Introduction University Computer Engineering programs continue to be a popular draw for students. Still, since they are relatively new, their defining curricula continue to evolve. Traditional courses such as digital logic, and digital... more
Introduction University Computer Engineering programs continue to be a popular draw for students. Still, since they are relatively new, their defining curricula continue to evolve. Traditional courses such as digital logic, and digital design, microcontrollers, computer interfacing and computer architecture are mainstays, but there continues to be many holes to fill. Part of the problem is that Computer Engineering (CE) is still considered to be an interface between Electrical Engineering (EE) and Computer Science (CS). Electrical Engineering, where it is usually housed, embraces the notion that computer hardware is fundamental to the discipline while computer science views computer software as the defining entity. The truth is that both are correct and computer engineering students need to understand both disciplines equally well. At the same time, this understanding needs to go beyond simply knowing about EE and CS. Students must be able to apply the principles of high level syste...
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Abstract— This work presents the development of a fully functional prototype of a wearable smart shoe insole that can monitor arterial oxygen saturation (SpO2) levels at the foot of a diabetic patient using photoplethysmography (PPG)... more
Abstract— This work presents the development of a fully
functional prototype of a wearable smart shoe insole that can
monitor arterial oxygen saturation (SpO2) levels at the foot of a
diabetic patient using photoplethysmography (PPG) signals.
Continuous monitoring of SpO2 levels at foot in patients with
diabetic foot ulcer (DFU) can provide critical information on the
severity of the ulcer, the wound healing process, and alerting
clinicians for critical limb ischemia. The developed oximetry
system seamlessly integrates the Internet of things (IoT) via a
custom-developed Android mobile application, thus enabling “athome”
monitoring. Twenty healthy subjects were tested, and the
insole oximeter was able to successfully estimate SpO2 levels at the
toe. An average error of ≈ 2.6% was calculated for the
measured/estimated SpO2 levels at the subjects’ toe when
compared to a reference oximeter attached to the finger. Perfusion
Index (PI) - which represents the blood flow/supply in tissues - was
used as a method for validating the oximeter readings. It was
observed that fingers (index fingers) generally have larger PI
values when compared to the toe, while PI results of both
monitoring sites were in the acceptable range. In addition, a dataset
was formed for the twenty test subjects, and machine learning
(ML) techniques were applied to predict the SpO2 level and the site
of measurement (Finger or Toe), using multiple linear regression
and classification methods. The ML results show that AC
components of the PPG signals have a more significant
contribution to the SpO2 estimations when compared to the DC
components. In addition, KNN (K=1) classifier, was able to
successfully predict the monitoring sites, with a test accuracy of
96.86%.
functional prototype of a wearable smart shoe insole that can
monitor arterial oxygen saturation (SpO2) levels at the foot of a
diabetic patient using photoplethysmography (PPG) signals.
Continuous monitoring of SpO2 levels at foot in patients with
diabetic foot ulcer (DFU) can provide critical information on the
severity of the ulcer, the wound healing process, and alerting
clinicians for critical limb ischemia. The developed oximetry
system seamlessly integrates the Internet of things (IoT) via a
custom-developed Android mobile application, thus enabling “athome”
monitoring. Twenty healthy subjects were tested, and the
insole oximeter was able to successfully estimate SpO2 levels at the
toe. An average error of ≈ 2.6% was calculated for the
measured/estimated SpO2 levels at the subjects’ toe when
compared to a reference oximeter attached to the finger. Perfusion
Index (PI) - which represents the blood flow/supply in tissues - was
used as a method for validating the oximeter readings. It was
observed that fingers (index fingers) generally have larger PI
values when compared to the toe, while PI results of both
monitoring sites were in the acceptable range. In addition, a dataset
was formed for the twenty test subjects, and machine learning
(ML) techniques were applied to predict the SpO2 level and the site
of measurement (Finger or Toe), using multiple linear regression
and classification methods. The ML results show that AC
components of the PPG signals have a more significant
contribution to the SpO2 estimations when compared to the DC
components. In addition, KNN (K=1) classifier, was able to
successfully predict the monitoring sites, with a test accuracy of
96.86%.
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MXenes are an emerging family of two-dimensional (2D) materials which exhibits unique characteristics such as metal-like thermal and electrical conductivity, huge surface area, biocompatibility, low toxicity, excellent electrochemical... more
MXenes are an emerging family of two-dimensional (2D) materials which exhibits unique characteristics such as metal-like thermal and electrical conductivity, huge surface area, biocompatibility, low toxicity, excellent electrochemical performance, remarkable chemical stability, antibacterial activity, and hydrophilicity. Initially, MXene materials were synthesized by selectively etching metal layers from MAX phases, layered transition metal carbides, and carbonitrides with hydrofluoric acid. Multiple novel synthesis methods have since been developed for the creation of MXenes with improved surface chemistries using non-aqueous etchants, molten salts, fluoride salts, and various acid halogens. Due to the promising potential of MXenes, they have emerged as attractive 2D materials with applications in various fields such as energy storage, sensing, and biomedical. This review provides a comprehensive overview of MXenes and discusses the synthesis and properties of MXenes, including the...
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A fabric based porous polydimethylsiloxane (PDMS) pressure sensor was developed and the effect of curing temperature on the porosity as well as the sensitivity was investigated. Three different porous PDMS dielectric layers (D1, D2 and... more
A fabric based porous polydimethylsiloxane (PDMS) pressure sensor was developed and the effect of curing temperature on the porosity as well as the sensitivity was investigated. Three different porous PDMS dielectric layers (D1, D2 and D3) were prepared by curing a mixture of PDMS, sodium hydrogen bicarbonate (NaHCO3), and nitric acid (HNO3) at 110 $^{\circ}C$, 140$^{\circ}C$ and 170$^{\circ}C$, respectively. The top and bottom electrodes of the pressure sensor were fabricated by screen printing silver (Ag) on a thermoplastic polyurethane (TPU) film. The screen-printed Ag-TPU film was permanently attached to a fabric using heat lamination process. Three pressure sensors, PS1, PS2 and PS3 were assembled by sandwiching the porous dielectric layers D1, D2 and D3 between the top and bottom electrodes, respectively. An average pore size of $411 \mu \mathrm{m}, 496 \mu \mathrm{m}$, and $502 \mu \mathrm{m}$ was measured for D1, D2 and D3, respectively. A relative capacitance change of $\sim 100$%, $\sim$ 323%, and $\sim$ 485% was obtained for the pressure sensors PS1, PS2, PS3, respectively, for varying applied pressures ranging from 0 to 1000 kPa. The effect of curing temperatures on the thickness as well as the dielectric constant of the porous PDMS layer, which in turn changes the sensitivity of the pressure sensors, was investigated and is presented in this paper.
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A novel electroencephalography (EEG) sensor was developed for monitoring and recording the electrical activity of the brain. A sensing electrode were developed by 3D printing Formlabs 80A flexible resin and coated with silver epoxy as... more
A novel electroencephalography (EEG) sensor was developed for monitoring and recording the electrical activity of the brain. A sensing electrode were developed by 3D printing Formlabs 80A flexible resin and coated with silver epoxy as well as a silver spray paint to make the electrodes conductive. The conductivity of the sensors was measured at 7.70 E+03 S/m. The electrodes are flexible and conformable enough to be worn on the head for extended periods of time without causing strain to the user. The current sensing electrodes in the market are stiff and cause headaches after extended periods of testing. The 3D printed sensing electrodes generated similar signal quality when compared to commercial electrodes while providing a far higher level of comfort.
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A flexible nickel (Ni) based resistance temperature detector (RTD) was successfully fabricated for monitoring temperature in automobile and aerospace applications. The RTD was developed by screen printing Ni based ink on a flexible... more
A flexible nickel (Ni) based resistance temperature detector (RTD) was successfully fabricated for monitoring temperature in automobile and aerospace applications. The RTD was developed by screen printing Ni based ink on a flexible ceramic platform. The ability of the RTD to monitor temperatures varying from 25°C to 200°C, in steps of 25°C was investigated. The results of the RTD demonstrated a linear response with resistive changes as high as 47.1% at 200 °C, when compared to its base resistance (20.2 kΩ) at 25 °C. A temperature coefficient of resistance (TCR) of 0.3%/°C, with a correlation coefficient of 0.9994 was calculated for the RTD. The response of the screen printed RTD is analyzed and presented in this paper.
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Surface acoustic waves (SAWs) are electro-mechanical waves that form on the surface of piezoelectric crystals. Because they are easy to construct and operate, SAW devices have proven to be versatile and powerful platforms for either... more
Surface acoustic waves (SAWs) are electro-mechanical waves that form on the surface of piezoelectric crystals. Because they are easy to construct and operate, SAW devices have proven to be versatile and powerful platforms for either direct chemical sensing or for upstream microfluidic processing and sample preparation. This review summarizes recent advances in the development of SAW devices for chemical sensing and analysis. The use of SAW techniques for chemical detection in both gaseous and liquid media is discussed, as well as recent fabrication advances that are pointing the way for the next generation of SAW sensors. Similarly, applications and progress in using SAW devices as microfluidic platforms are covered, ranging from atomization and mixing to new approaches to lysing and cell adhesion studies. Finally, potential new directions and perspectives of the field as it moves forward are offered, with a specific focus on potential strategies for making SAW technologies for bioa...
A first-principles study was successfully employed to investigate the impact of different ratios of functional groups such as fluorine (-F), oxygen (-O), and hydroxyl (-OH) on ammonia (NH3) sensing of titanium carbide Mxene. Density... more
A first-principles study was successfully employed to investigate the impact of different ratios of functional groups such as fluorine (-F), oxygen (-O), and hydroxyl (-OH) on ammonia (NH3) sensing of titanium carbide Mxene. Density functional theory (DFT) calculations were performed for studying the adsorption energy (Eads) and charge transfer (CT) between different gases (NH3, CO2, NO, H2S and SO2) and TbC2T x material with a high ratio of fluorine surface functional groups, TbC2(OH)o.44Fo.ssO0.66. DFT calculations showed more sensitivity to NH3, with the highest CT (0.098 e) and the lowest Eads (-0.36 eV) among the mentioned gases. The adsorption of NH3 on TbC2TxMXene with a high and low ratios of fluorine surface functional groups, TbC2(OH)o.44Fo.ssOO.66 (Substrate 1) and TbC2(OH)o.66Fo.2201.11 (Substrate 2) respectively, resulted in adsorption energies of −0.36 eV and −0.49 eV, revealing a stronger adsorption of NH3 on Substrate 2 with low ratios of fluorine. In addition, the isosurfaces representation of charge difference illustrated that fluorine atoms have smaller charge transfer than oxygen atoms when interacting with NH3 molecules. The Bader charge difference for the closest oxygen and fluorine atoms to NH3 molecule showed that oxygen atoms have 60% to 180% larger Bader charge difference, when compared to fluorine atoms, supporting that TbC2T x sensor with a lower ratio of fluorine surface termination has a stronger interaction with NH3 gas molecules.
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Graphene derivatives are promising nanomaterials for the development of various flexible electronic devices. In this work, a flexible temperature sensor based on fluorinated graphene (FG) was developed, using screen printing and... more
Graphene derivatives are promising nanomaterials for the development of various flexible electronic devices. In this work, a flexible temperature sensor based on fluorinated graphene (FG) was developed, using screen printing and drop-casting processes. Interdigitated electrodes (IDEs) were fabricated by the deposition of silver (Ag) ink on the polyimide substrate, using the screen printing process, and the FG sensing layer was formed by drop-casting of FG suspension on the IDEs. The resistive response of the temperature sensor towards temperatures varying from 10 °C to 80 °C, in steps of 10 °C, was investigated. The fabricated temperature sensor has a short response time (≤ 2 s) for different target temperature levels. A linear relationship between the relative resistance change (ΔR/Rb) and the temperature was observed, with a slope of -0.0013/°C and a correlation coefficient of 0.9964. The overall ΔR/Rb of the sensor was measured as -8.85% when the temperature changed from 20°C to 80 °C. The average temperature coefficient of resistance (TCR) of the temperature sensor was calculated as -0.132 ± 0.005 %/°C for the temperature range of 20 °C to 80 °C.
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A flexible microplasma discharge device (MDD) was successfully developed for inactivating a gram-negative pathogenic bacterium, Pseudomonas aeruginosa, under ambient operating conditions. The MDD was fabricated by sandwiching a flexible... more
A flexible microplasma discharge device (MDD) was successfully developed for inactivating a gram-negative pathogenic bacterium, Pseudomonas aeruginosa, under ambient operating conditions. The MDD was fabricated by sandwiching a flexible polyethylene terephthalate (PET) film as the dielectric layer, between copper based top and bottom electrodes. The top and bottom electrodes, which consists of copper tapes were patterned in a honeycomb and circular design respectively, using laser ablation. The efficacy of the MDD to inactivate P. aeruginosa cells in phosphate buffer saline (PBS) was investigated by testing the effect of varying treatment times ranging from 1 minute to 10 minutes. An 8log10 reduction in bacterial viability was achieved when the MDD was activated for 8.5 minutes at an input voltage of 10 V. The flexibility of the device was also tested by bending the MDD on surfaces with a radius of curvature of 25 mm and 50 mm. The calculated power density of the MDD in bent condition was compared with the power density in its unbent state. The performance of the MDD is analyzed and presented in this paper.
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This paper is focused on the development of a flexible and portable electrochemical system that can be used with a variety of two and three-electrode sensors while maintaining tremendous accuracy. Both the two-electrode and... more
This paper is focused on the development of a flexible and portable electrochemical system that can be used with a variety of two and three-electrode sensors while maintaining tremendous accuracy. Both the two-electrode and three-electrode sensors were created from a copper sheet using a laser etching process. The fabricated sensor was connected to a printed circuit board that was custom designed to measure the sensor response using different electrochemical techniques such as cyclic voltammogram as well as chronoamperogram towards varying concentrations of analytes. Once the sensor is calibrated, the system was able to detect the chemical concentrations and transmit the results wirelessly through Bluetooth. The system is powered with a 3.7V rechargeable lithium polymer battery which pulls ~2.8 mA resulting in a very low power consumption. Post analysis was performed on the custom smartphone application to view the analyte concentrations and record the results.
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A novel fluorinated graphene-based humidity sensor was successfully developed for humidity monitoring applications. The humidity sensor was fabricated by screen printing silver (Ag) interdigitated electrodes (IDEs) on a flexible polyimide... more
A novel fluorinated graphene-based humidity sensor was successfully developed for humidity monitoring applications. The humidity sensor was fabricated by screen printing silver (Ag) interdigitated electrodes (IDEs) on a flexible polyimide substrate. A fluorinated graphene powder, that was uniformly dispersed in isopropyl alcohol (IPA) using the ultra-sonication process, was drop casted on the IDEs as a humidity sensing layer. The resistive response of the fabricated humidity sensor towards varying relative humidity (RH) levels ranging from 20% RH to 70% RH, in steps of 10% RH, was investigated at a constant temperature of 24 °C. A maximum resistance change of 12.1% was observed when the humidity was changed from 20% RH to 70% RH, with a sensitivity of 0.24 %/%RH.
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A flexible microplasma discharge device (MDD) was successfully developed for sterilization of Pseudomonas aeruginosa, a gram-negative bacterium, using ambient air as the sterilizing agent. The MDD was fabricated by sandwiching a flexible... more
A flexible microplasma discharge device (MDD) was successfully developed for sterilization of Pseudomonas aeruginosa, a gram-negative bacterium, using ambient air as the sterilizing agent. The MDD was fabricated by sandwiching a flexible polyethylene terephthalate (PET) film, as the dielectric layer, between two layers of flexible copper tape, as top and bottom electrodes. The copper tape was patterned in a honeycomb and circular design for the top and bottom electrodes, respectively, using laser ablation. The sterilizing capability of the MDD was investigated by testing the effect of varying parameters including gap distance (1 mm to 9 mm) and treatment time (10 seconds to 300 seconds) for the sterilization of P. aeruginosa. A sterilization efficacy of 100% was achieved for gap distances ranging from 1 mm to 9 mm, when compared to the control. In addition, sterilization efficacies of 99.9% and 100% was achieved with a treatment time of 10 seconds and 60 seconds, respectively. Surface temperatures ranging from 26.2 °C to 72.8 °C were observed as the input voltage was increased from 4 V to 10.5 V, respectively. The performance of the MDD is analyzed and presented in this paper.
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Photonic curing has shown great promise in maintaining the integrity of flexible thin polymer substrates without structural degradation due to shrinkage, charring or decomposition during the sintering of printed functional ink films in... more
Photonic curing has shown great promise in maintaining the integrity of flexible thin polymer substrates without structural degradation due to shrinkage, charring or decomposition during the sintering of printed functional ink films in milliseconds at high temperatures. In this paper, single-step photonic curing of screen-printed nickel (Ni) electrodes is reported for sensor, interconnector and printed electronics applications. Solid bleached sulphate paperboard (SBS) and polyethylene terephthalate polymer (PET) substrates are employed to investigate the electrical performance, ink transfer and ink spreading that directly affect the fabrication of homogeneous ink films. Ni flake ink is selected, particularly since its effects on sintering and rheology have not yet been examined. The viscosity of Ni flake ink yields shear-thinning behavior that is distinct from that of screen printing. The porous SBS substrate is allowed approximately 20% less ink usage. With one-step photonic curing...
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ABSTRACT In this study, a guided shear horizontal mode surface acoustic wave (SH-SAW) sensor with 64° YX-LiNbO3 based piezoelectric substrate and gold (Au) interdigitated electrodes (IDE) was used for the detection of toxic heavy metal... more
ABSTRACT In this study, a guided shear horizontal mode surface acoustic wave (SH-SAW) sensor with 64° YX-LiNbO3 based piezoelectric substrate and gold (Au) interdigitated electrodes (IDE) was used for the detection of toxic heavy metal compounds. A flow cell, with a reservoir volume of 3 μl, which employs inlet and outlet valves for the microfluidic chamber and polydimethylsiloxane (PDMS) based microfluidic channels, was also designed and fabricated using an acrylic material. As the SAW propagates through the substrate between input and output IDEs, a change in the velocity of the wave due to the varying concentrations of the test analytes, causes a change in the resonant frequency. This frequency based response of the SAW sensor towards mercury sulfide (HgS) and lead sulfide (PbS) demonstrated the capability of the system to detect picomolar level concentrations. The response of the SAW sensor is analyzed and presented in this paper.
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A flexible wireless electrocardiogram (ECG) device was fabricated for monitoring physiological signals in wearable biomedical applications. The ECG device consists of dry electrodes and a readout module. The dry electrode was fabricated... more
A flexible wireless electrocardiogram (ECG) device was fabricated for monitoring physiological signals in wearable biomedical applications. The ECG device consists of dry electrodes and a readout module. The dry electrode was fabricated by depositing multi-walled carbon nanotube (MWCNT)/polydimethylsiloxane (PDMS) composite on a thermoplastic polyurethane (TPU) substrate with screen printed silver (Ag) layer. The readout module with wireless data transmission capability was designed and fabricated on a flexible polyimide substrate. The ECG device was attached to a fabric, and its performance was investigated by measuring the ECG signals and comparing the signals with the results of conventional wet Ag/AgCl ECG electrode ECG signals. It was observed that the device demonstrated equal performance in terms of signal intensity and correlation when compared to the conventional wet ECG electrodes. The methodology and results of the device are analyzed and presented in this paper.
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In this paper a flexible and stretchable strain gauge was screen printed and tested for micro-strain detection. The strain gauge was fabricated by screen printing carbon ink on thermoplastic polyurethane (TPU) substrate and then... more
In this paper a flexible and stretchable strain gauge was screen printed and tested for micro-strain detection. The strain gauge was fabricated by screen printing carbon ink on thermoplastic polyurethane (TPU) substrate and then encapsulated for protection from the effect of temperature and humidity. The strain gauge was bonded on to aluminium beams and the electromechanical response of the sensor was investigated by applying different loads. Resistance changes varying from 0.3 kΩ to 5.9 kΩ were observed as the loads were varied from 0.2 kg to 1.8 kg, with corresponding calculated gauge factors ranging from ~10 to ~20. The results demonstrate that the screen-printed strain gauge is highly sensitive and can be utilized for micro-strain (µƐ) detection. The response of the fabricated strain gauge as a function of resistance is investigated and presented in this paper.
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Wearable devices with integrated sensors for tracking human vitals are widely used for a variety of applications, including exercise, wellness, and health monitoring. Photoplethysmography (PPG) sensors use pulse oximetry to measure pulse... more
Wearable devices with integrated sensors for tracking human vitals are widely used for a variety of applications, including exercise, wellness, and health monitoring. Photoplethysmography (PPG) sensors use pulse oximetry to measure pulse rate, cardiac cycle, oxygen saturation, and blood flow by passing a light beam of variable wavelength through the skin and measuring its reflection. A multi-channel PPG wearable system was developed to include multiple nodes of pulse oximeters, each capable of using different wavelengths of light. The system uses sensor fusion along with machine learning model to perform feature extraction of relevant cardiovascular metrics across multiple pulse oximeters and predict saturated oxygen (SpO2). The developed model predicted SpO2 with a root mean square (RMSE) of 0.07 and accuracy of 99.5%. The wearable system was applied to the plant of the foot for vascular assessment. Wearable PPG systems capable of sensor fusion demonstrates a potential capability for continuous evaluation/monitoring of wounds and diseases associated with abnormal blood flow.
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A flexible carbon nanotube (CNT) based capacitive pressure sensor was developed for the detection of varying applied pressures. The sensor was successfully fabricated using the screen printing technique. Polydimethylsiloxane (PDMS) was... more
A flexible carbon nanotube (CNT) based capacitive pressure sensor was developed for the detection of varying applied pressures. The sensor was successfully fabricated using the screen printing technique. Polydimethylsiloxane (PDMS) was used as a dielectric layer and it was prepared using a PDMS pre-polymer and a curing agent mixed in a 10:1 ratio. The electrode was directly screen printed using conductive CNT ink onto the PDMS. The capability of the sensor to distinguish between varying applied pressures were investigated based on its capacitive response. It was observed that the CNT-based pressure sensor produced an 8.2% change in capacitance when compared to the base capacitance, for a maximum detectable pressure of 337 kPa. A 0.021% change in capacitance per kPa and a correlation coefficient of 0.9971 was also determined for the CNT-based pressure sensor. The capacitive response of the printed sensor demonstrated the feasibility of employing CNT-based electrodes for the development of efficient, flexible and cost-effective pressure sensors for sports, military, robotic, automotive and biomedical applications.
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A novel porous microstructured polydimethylsiloxane (PDMS) dielectric layer-based pressure sensor was developed for wearable applications. The porous micros-square structured (PMS-PDMS) dielectric layer was fabricated by using porous PDMS... more
A novel porous microstructured polydimethylsiloxane (PDMS) dielectric layer-based pressure sensor was developed for wearable applications. The porous micros-square structured (PMS-PDMS) dielectric layer was fabricated by using porous PDMS mixture and laser engraved acrylic master mold. The top and bottom electrodes of the pressure sensor were fabricated by screen printing silver (Ag) on a thermoplastic polyurethane (TPU) film, which was attached to a stretchable fabric using heat-lamination process. The PMS dielectric layer was sandwiched between the top and bottom electrodes using thin layer of adhesive PDMS. A relative capacitance change of 5% and 30% with a sensitivity of 4.98% kPa-1 and 2.53% kPa-1 was obtained for varying applied pressures ranging from 0 to 1 kPa, and 1 to 100 kPa, respectively.
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A flexible microplasma discharge device (MDD) was successfully fabricated for inactivating spore forming bacteria such as Bacillus subtilis. The device was operated under ambient conditions using ambient air as the inactivating agent. A... more
A flexible microplasma discharge device (MDD) was successfully fabricated for inactivating spore forming bacteria such as Bacillus subtilis. The device was operated under ambient conditions using ambient air as the inactivating agent. A flexible polyethylene terephthalate (PET) film was employed as the dielectric layer and sandwiched between layers of flexible copper tape. The top and bottom electrodes were laser ablated in a honeycomb and circular pattern, respectively. The efficacy of the MDD was analyzed by irradiating microplasma on to the surface of agar on a petri dish, that was inoculated with B. subtilis. One-and seven-days old culture of B. subtilis were used to investigate the effectiveness of MDD for varying treatment time. It was observed that the device was able to inactivate both one- and seven-days old culture of B subtilis from only one second of exposure time and achieved 4log10 reduction. The performance of the MDD towards vegetative and sporulated cells of B. subtilis are analyzed and presented in this paper.
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This paper is focused on the design and fabrication of a fully functional handheld and portable electrochemical analyzer for flexible hybrid electronics applications. A three-electrode sensor was fabricated from copper tape using laser... more
This paper is focused on the design and fabrication of a fully functional handheld and portable electrochemical analyzer for flexible hybrid electronics applications. A three-electrode sensor was fabricated from copper tape using laser etching process. The sensor was connected to a custom designed and programmed printed circuit board to measure the sensor response through electrochemical techniques for a large variation of chemical ion concentrations. The electronic circuit can perform cyclic voltammogram and chronoamperogram tests. After calibration, the measurements can be wirelessly transmitted to a smartphone and enables the user to view post analysis results including the analyte concentrations. The system is power efficient running off a 3.7V lithium polymer battery pulling ~2.8 mA.
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Fully printed, functionalized multi-walled carbon nanotube (FMWCNT)/hydroxyethyl cellulose (HEC) composite-based humidity sensor.
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A novel pulsometer was successfully developed using microelectromechanical systems (MEMS) based silicon-on-glass (SOG) technology for biomedical applications. The sensor was modelled and simulated in COMSOL Multiphysics® for pressures... more
A novel pulsometer was successfully developed using microelectromechanical systems (MEMS) based silicon-on-glass (SOG) technology for biomedical applications. The sensor was modelled and simulated in COMSOL Multiphysics® for pressures ranging from 0 to 40 mmHg. The capability of the fabricated pulsometer to detect movements in x and z-axis directions was investigated. The simulation results demonstrated displacement changes as high as of 98% and 36% in the x and z-axis directions, respectively for 40 mmHg, which correspond to typical radial blood pressure (rBP) on the wrist. In addition, an average capacitance change of 1 nF was experimentally obtained in the x-axis direction, from −5 V to 5 V. The response of the pulsometer is analyzed and presented in this paper.
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In this study, a microplasma discharge device (MDD) was modelled and simulated for sterilization applications. The MDD was modelled with copper and dielectric based electrodes on flexible polyethylene terephthalate substrate. COMSOL... more
In this study, a microplasma discharge device (MDD) was modelled and simulated for sterilization applications. The MDD was modelled with copper and dielectric based electrodes on flexible polyethylene terephthalate substrate. COMSOL Multiphysics® simulation performed on the MDD model demonstrated varying electron density and electric field distribution for AC terminal voltages ranging from 500 V to 8000 V. A variation of 14% and 54% was also observed for electron density and mobility, respectively when the temperature was increased from 240 K to 360 K, at constant pressure of 1 atm. In addition, a variation of 90% and 78% was observed for electron density and mobility, respectively when the pressure was increased from 0.3 atm to 1.3 atm, at constant room temperature of 295 K. The response of the MDD is analysed and presented in this paper.
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An electrochemical sensor was fabricated on a flexible polyethylene terephthalate (PET) substrate for the detection of cadmium sulfide (CdS), a heavy metal compound. The sensor consists of a working and reference electrode that were... more
An electrochemical sensor was fabricated on a flexible polyethylene terephthalate (PET) substrate for the detection of cadmium sulfide (CdS), a heavy metal compound. The sensor consists of a working and reference electrode that were gravure printed using silver (Ag) ink on the PET substrate. The performance of the sensor was investigated by measuring electrical impedance spectroscopy (EIS) for varying concentrations of the CdS. From the EIS based response, an impedance change of 11 ± 1%, 23 ± 1%, 34 ± 2% and 50 ± 3% was observed for the 1 pM, 1 nM, 1 µM and 1 mM concentrations of CdS, respectively when compared to de-ionized (DI) water, thus demonstrating the potential of employing gravure printed electrochemical sensors for heavy metal detection applications.
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In this paper – which was first presented at the 5th IEEE Conference on Sensors in Daegu, Republic of Korea, October 2006 – an improvement of the gas-sensing properties of the single-wall carbon nanotube (SWNT) by functionalizing its... more
In this paper – which was first presented at the 5th IEEE Conference on Sensors in Daegu, Republic of Korea, October 2006 – an improvement of the gas-sensing properties of the single-wall carbon nanotube (SWNT) by functionalizing its surface is reported upon. SWNTs were functionalized with sodium dodecyl sulphate (SDS), which improved the gas-sensing properties of the SWNTs. Solutions of SWNTs were deposited on the alumina substrate prepatterned with Pt contacts and heater to form the sensors. The morphology of the SWNT films were characterized by atomic force microscope (AFM) and transmission electron microscope (TEM) imaging, and their gas-sensing properties were studied using a voltamperometric technique. The sensors' sensitivity was tested in the presence of O3 (70–350 ppb), NO2 (0.1–5 ppm), CO (500 ppm), and NH3 (5 ppm) diluted in humid air (50 per cent relative humidity (RH)). The working temperature was varied in the range 20 °C–70 °C. The sensors showed an appreciable re...
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ABSTRACT A capacitive type humidity sensor (Inter Digitated Capacitor (IDC)) was successfully printed on a flexible Poly Ethylene Terephthalate (PET) substrate by means of rotogravure printing using Silver (Ag) nanoparticle based ink as... more
ABSTRACT A capacitive type humidity sensor (Inter Digitated Capacitor (IDC)) was successfully printed on a flexible Poly Ethylene Terephthalate (PET) substrate by means of rotogravure printing using Silver (Ag) nanoparticle based ink as metallization with dimensions of 200 μm electrode finger width and spacing. The fabricated device was spin coated with humidity sensitive hydrophilic polymer (Poly Methyl Methacrylate (PMMA)). The capacitive response of sensor towards Relative Humidity (% RH) was measured in the range of 40% RH to 80% RH; the maximum hysteresis is 8% at 60% RH. Details of the device, fabrication and response of the fabricated sensor towards humidity, hysteresis and stability were studied and are reported in this paper.
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This work presents the development of a fully functional prototype of a wearable smart shoe insole that can monitor arterial oxygen saturation (SpO2) levels at the foot of a diabetic patient using photoplethysmography (PPG) signals.... more
This work presents the development of a fully functional prototype of a wearable smart shoe insole that can monitor arterial oxygen saturation (SpO2) levels at the foot of a diabetic patient using photoplethysmography (PPG) signals. Continuous monitoring of SpO2 levels in diabetic foot ulcer (DFU) patients can provide critical information on the severity of the ulcer, the wound healing process, and the possible need for oxygenation of the wound bed. The developed oximetry system seamlessly integrates the Internet of Things (IoT) via a custom-developed Android mobile application, thus enabling "at-home" monitoring. Fifteen healthy subjects were tested, and the insole oximeter successfully estimated SpO2 levels at the toe. An average error of ≈ 2.8% was calculated for the measured/estimated SpO2 levels at the subjects’ toes compared to a reference oximeter attached to the finger. In people suffering from chronic DFU wounds, measuring and ensuring appropriate oxygen levels at the foot is critically important for healing the ulcer’s cells/tissues. The fabrication process of the system, details of the PPG tests, and analysis of the obtained results are presented and reported in this paper.