1, a limit of detection (LOD) of 8.9 mu M, and a limit of quantification (LOQ) of 27 mu M. The device employs a photoplethysmography (PPG) module with a peak-finding algorithm to calculate the HRV values. In vivo experiments demonstrate the validation of the device's proper operation in glucose, HRV, and temperature measurement. This study introduces a wearable patch for diabetes management, employing a unique Wi-Fi energy harvesting system for extended battery life. The device's conformal structure enables effortless placement on the body, providing continuous monitoring of glucose, HRV, and temperature. The platform presents a non-invasive physiological monitoring approach that enhances diabetes care by offering real-time data in a compact and efficient design.
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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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Paper integrated microfluidic contact lens for colorimetric glucose detection
(Royal Soc Chemistry, 2024) İstif, Emin; Department of Mechanical Engineering; İşgör, Pelin Kübra; Abbasiasl, Taher; Das, Ritu; Yener, Umut Can; Beker, Levent; Department of Mechanical Engineering; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Graduate School of Sciences and Engineering; College of Engineering
Contact lenses offer a simple, cost-effective, and non-invasive method for in situ real-time analysis of various biomarkers. Electro-chemical sensors are integrated into contact lenses for analysis of various biomarkers. However, they suffer from rigid electronic components and connections, leading to eye irritation and biomarker concentration deviation. Here, a flexible and microfluidic integrated paper-based contact lens for colorimetric analysis of glucose was implemented. Facilitating a three-dimensional (3D) printer for lens fabrication eliminates cumbersome cleanroom processes and provides a simple, batch compatible process. Due to the capillary force of the filter paper, the sample was routed to detection chambers inside microchannels, and it allowed further colorimetric detection. The paper-embedded microfluidic contact lens successfully detects glucose down to 2 mM within ∼10 s. The small dimension of the microfluidic system enables detection of glucose levels as low as 5 μl. The results show the potential of the presented approach to analyze glucose concentration in a rapid manner. It is demonstrated that the fabricated contact lens can successfully detect glucose levels of diabetic patients.
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Photolithography-based microfabrication of biodegradable flexible and stretchable sensors
(Wiley-V C H Verlag Gmbh, 2023) İstif, Emin; N/A; N/A; Department of Mechanical Engineering; N/A; N/A; Department of Mechanical Engineering; Bathaei, Mohammad Javad; Singh, Rahul; Mirzajani, Hadi; Akhtar, Muhammad Junaid; Abbasiasl, Taher; Beker, Levent; PhD Student; PhD Student; Researcher; Master Student; PhD Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; N/A; N/A; 308798
Biodegradable sensors based on integrating conductive layers with polymeric materials in flexible and stretchable forms have been established. However, the lack of a generalized microfabrication method results in large-sized, low spatial density, and low device yield compared to the silicon-based devices manufactured via batch-compatible microfabrication processes. Here, a batch fabrication-compatible photolithography-based microfabrication approach for biodegradable and highly miniaturized essential sensor components is presented on flexible and stretchable substrates. Up to 1600 devices are fabricated within a 1 cm(2) footprint and then the functionality of various biodegradable passive electrical components, mechanical sensors, and chemical sensors is demonstrated on flexible and stretchable substrates. The results are highly repeatable and consistent, proving the proposed method's high device yield and high-density potential. This simple, innovative, and robust fabrication recipe allows complete freedom over the applicability of various biodegradable materials with different properties toward the unique application of interests. The process offers a route to utilize standard micro-fabrication procedures toward scalable fabrication of highly miniaturized flexible and stretchable transient sensors and electronics.