Browsing by Author "Daneshkhah, Ali"

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    Cross-Selectivity Enhancement of Poly(vinylidene fluoride-hexafluoropropylene)-Based Sensor Arrays for Detecting Acetone and Ethanol
    (MDPI, 2017-03-15) Daneshkhah, Ali; Shrestha, Sudhir; Siegel, Amanda; Varahramyan, Kody; Agarwal, Mangilal; Electrical and Computer Engineering, School of Engineering and Technology
    Two methods for cross-selectivity enhancement of porous poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP)/carbon black (CB) composite-based resistive sensors are provided. The sensors are tested with acetone and ethanol in the presence of humid air. Cross-selectivity is enhanced using two different methods to modify the basic response of the PVDF-HFP/CB sensing platform. In method I, the adsorption properties of PVDF-HFP/CB are altered by adding a polyethylene oxide (PEO) layer or by treating with infrared (IR). In method II, the effects of the interaction of acetone and ethanol are enhanced by adding diethylene carbonate (DEC) or PEO dispersed in DEC (PEO/DEC) to the film. The results suggest the approaches used in method I alter the composite ability to adsorb acetone and ethanol, while in method II, they alter the transduction characteristics of the composite. Using these approaches, sensor relative response to acetone was increased by 89% compared with the PVDF-HFP/CB untreated film, whereas sensor relative response to ethanol could be decreased by 57% or increased by 197%. Not only do these results demonstrate facile methods for increasing sensitivity of PVDF-HFP/CB film, used in parallel they demonstrate a roadmap for enhancing system cross-selectivity that can be applied to separate units on an array. Fabrication methods, experimental procedures and results are presented and discussed.
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    Cross-Selectivity Enhancement of Poly(vinylidene fluoride-hexafluoropropylene)-Based Sensor Arrays for Detecting Acetone and Ethanol
    (MDPI, 2017-03-15) Daneshkhah, Ali; Shrestha, Sudhir; Siegel, Amanda; Varahramyan, Kody; Agarwal, Mangilal; Mechanical Engineering, School of Engineering and Technology
    Two methods for cross-selectivity enhancement of porous poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP)/carbon black (CB) composite-based resistive sensors are provided. The sensors are tested with acetone and ethanol in the presence of humid air. Cross-selectivity is enhanced using two different methods to modify the basic response of the PVDF-HFP/CB sensing platform. In method I, the adsorption properties of PVDF-HFP/CB are altered by adding a polyethylene oxide (PEO) layer or by treating with infrared (IR). In method II, the effects of the interaction of acetone and ethanol are enhanced by adding diethylene carbonate (DEC) or PEO dispersed in DEC (PEO/DEC) to the film. The results suggest the approaches used in method I alter the composite ability to adsorb acetone and ethanol, while in method II, they alter the transduction characteristics of the composite. Using these approaches, sensor relative response to acetone was increased by 89% compared with the PVDF-HFP/CB untreated film, whereas sensor relative response to ethanol could be decreased by 57% or increased by 197%. Not only do these results demonstrate facile methods for increasing sensitivity of PVDF-HFP/CB film, used in parallel they demonstrate a roadmap for enhancing system cross-selectivity that can be applied to separate units on an array. Fabrication methods, experimental procedures and results are presented and discussed.
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    Low-Power ASIC Design for Multiple Integrated Sensors Applications
    (Office of the Vice Chancellor for Research, 2013-04-05) Jafarian, Hossein; Daneshkhah, Ali; Shrestha, Sudhir; Agarwal, Mangilal; Rizkalla, Maher; Varahramyan, Kody
    The aim of this work is to develop sensor integrated low-power chip for biomedical and other applications. Complementary metal-oxide-semiconductor (CMOS) technology in integrated circuit (IC) design has been applied to develop application specific integrated circuits (ASIC). An ASIC design that includes analog and digital sub-systems for various applications forming a system on chip (SoC) is presented. The analog sub-system drives multiple sensors, while the digital sub-system manages power, sensors, and signal output. A frequency of the pulse signals generated by the analog sub-system depends on the input voltage, which in-turn varies with sensor parameters. The frequency change of 750 MHz to 1 GHz was observed for input voltage variations of 1.2 to 2.2 V, with sensitivity of 10 mV. A separate temperature sensor included in the analog sub-system demonstrated frequency change of 830 to 440 MHz for temperature variations of ˗50°C to 100°C with resolution of 1°C. The output signal in digital sub-system is generated by counting the input pulses for each clock which has ‘on-state’ of only 3/16 seconds. This results in a significant reduction in the power consumption. This poster presents and discusses the system design and simulation results.
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    Model for Gold Nanoparticle Synthesis: Effect of pH and Reaction Time
    (American Chemical Society, 2021-06-24) Yazdani, Saeed; Daneshkhah, Ali; Diwate, Abolee; Patel, Hardi; Smith, Joshua; Reul, Olivia; Cheng, Ruihua; Izadian, Afshin; Hajrasouliha, Amir Reza; Physics, School of Science
    The synthesis of gold nanoparticles is dependent on both the concentration of trisodium citrate dihydrate and the time that it interacts with tetrachloroauric acid. A wide range of gold nanoparticles with various sizes and dispersity can be produced based on control variables, such as time of reaction and acid concentration, using a similar approach to that of the Turkevich model. In this model, the pH of the solution decreases slightly throughout the reaction (0.005 unit/min) due to the chemical interactions between trisodium citrate dihydrate and tetrachloroauric acid. Dicarboxy acetone is formed during citrate oxidization, resulting in gold nuclei formation over time. In addition, gold nanoparticle nucleation causes pH fluctuation over time based on gold nanoparticle sizes. An inverse correlation (coefficient of smaller than -0.97) was calculated between the pH and reaction time at different ratios of trisodium citrate dihydrate to tetrachloroauric acid. Regression analysis was used to develop a model for the prediction of the size of gold nanoparticles ranging from 18 to 38 nm based on the concentration of trisodium citrate dihydrate and the reaction time.
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    Urinary Volatile Terpenes Analyzed by Gas Chromatography–Mass Spectrometry to Monitor Breast Cancer Treatment Efficacy in Mice
    (ACS, 2020-03) Woollam, Mark; Teli, Meghana; Liu, Shengzhi; Daneshkhah, Ali; Siegel, Amanda P.; Yokota, Hiroki; Agarwal, Mangilal; Chemistry and Chemical Biology, School of Science
    Urinary volatile terpene (VT) levels are significantly altered with induced models of breast cancer in mice. The question arises whether VTs can detect the efficacy of antitumor treatments. BALB/c mice were injected with 4T1.2 murine tumor cells in the mammary pad or iliac artery to model localized breast cancer and induced bone metastasis. The effect of two dopaminergic antitumor agents was tested by conventional histology and altered VT levels. The headspace of urine specimens was analyzed by gas chromatography–mass spectrometry. In the localized model, the statistical significance (p < 0.05) was identified for 26% of VTs, and in the metastasis model, 19% of VTs. The authors discovered separate VT panels classifying localized/control [area under the curve (AUC) = 1.0] and metastasis/control (AUC = 0.98). Treatment samples were tested using these panels, which showed that mice treated with either agent were statistically significantly different from cancer samples, which is consistent with conventional analysis.