Memoon Sajid | Ghulam Ishaq khan institute of engineering sciences and technology (original) (raw)

Papers by Memoon Sajid

Relative humidity sensors are widely studied under the categories of both environmental and biose... more Relative humidity sensors are widely studied under the categories of both environmental and biosensors owing to their vast reaching applications. The research on humidity sensors is mainly divided into two concentration areas including novel material development and novel device structure. Another approach focuses on the development of printed sensors with performance comparable to the sensors fabricated via conventional techniques. The major challenges in the research on relative humidity sensors include the range of detection, sensitivity (especially at lower %RH), transient response time, and dependence on temperature. Temperature dependence is one of the least studied parameters in relative humidity sensor development. In this work, relative humidity sensors were fabricated using all-printed approaches that are also compatible with mass production, resulting in low cost and easy development. Laser-induced graphene (LIG)-based printed electrodes were used as the transducers, while the 2D MoS 2 and graphene nanocomposite was used as the active layer material with the built-in property of temperature independence. The exfoliation process of 2D MoS 2 was based on wet grinding, while graphene for the active layer was obtained by scratching the graphene grown on the polyimide (PI) surface via laser ablation. The resulting sensors showed an excellent output response for a full range of 0%RH to 100%RH, having no dependence on the surrounding temperature, and excellent response and recovery times of 4 and 2 s, respectively. The developed sensors can be confidently employed for a wide range of humidity sensing applications where the temperature of the surrounding environment is not constant.

Bulletin of Materials Science

2019 International Conference on Robotics and Automation in Industry (ICRAI)

Recently triboelectric nanogenerators (TENGs) have become a new and efficient way of power genera... more Recently triboelectric nanogenerators (TENGs) have become a new and efficient way of power generation for small devices. However, difficult and complex fabrication of these generators limits their usage. In this paper, we are presenting a simple and effective triboelectric nanogenerator made by using common household material such as paper, PET bottle, and pencil. The fabrication process is simple and cost-effective. The fabricated nanogenerator generated approximately an open-circuit voltage (Voc), short circuit current (Isc) and maximum power as 69.8 V, 79.6 μΑ, and 102.4 μw respectively. The energy produced by this nanogenerator is stored in capacitors which in turn can be used to power small electronic devices in a resource-limited environment.

2020 International Conference on UK-China Emerging Technologies (UCET), 2020

Among all other disease, diabetes is also one of the major health problems causing nearly 4.5 mil... more Among all other disease, diabetes is also one of the major health problems causing nearly 4.5 million deaths per year. According to the international diabetes federation 463 million people were suffering from the diabetes in 2019. It is estimated that this number will raise to 700 million by the year 2045. As, there is no cure for this disease even though level of glucose in the blood should be monitor inflexibly to get rid of more complications. So, monitoring of glucose level in the blood become inexorable need leading the researchers to manufacture a human friendly device which can accurately measure the blood glucose level. Conventionally invasive method is used worldwide to measure the blood glucose level from the blood sample. In this research work facile, low cost glucose characterization sensor is reported for the exploration of non-invasive glucose monitoring using biofluids. In this research work characterization of glucose concentrations from (1mM – 5mM) is performed successfully using facile, low cost glucose sensor. Platinum coated material is used for the sensor electrodes to minimize the cost of the sensor. Platinum based chronoamperometric glucose (PCAG) sensor is proposed in this research work. FR-4 substrate is used for the PCAG sensor. Low cost Portable potentiostat is fabricated to maintain potential across PCAG sensor electrodes. Characterization is performed for aqueous glucose solutions along with the glucose solutions in presence of impurities.

2016 IEEE International Symposium on Robotics and Intelligent Sensors (IRIS), 2016

Environmental monitoring and radiation detection in the vicinity of nuclear power plants is a tri... more Environmental monitoring and radiation detection in the vicinity of nuclear power plants is a tricky task and there is a potential radiation exposure hazard for the human beings and wildlife. To remotely monitor the environmental parameters like humidity, temperature, radiation, etc., the sensors were installed on a remotely controlled quad-copter drone. A GPS was also installed to determine the location and height of the drone for the particular parameters. An Arduino Yun based circuit interface was designed and was mounted on the drone as a multi-sensor standalone wireless node. Built-in Wi-Fi of the Yun board was used to transmit all the data to the base station. Android based application was developed to communicate with the node and display the data in real time along with logging it to device. Furthermore, a humidity and a temperature sensor were fabricated in through printed electronics methods and were also mounted on the drone with aim to replace commercial sensors. The aim of this research work was to build a system that can be used in future for monitoring of nuclear power plant vicinity and study the changes in environmental parameters in that region.

2018 9th International Conference on Mechanical and Aerospace Engineering (ICMAE), 2018

This work presents the fabrication and characterization of a highly sensitive all printed photo-d... more This work presents the fabrication and characterization of a highly sensitive all printed photo-detector based on a single layer active thin film. The active region consists of a composite of MEH:PPV and MoS2 quantum dots. The device was fabricated using reverse offset printing for the electrodes and hybrid surface acoustic wave Electrohydrodynamic atomization (SAW-EHDA) for thin film deposition. The device structure consists of interdigitated electrode pairs to increase the active exposure area and the sensitivity in return. The structure also has the advantage of having a single active layer without the top electrode making its fabrication a lot easier and simpler while improving the device robustness and stability. MoS2 quantum dots improve the device sensitivity towards exposure to ultraviolet (UV) region making the device an excellent candidate for commercial UV index sensors in wearable devices.

Thin films of p-type organic semiconducting nickel phthalocynanine (NiPc) and semitransparent Al ... more Thin films of p-type organic semiconducting nickel phthalocynanine (NiPc) and semitransparent Al were deposited in sequence by vacuum evaporation on a glass substrates with predeposited Ag source and drain electrodes. Organic field effect transistors were fabricated with metal (aluminum)–semiconductor (nickel phthalocyanine) Schottky junction. The effect of humidity on the NiPc based organic photo field effect transistors was investigated. It was found that in the relative humidity range of 45% to 93% RH, the resistance of the transistors decreased from 1.37 to 1.25 times depending on the thickness of the NiPc films, accordingly for 100 nm, 200 nm and 300 nm. The utilization of the NiPc based transistor as multi-functional or single-functional sensor is discussed.

3D Printing and Additive Manufacturing, 2018

Abstract A linear resistive temperature sensor has been 3D printed through fused deposition model... more Abstract A linear resistive temperature sensor has been 3D printed through fused deposition modeling using a conductive filament based on polylactic acid (PLA) and graphene nano rods (GNR) composite. The sensor is capable of measuring temperature variations based on the change in resistance of the printed pattern. As PLA is insensitive to and insoluble in water, the sensor can be used both in air and under water without any need of encapsulation. Graphene nanorods give the printed patterns a conductive property, while the PLA acts as a binder matrix. When the temperature rises, there is physical expansion of the polymer matrix at microscopic level that reduces the contact between the conductive GNRs and the resistance increases. On cooling down, the physical properties are retained and the resistance drops again. The sensors show excellent linearity and stability when tested both in air and under water up to 70°C. Beyond this temperature, the deformation in the polymer matrix is permanent and the resistan...

Journal of Materials Science: Materials in Electronics, 2018

Printed organic sensors are of significant importance owing to their simplicity, low cost, easy f... more Printed organic sensors are of significant importance owing to their simplicity, low cost, easy fabrication and solution processability. However, organic sensors often face the problem of performance degradation when exposed to ambient environment therefore, the effect of humidity needs to be studied for prolonging the lifetime of organic sensors. In this study, we propose atomically thin and highly reliable encapsulation layer on the surface of an organic functional material to enhance its lifetime as a temperature sensing unit. Our organic temperature sensor is based on a conductive and uniform IDT pattern deposited on a glass substrate through advanced printing technology of reverse offset. Thin film of PEDOT:PSS is used as the temperature sensitive functional layer deposited through electrohydrodynamic atomization while the organic thin film was encapsulated with aluminum oxide (Al 2 O 3) through spatial atmospheric atomic layer deposition system (SAALD). The temperature range of the developed sensors was from 25 to 90 °C with relative humidity reaching up to 75% RH. The obtained results exhibited that Al 2 O 3 encapsulation deposited through SAALD significantly enhanced the linearity, repeatability, endurance (50 cycles), retention (1 month) and lifetime of organic temperature sensor as compared to the non-encapsulated sensor. The performance degradation mechanism of non-encapsulated sensor due to humid environment has been discussed in detail. This study contributes an important step forward for preserving the performance and elongating the lifetime of organic electronic devices through a single atomically thin encapsulation.

International Journal of Precision Engineering and Manufacturing, 2018

Electrohydrodynamic (EHD) printing was employed here to fabricate conductive micro patterns for p... more Electrohydrodynamic (EHD) printing was employed here to fabricate conductive micro patterns for printed electronic devices. EHD printing offers fine pattern fabrication through additive manufacturing that has several advantages when compared to conventional lithographic techniques. One of the major advantages of additive manufacturing is its ability to print on already fabricated devices for the purpose of alteration or repair. However, printing of micro patterns on a fabricated MEMS device is a tedious task due to the electrostatically induced disturbances in cone jet and the formation of satellite droplets. In this study, a modified EHD printing technique called drop on demand (DOD) process was used to print silver micro patterns on a MEMS device with high accuracy. The focus here was to optimize the technique and parameters, and modify the system hardware to enable patterning on an untreated device surface. Parameters like supply voltage, waveform shape and frequency, pneumatic pressure, and ink flow rate have been studied and optimized to achieve repeatable and stable conductive patterns up to 3 µm. The modified EHD-DOD system also eliminates the problem of static surface charges by using low voltage thus enabling printing of highly repeatable sub-10 µm conductive patterns well suitable for MEMS repair.

Sensors and Actuators B: Chemical, 2018

In this work, a polymeric material poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:... more In this work, a polymeric material poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and a two dimensional material molybdenum disulfide (MoS2) 2D nanoflakes have been employed as the active layers of two separate transducers on a single substrate for the detection of relative humidity. The portion with MoS2 based active region showed high responsivity towards low humidity levels while PEDOT:PSS based portion responded well to high humidity levels. These two sensing portions were connected in a series combination to fabricate a single humidity sensing device capable to respond to a wide range of relative humidity with very high sensitivity. 2D MoS2 nanoflakes were obtained by aqueous exfoliation of pristine MoS2. The transducer electrode pairs were fabricated using reverse offset printing technique on a piezoelectric LiNbO3 substrate. The active thin film of MoS2 flakes was deposited by Electrohydrodynamic atomization (EHDA) while the thin film of PEDOT:PSS was deposited by SAW-EHDA hybrid system. The fabricated sensor is capable of sensing relative humidity with high sensitivity (50 kΩ/%RH or 800 Hz/%RH) in a wide range of 0% RH to 80% RH. The response and recovery times are also excellent with values of 0.5 s and 0.8 s respectively. This unique approach of combining multiple transducers in a single sensing device can lead to the development of high performance sensors and can solve the current limitations of single transducer based sensing devices.

Journal of Materials Chemistry C, 2018

A highly specific and sensitive linear humidity sensor has been fabricated using a dispersion of ... more A highly specific and sensitive linear humidity sensor has been fabricated using a dispersion of 2D hexagonal boron nitride (hBN) flakes in polyethylene oxide (PEO).

Sensors and Actuators A: Physical, 2018

 An elementary precipitation method was used to synthesize ZnO QDs.  ZnO QDs guiding layer faci... more  An elementary precipitation method was used to synthesize ZnO QDs.  ZnO QDs guiding layer facilitate immobilization of uricase and showed high sensitivity, and reproducibility of the biosensor.  A three electrode electrochemical biosensor was fabricated using screen printing method, successfully used for uric acid analysis.  Biosensor showed a wide linear range of detection 1-10 mM.  Covers the physiological range of uric acid present in urine sample.

Science and technology of advanced materials, 2018

Soft robots have received an increasing attention due to their advantages of high flexibility and... more Soft robots have received an increasing attention due to their advantages of high flexibility and safety for human operators but the fabrication is a challenge. Recently, 3D printing has been used as a key technology to fabricate soft robots because of high quality and printing multiple materials at the same time. Functional soft materials are particularly well suited for soft robotics due to a wide range of stimulants and sensitive demonstration of large deformations, high motion complexities and varied multi-functionalities. This review comprises a detailed survey of 3D printing in soft robotics. The development of key 3D printing technologies and new materials along with composites for soft robotic applications is investigated. A brief summary of 3D-printed soft devices suitable for medical to industrial applications is also included. The growing research on both 3D printing and soft robotics needs a summary of the major reported studies and the authors believe that this review a...

Scientific reports, Jan 19, 2017

Immunosensors are used to detect the presence of certain bio-reagents mostly targeted at the diag... more Immunosensors are used to detect the presence of certain bio-reagents mostly targeted at the diagnosis of a condition or a disease. Here, a general purpose electrical immunosensor has been fabricated for the quantitative detection of multiple bio-reagents through the formation of an antibody-antigen pair. The sensors were fabricated using all printing approaches. 2D transition metal dichalcogenide (TMDC) MoS2 thin film was deposited using Electrohydrodynamic atomization (EHDA) on top of an interdigitated transducer (IDT) electrode fabricated by reverse offset printing. The sensors were then treated with three different types of antibodies that were immobilized by physisorption into the highly porous multi-layered structure of MoS2 active layer. BSA was used as blocking agent to prevent non-specific absorption (NSA). The sensors were then employed for the targeted detection of the specific antigens including prostate specific antigen (PSA), mouse immunoglobulin-G (IgG), and nuclear f...

Journal of Materials Chemistry C, 2017

Organic–inorganic hybrid nanocomposites are an attractive choice for various electronic device ap... more Organic–inorganic hybrid nanocomposites are an attractive choice for various electronic device applications.

Scientific reports, Jan 19, 2015

Conventional surface acoustic wave - electrostatic deposition (SAW-ED) technology is struggling t... more Conventional surface acoustic wave - electrostatic deposition (SAW-ED) technology is struggling to compete with other thin film fabrication technologies because of its limitation in atomizing high density solutions or solutions with strong inter-particle bonding that requires very high frequency (100 MHz) and power. In this study, a hybrid surface acoustic wave - electrohydrodynamic atomization (SAW-EHDA) system has been introduced to overcome this problem by integrating EHDA with SAW to achieve the deposition of different types of conductive inks at lower frequency (19.8 MHZ) and power. Three materials, Poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV), Zinc Oxide (ZnO), and Poly(3, 4-ethylenedioxythiophene):Polystyrene Sulfonate ( PSS) have been successfully deposited as thin films through the hybrid SAW-EHDA. The films showed good morphological, chemical, electrical, and optical characteristics. To further evaluate the characteristics of deposited films, a hum...

Journal of Materials Science: Materials in Electronics, 2015

Large area organic light emitting diode (OLED) has been fabricated on flexible polyethylene terep... more Large area organic light emitting diode (OLED) has been fabricated on flexible polyethylene terephthalate (PET) substrate using electrohydrodynamics spray system with active area of 3 9 3 cm 2. This solution processing of organic inks and quantum dots is performed at room temperature and atmospheric pressure in a single step processing compatible with roll-to-roll processing system. The thin film characterizations are performed by SEM, TEM, spectroscopes and semiconductor device analyzer. CdSe/ZnS quantum dots are used as emissive layer while PEDOT:PSS and MEH-PPV are used as hole and electron transport layers. OLED produced red light at the wavelength of 634 nm. A life time of 1 h at 0.3 lx was achieved by the OLED device.

Functional Reverse Engineering of Machine Tools, 2019

Triboelectric nanogenerators (TENGs) have been introduced as a rational and effective way of powe... more Triboelectric nanogenerators (TENGs) have been introduced as a rational and effective way of powering the low consuming electronic devices and sensors. Mostly these nanogenerators are manufactured using costly materials and complex fabrication processes that restrict their usage especially in developing countries. In this paper, we have presented an inexpensive and facile TENG for powering the environmental sensor. Readily available and cost-effective materials were used for manufacturing TENG like paper, thread sealant PTFE tape, and pencil. The manufactured paper based TENG produced short circuit current and open circuit voltage of 110mumathrmA110\ \mu \mathrm{A}110mumathrmA and 234 V respectively. The maximum power density of 96.22mumathrmW/96.22\ \mu \mathrm{W} /96.22mumathrmW/ cm2 was achieved at 5 M Omega\OmegaOmega. The rectified signal from TENG was used to charge a capacitor array of 300mumathrmF300\ \mu \mathrm{F}300mumathrmF which was successively used to power the environmental sensor. Temperature and humidity can be measured by powering the environ...

Relative humidity sensors are widely studied under the categories of both environmental and biose... more Relative humidity sensors are widely studied under the categories of both environmental and biosensors owing to their vast reaching applications. The research on humidity sensors is mainly divided into two concentration areas including novel material development and novel device structure. Another approach focuses on the development of printed sensors with performance comparable to the sensors fabricated via conventional techniques. The major challenges in the research on relative humidity sensors include the range of detection, sensitivity (especially at lower %RH), transient response time, and dependence on temperature. Temperature dependence is one of the least studied parameters in relative humidity sensor development. In this work, relative humidity sensors were fabricated using all-printed approaches that are also compatible with mass production, resulting in low cost and easy development. Laser-induced graphene (LIG)-based printed electrodes were used as the transducers, while the 2D MoS 2 and graphene nanocomposite was used as the active layer material with the built-in property of temperature independence. The exfoliation process of 2D MoS 2 was based on wet grinding, while graphene for the active layer was obtained by scratching the graphene grown on the polyimide (PI) surface via laser ablation. The resulting sensors showed an excellent output response for a full range of 0%RH to 100%RH, having no dependence on the surrounding temperature, and excellent response and recovery times of 4 and 2 s, respectively. The developed sensors can be confidently employed for a wide range of humidity sensing applications where the temperature of the surrounding environment is not constant.

Bulletin of Materials Science

2019 International Conference on Robotics and Automation in Industry (ICRAI)

Recently triboelectric nanogenerators (TENGs) have become a new and efficient way of power genera... more Recently triboelectric nanogenerators (TENGs) have become a new and efficient way of power generation for small devices. However, difficult and complex fabrication of these generators limits their usage. In this paper, we are presenting a simple and effective triboelectric nanogenerator made by using common household material such as paper, PET bottle, and pencil. The fabrication process is simple and cost-effective. The fabricated nanogenerator generated approximately an open-circuit voltage (Voc), short circuit current (Isc) and maximum power as 69.8 V, 79.6 μΑ, and 102.4 μw respectively. The energy produced by this nanogenerator is stored in capacitors which in turn can be used to power small electronic devices in a resource-limited environment.

2020 International Conference on UK-China Emerging Technologies (UCET), 2020

Among all other disease, diabetes is also one of the major health problems causing nearly 4.5 mil... more Among all other disease, diabetes is also one of the major health problems causing nearly 4.5 million deaths per year. According to the international diabetes federation 463 million people were suffering from the diabetes in 2019. It is estimated that this number will raise to 700 million by the year 2045. As, there is no cure for this disease even though level of glucose in the blood should be monitor inflexibly to get rid of more complications. So, monitoring of glucose level in the blood become inexorable need leading the researchers to manufacture a human friendly device which can accurately measure the blood glucose level. Conventionally invasive method is used worldwide to measure the blood glucose level from the blood sample. In this research work facile, low cost glucose characterization sensor is reported for the exploration of non-invasive glucose monitoring using biofluids. In this research work characterization of glucose concentrations from (1mM – 5mM) is performed successfully using facile, low cost glucose sensor. Platinum coated material is used for the sensor electrodes to minimize the cost of the sensor. Platinum based chronoamperometric glucose (PCAG) sensor is proposed in this research work. FR-4 substrate is used for the PCAG sensor. Low cost Portable potentiostat is fabricated to maintain potential across PCAG sensor electrodes. Characterization is performed for aqueous glucose solutions along with the glucose solutions in presence of impurities.

2016 IEEE International Symposium on Robotics and Intelligent Sensors (IRIS), 2016

Environmental monitoring and radiation detection in the vicinity of nuclear power plants is a tri... more Environmental monitoring and radiation detection in the vicinity of nuclear power plants is a tricky task and there is a potential radiation exposure hazard for the human beings and wildlife. To remotely monitor the environmental parameters like humidity, temperature, radiation, etc., the sensors were installed on a remotely controlled quad-copter drone. A GPS was also installed to determine the location and height of the drone for the particular parameters. An Arduino Yun based circuit interface was designed and was mounted on the drone as a multi-sensor standalone wireless node. Built-in Wi-Fi of the Yun board was used to transmit all the data to the base station. Android based application was developed to communicate with the node and display the data in real time along with logging it to device. Furthermore, a humidity and a temperature sensor were fabricated in through printed electronics methods and were also mounted on the drone with aim to replace commercial sensors. The aim of this research work was to build a system that can be used in future for monitoring of nuclear power plant vicinity and study the changes in environmental parameters in that region.

2018 9th International Conference on Mechanical and Aerospace Engineering (ICMAE), 2018

This work presents the fabrication and characterization of a highly sensitive all printed photo-d... more This work presents the fabrication and characterization of a highly sensitive all printed photo-detector based on a single layer active thin film. The active region consists of a composite of MEH:PPV and MoS2 quantum dots. The device was fabricated using reverse offset printing for the electrodes and hybrid surface acoustic wave Electrohydrodynamic atomization (SAW-EHDA) for thin film deposition. The device structure consists of interdigitated electrode pairs to increase the active exposure area and the sensitivity in return. The structure also has the advantage of having a single active layer without the top electrode making its fabrication a lot easier and simpler while improving the device robustness and stability. MoS2 quantum dots improve the device sensitivity towards exposure to ultraviolet (UV) region making the device an excellent candidate for commercial UV index sensors in wearable devices.

Thin films of p-type organic semiconducting nickel phthalocynanine (NiPc) and semitransparent Al ... more Thin films of p-type organic semiconducting nickel phthalocynanine (NiPc) and semitransparent Al were deposited in sequence by vacuum evaporation on a glass substrates with predeposited Ag source and drain electrodes. Organic field effect transistors were fabricated with metal (aluminum)–semiconductor (nickel phthalocyanine) Schottky junction. The effect of humidity on the NiPc based organic photo field effect transistors was investigated. It was found that in the relative humidity range of 45% to 93% RH, the resistance of the transistors decreased from 1.37 to 1.25 times depending on the thickness of the NiPc films, accordingly for 100 nm, 200 nm and 300 nm. The utilization of the NiPc based transistor as multi-functional or single-functional sensor is discussed.

3D Printing and Additive Manufacturing, 2018

Abstract A linear resistive temperature sensor has been 3D printed through fused deposition model... more Abstract A linear resistive temperature sensor has been 3D printed through fused deposition modeling using a conductive filament based on polylactic acid (PLA) and graphene nano rods (GNR) composite. The sensor is capable of measuring temperature variations based on the change in resistance of the printed pattern. As PLA is insensitive to and insoluble in water, the sensor can be used both in air and under water without any need of encapsulation. Graphene nanorods give the printed patterns a conductive property, while the PLA acts as a binder matrix. When the temperature rises, there is physical expansion of the polymer matrix at microscopic level that reduces the contact between the conductive GNRs and the resistance increases. On cooling down, the physical properties are retained and the resistance drops again. The sensors show excellent linearity and stability when tested both in air and under water up to 70°C. Beyond this temperature, the deformation in the polymer matrix is permanent and the resistan...

Journal of Materials Science: Materials in Electronics, 2018

Printed organic sensors are of significant importance owing to their simplicity, low cost, easy f... more Printed organic sensors are of significant importance owing to their simplicity, low cost, easy fabrication and solution processability. However, organic sensors often face the problem of performance degradation when exposed to ambient environment therefore, the effect of humidity needs to be studied for prolonging the lifetime of organic sensors. In this study, we propose atomically thin and highly reliable encapsulation layer on the surface of an organic functional material to enhance its lifetime as a temperature sensing unit. Our organic temperature sensor is based on a conductive and uniform IDT pattern deposited on a glass substrate through advanced printing technology of reverse offset. Thin film of PEDOT:PSS is used as the temperature sensitive functional layer deposited through electrohydrodynamic atomization while the organic thin film was encapsulated with aluminum oxide (Al 2 O 3) through spatial atmospheric atomic layer deposition system (SAALD). The temperature range of the developed sensors was from 25 to 90 °C with relative humidity reaching up to 75% RH. The obtained results exhibited that Al 2 O 3 encapsulation deposited through SAALD significantly enhanced the linearity, repeatability, endurance (50 cycles), retention (1 month) and lifetime of organic temperature sensor as compared to the non-encapsulated sensor. The performance degradation mechanism of non-encapsulated sensor due to humid environment has been discussed in detail. This study contributes an important step forward for preserving the performance and elongating the lifetime of organic electronic devices through a single atomically thin encapsulation.

International Journal of Precision Engineering and Manufacturing, 2018

Electrohydrodynamic (EHD) printing was employed here to fabricate conductive micro patterns for p... more Electrohydrodynamic (EHD) printing was employed here to fabricate conductive micro patterns for printed electronic devices. EHD printing offers fine pattern fabrication through additive manufacturing that has several advantages when compared to conventional lithographic techniques. One of the major advantages of additive manufacturing is its ability to print on already fabricated devices for the purpose of alteration or repair. However, printing of micro patterns on a fabricated MEMS device is a tedious task due to the electrostatically induced disturbances in cone jet and the formation of satellite droplets. In this study, a modified EHD printing technique called drop on demand (DOD) process was used to print silver micro patterns on a MEMS device with high accuracy. The focus here was to optimize the technique and parameters, and modify the system hardware to enable patterning on an untreated device surface. Parameters like supply voltage, waveform shape and frequency, pneumatic pressure, and ink flow rate have been studied and optimized to achieve repeatable and stable conductive patterns up to 3 µm. The modified EHD-DOD system also eliminates the problem of static surface charges by using low voltage thus enabling printing of highly repeatable sub-10 µm conductive patterns well suitable for MEMS repair.

Sensors and Actuators B: Chemical, 2018

In this work, a polymeric material poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:... more In this work, a polymeric material poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and a two dimensional material molybdenum disulfide (MoS2) 2D nanoflakes have been employed as the active layers of two separate transducers on a single substrate for the detection of relative humidity. The portion with MoS2 based active region showed high responsivity towards low humidity levels while PEDOT:PSS based portion responded well to high humidity levels. These two sensing portions were connected in a series combination to fabricate a single humidity sensing device capable to respond to a wide range of relative humidity with very high sensitivity. 2D MoS2 nanoflakes were obtained by aqueous exfoliation of pristine MoS2. The transducer electrode pairs were fabricated using reverse offset printing technique on a piezoelectric LiNbO3 substrate. The active thin film of MoS2 flakes was deposited by Electrohydrodynamic atomization (EHDA) while the thin film of PEDOT:PSS was deposited by SAW-EHDA hybrid system. The fabricated sensor is capable of sensing relative humidity with high sensitivity (50 kΩ/%RH or 800 Hz/%RH) in a wide range of 0% RH to 80% RH. The response and recovery times are also excellent with values of 0.5 s and 0.8 s respectively. This unique approach of combining multiple transducers in a single sensing device can lead to the development of high performance sensors and can solve the current limitations of single transducer based sensing devices.

Journal of Materials Chemistry C, 2018

A highly specific and sensitive linear humidity sensor has been fabricated using a dispersion of ... more A highly specific and sensitive linear humidity sensor has been fabricated using a dispersion of 2D hexagonal boron nitride (hBN) flakes in polyethylene oxide (PEO).

Sensors and Actuators A: Physical, 2018

 An elementary precipitation method was used to synthesize ZnO QDs.  ZnO QDs guiding layer faci... more  An elementary precipitation method was used to synthesize ZnO QDs.  ZnO QDs guiding layer facilitate immobilization of uricase and showed high sensitivity, and reproducibility of the biosensor.  A three electrode electrochemical biosensor was fabricated using screen printing method, successfully used for uric acid analysis.  Biosensor showed a wide linear range of detection 1-10 mM.  Covers the physiological range of uric acid present in urine sample.

Science and technology of advanced materials, 2018

Soft robots have received an increasing attention due to their advantages of high flexibility and... more Soft robots have received an increasing attention due to their advantages of high flexibility and safety for human operators but the fabrication is a challenge. Recently, 3D printing has been used as a key technology to fabricate soft robots because of high quality and printing multiple materials at the same time. Functional soft materials are particularly well suited for soft robotics due to a wide range of stimulants and sensitive demonstration of large deformations, high motion complexities and varied multi-functionalities. This review comprises a detailed survey of 3D printing in soft robotics. The development of key 3D printing technologies and new materials along with composites for soft robotic applications is investigated. A brief summary of 3D-printed soft devices suitable for medical to industrial applications is also included. The growing research on both 3D printing and soft robotics needs a summary of the major reported studies and the authors believe that this review a...

Scientific reports, Jan 19, 2017

Immunosensors are used to detect the presence of certain bio-reagents mostly targeted at the diag... more Immunosensors are used to detect the presence of certain bio-reagents mostly targeted at the diagnosis of a condition or a disease. Here, a general purpose electrical immunosensor has been fabricated for the quantitative detection of multiple bio-reagents through the formation of an antibody-antigen pair. The sensors were fabricated using all printing approaches. 2D transition metal dichalcogenide (TMDC) MoS2 thin film was deposited using Electrohydrodynamic atomization (EHDA) on top of an interdigitated transducer (IDT) electrode fabricated by reverse offset printing. The sensors were then treated with three different types of antibodies that were immobilized by physisorption into the highly porous multi-layered structure of MoS2 active layer. BSA was used as blocking agent to prevent non-specific absorption (NSA). The sensors were then employed for the targeted detection of the specific antigens including prostate specific antigen (PSA), mouse immunoglobulin-G (IgG), and nuclear f...

Journal of Materials Chemistry C, 2017

Organic–inorganic hybrid nanocomposites are an attractive choice for various electronic device ap... more Organic–inorganic hybrid nanocomposites are an attractive choice for various electronic device applications.

Scientific reports, Jan 19, 2015

Conventional surface acoustic wave - electrostatic deposition (SAW-ED) technology is struggling t... more Conventional surface acoustic wave - electrostatic deposition (SAW-ED) technology is struggling to compete with other thin film fabrication technologies because of its limitation in atomizing high density solutions or solutions with strong inter-particle bonding that requires very high frequency (100 MHz) and power. In this study, a hybrid surface acoustic wave - electrohydrodynamic atomization (SAW-EHDA) system has been introduced to overcome this problem by integrating EHDA with SAW to achieve the deposition of different types of conductive inks at lower frequency (19.8 MHZ) and power. Three materials, Poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV), Zinc Oxide (ZnO), and Poly(3, 4-ethylenedioxythiophene):Polystyrene Sulfonate ( PSS) have been successfully deposited as thin films through the hybrid SAW-EHDA. The films showed good morphological, chemical, electrical, and optical characteristics. To further evaluate the characteristics of deposited films, a hum...

Journal of Materials Science: Materials in Electronics, 2015

Large area organic light emitting diode (OLED) has been fabricated on flexible polyethylene terep... more Large area organic light emitting diode (OLED) has been fabricated on flexible polyethylene terephthalate (PET) substrate using electrohydrodynamics spray system with active area of 3 9 3 cm 2. This solution processing of organic inks and quantum dots is performed at room temperature and atmospheric pressure in a single step processing compatible with roll-to-roll processing system. The thin film characterizations are performed by SEM, TEM, spectroscopes and semiconductor device analyzer. CdSe/ZnS quantum dots are used as emissive layer while PEDOT:PSS and MEH-PPV are used as hole and electron transport layers. OLED produced red light at the wavelength of 634 nm. A life time of 1 h at 0.3 lx was achieved by the OLED device.

Functional Reverse Engineering of Machine Tools, 2019

Triboelectric nanogenerators (TENGs) have been introduced as a rational and effective way of powe... more Triboelectric nanogenerators (TENGs) have been introduced as a rational and effective way of powering the low consuming electronic devices and sensors. Mostly these nanogenerators are manufactured using costly materials and complex fabrication processes that restrict their usage especially in developing countries. In this paper, we have presented an inexpensive and facile TENG for powering the environmental sensor. Readily available and cost-effective materials were used for manufacturing TENG like paper, thread sealant PTFE tape, and pencil. The manufactured paper based TENG produced short circuit current and open circuit voltage of 110mumathrmA110\ \mu \mathrm{A}110mumathrmA and 234 V respectively. The maximum power density of 96.22mumathrmW/96.22\ \mu \mathrm{W} /96.22mumathrmW/ cm2 was achieved at 5 M Omega\OmegaOmega. The rectified signal from TENG was used to charge a capacitor array of 300mumathrmF300\ \mu \mathrm{F}300mumathrmF which was successively used to power the environmental sensor. Temperature and humidity can be measured by powering the environ...

ICMAE 978-1-5386-7228-0/18 IEEE 2018, Budapest, Hungary

Oral Conference Presentation ICMEAE 2018, Nagoya, Japan

Oral Conference Presentation ICIET-339 2018, Istanbul, Turkey

Oral Conference Presentation ICETA 2017, Fukuoka, Japan

Invited Speaker at International Conference on Smart World (ICSW) 2017, China

Oral Conference Presentation IMRC 2017,Cancun, Mexico

Oral Conference Presentation ICFPE 2017, Jeju, Korea

Conference Poster Presentation Swiss-ePrint 2017, Basel, Switzerland

Conference Poster Presentation MNE 2014, Switzerland

Oral Conference Presentation IEEE IRIS 2016, Tokyo, Japan

Oral Conference Presentation ICRIET 2016, Osaka, Japan

Oral Conference Presentation ICRIET 2016, Osaka, Japan

Conference Poster Presentation TICEAS 2016, Singapore

Oral Conference Presentation International Workshop on Additive Manufacturing Technology Advancem... more Oral Conference Presentation
International Workshop on Additive Manufacturing Technology Advancement 2015, Jeju, Korea

Oral Conference Presentation PACRIM 2015, Korea

Oral Conference Presentation MCARE 2015, Jeju, Korea