Erik Jonsson School of Engineering and Computer Science
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Browsing Erik Jonsson School of Engineering and Computer Science by Author "0000 0001 2765 4678 (Prasad, S)"
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Item Flexible Nanoporous Tunable Electrical Double Layer Biosensors for Sweat DiagnosticsMunje, Rujuta D.; Muthukumar, Sriram; Selvam, Anjan Panneer; Prasad, Shalini; 0000 0001 2765 4678 (Prasad, S); Munje, Rujuta D.; Selvam, Anjan Panneer; Prasad, ShaliniAn ultra-sensitive and highly specific electrical double layer (EDL) modulated biosensor, using nanoporous flexible substrates for wearable diagnostics is demonstrated with the detection of the stress biomarker cortisol in synthetic and human sweat. Zinc oxide thin film was used as active region in contact with the liquid i.e. synthetic and human sweat containing the biomolecules. Cortisol detection in sweat was accomplished by measuring and quantifying impedance changes due to modulation of the double layer capacitance within the electrical double layer through the application of a low orthogonally directed alternating current (AC) electric field. The EDL formed at the liquid-semiconductor interface was amplified in the presence of the nanoporous flexible substrate allowing for measuring the changes in the alternating current impedance signal due to the antibody-hormone interactions at diagnostically relevant concentrations. High sensitivity of detection of 1 pg/mL or 2.75 pmol cortisol in synthetic sweat and 1 ng/mL in human sweat is demonstrated with these novel biosensors. Specificity in synthetic sweat was demonstrated using a cytokine IL-1β. Cortisol detection in human sweat was demonstrated over a concentration range from 10–200 ng/mL.Item A Novel Approach for Electrical Tuning of Nano-Textured Zinc Oxide Surfaces for Ultra-Sensitive Troponin-t Detection(The Royal Society of Chemistry) Munje, Ruijuta D.; Jacobs, Michael; Muthukumar, S.; Quadri, Bilal; Shanmugam, Nandhinee Radha; Prasad, Shalini; 0000 0001 2765 4678 (Prasad, S); Munje, Ruijuta D.; Jacobs, Michael; Quadri, Bilal; Shanmugam, Nandhinee Radha; Prasad, ShaliniWe have developed a label-free, non-faradaic, electrochemical sensor for ultra-sensitive detection of a cardiac biomarker, troponin-T by utilizing the stoichiometric surface compositions of nanotextured zinc oxide (ZnO) thin films. In this study, we show how the performance of a nanotextured zinc oxide based non-faradaic biosensor is modulated by differences in the fabrication parameters of the metal oxide thin film as well as the choice of cross-linkers. Two cross-linking molecules, dithiobis succinimidyl propionate and 3-aminopropyl triethoxysilane, demonstrate significantly different binding chemistries with zinc oxide. The non-faradaic electrochemical behaviour of the sensor due to the two linkers is compared by analyzing the troponin-T dose response using electrochemical impedance spectroscopy (EIS). The sensor performance associated with both linkers is compared based on the dynamic range and limit of detection. The sensor utilizing zinc surface terminations demonstrated a wider dynamic range between the two linkers. This range extended from 26% to 54% in phosphate buffered saline and from 21% to 65% in human serum, for a concentration range from 10 fg mL⁻¹ to 1 ng mL⁻¹ of troponin-T. The limit of detection was found to be at 10 fg mL⁻¹ and has potential utility in the development of point-of-care (POC) diagnostics for cardiovascular diseases. Fluorescence quantification analysis was also performed to further validate the specificity of the linker binding to the ZnO films. An ultrasensitive troponin-T biosensor can be designed by leveraging the zinc termination based surface chemistry for selective protein immobilization.Item Screen Printed Graphene Oxide Textile Biosensor for Applications in Inexpensive and Wearable Point-Of-Exposure Detection of Influenza for At-Risk Populations(Electrochemical Society Inc.) Kinnamon, David S.; Krishnan, Siddharth; Brosler, Samantha; Sun, Evan; Prasad, Shalini; 0000 0001 2765 4678 (Prasad, S); 0000-0002-2404-3801 (Prasad, S); Kinnamon, David S.; Krishnan, Siddharth; Brosler, Samantha; Sun, Evan; Prasad, ShaliniA textile screen-printed biosensor was developed using silver conductive electrodes and graphene oxide transduction film built upon both nanoporous polyamide and consumer utility textiles for the detection of environmental exposure to influenza A virus. An affinity assay was constructed upon the graphene oxide layer to introduce influenza protein-specific antibodies to the sensor surface. Validation of fabrication reproducibility and stability, as well as affinity assay stability, was conducted using electrochemical impedance spectroscopy. The textile sensor was utilized for the detection of influenza A in biofluid analog buffer. Its linear dynamic range was from 10 ng/mL to 10 µg/mL with a limit of detection of 10 ng/mL, spanning both pre- and post-symptomatic ranges. The sensor can be integrated into common textiles and worn by at-risk populations to detect exposure to the virus before symptoms manifest. If integrated with Internet-of-Things reporting platforms, this sensor could have the ability to predict potential influenza outbreaks before broad symptoms manifest, reducing the physical and economic burden of the disease. © The Author(s) 2018.Item Simultaneous Lancet-Free Monitoring of Alcohol and Glucose from Low-Volumes of Perspired Human SweatBhide, Ashlesha; Muthukumar, Sriram; Saini, Amreek; Prasad, Shalini; 0000 0001 2765 4678 (Prasad, S); 0000-0002-2404-3801 (Prasad, S); Bhide, Ashlesha; Saini, Amreek; Prasad, ShaliniA lancet-free, label-free biosensor for simultaneous detection of sweat glucose and alcohol was demonstrated using zinc oxide thin films integrated into a nanoporous flexible electrode system. Sensing was achieved from perspired human sweat at low volumes (1-3μL), comparable to ambient conditions without external stimulation. Zinc oxide thin film electrodes were surface functionalized with alcohol oxidase enzyme and with glucose oxidase enzyme towards developing an affinity biosensor specific to the physiological relevant range of alcohol comprising of 0-2 drinks (0-50mg/dl) and physiologically relevant range of glucose ranging from hypo- to hyper-glycaemia (50- 130mg/dl) in perspired human sweat. Sensing was achieved by measuring impedance changes associated with alcohol and glucose binding onto the sensor interface using electrochemical impedance spectroscopy with a dynamic range from 0.01-200mg/dl and a limit of detection of 0.01mg/dl for alcohol in human sweat. Sensor calibration in synthetic sweat containing interferents (25-200mg/dl) and comparison using regression and Bland-Altman analysis of sweat sensor performance was done with BACtrack. Combinatorial detection of glucose and ethanol in perspired human sweat and comparison of sweat sensor performance with Accu-Chek blood glucose monitoring system that we expect would be relevant for pre-diabetics and diabetics for monitoring their glucose levels and alcohol consumption.Item A Wearable Biochemical Sensor for Monitoring Alcohol Consumption Lifestyle Through Ethyl Glucuronide (EtG) Detection in Human Sweat(Nature Publishing Group) Panneer Selvam, Anjan; Muthukumar, Sriram; Kamakoti, Vikramshankar; Prasad, Shalini; 0000 0001 2765 4678 (Prasad, S); 0000-0002-2404-3801 (Prasad, S); Panneer Selvam, Anjan; Kamakoti, Vikramshankar; Prasad, ShaliniWe demonstrate for the first time a wearable biochemical sensor for monitoring alcohol consumption through the detection and quantification of a metabolite of ethanol, ethyl glucuronide (EtG). We designed and fabricated two co-planar sensors with gold and zinc oxide as sensing electrodes. We also designed a LED based reporting for the presence of EtG in the human sweat samples. The sensor functions on affinity based immunoassay principles whereby monoclonal antibodies for EtG were immobilized on the electrodes using thiol based chemistry. Detection of EtG from human sweat was achieved through chemiresistive sensing mechanism. In this method, an AC voltage was applied across the two coplanar electrodes and the impedance across the sensor electrodes was measured and calibrated for physiologically relevant doses of EtG in human sweat. EtG detection over a dose concentration of 0.001-100 μg/L was demonstrated on both glass and polyimide substrates. Detection sensitivity was lower at 1 μg/L with gold electrodes as compared to ZnO, which had detection sensitivity of 0.001 μg/L. Based on the detection range the wearable sensor has the ability to detect alcohol consumption of up to 11 standard drinks in the US over a period of 4 to 9 hours.;