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Dinesh Maddipatla

Bio: Dinesh Maddipatla is an academic researcher from Western Michigan University. The author has contributed to research in topics: Screen printing & Pressure sensor. The author has an hindex of 17, co-authored 81 publications receiving 831 citations.

Papers published on a yearly basis

Papers
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Journal ArticleDOI
TL;DR: In this article, a novel printed strain sensor based on metal-metal composite was developed for applications in the biomedical and civil infrastructural industries, which was fabricated by screen printing a silver nanowire (Ag NW)/silver (Ag flake composite on a flexible and stretchable thermoplastic polyurethane (TPU) substrate in two design configurations: straight line and wavy line.
Abstract: A novel printed strain sensor, based on metal-metal composite, was developed for applications in the biomedical and civil infrastructural industries. The sensor was fabricated by screen printing a silver nanowire (Ag NW)/silver (Ag) flake composite on a flexible and stretchable thermoplastic polyurethane (TPU) substrate in two design configurations: straight line and wavy line. The capability of the fabricated strain sensors was investigated by studying its electro-mechanical response towards varying elongations. Average resistance changes of 104.8%, 177.3% and 238.9%, over 100 cycles, and 46.8%, 141.4% and 243.6%, over 200 cycles, were obtained for the sensors with the straight and wavy line configurations at elongations of 1 mm, 2 mm and 3 mm, respectively. A sensitivity of 21% and 33%, in resistance change for every 1% strain, was calculated for the printed strain sensors with the straight and wavy line configurations, respectively. The results obtained thus demonstrate the feasibility of employing conventional addictive screen printing process for the development of strain sensors for applications that require a flexible and stretchable form factor.

100 citations

Journal ArticleDOI
TL;DR: In this article, a carbon nanotube (CNT) based negative temperature coefficient (NTC) thermistor was developed for temperature sensing applications, which was fabricated using additive print manufacturing processes on a flexible polyethylene terephthalate (PET) substrate.
Abstract: A fully printed carbon nanotube (CNT) based negative temperature coefficient (NTC) thermistor was developed for temperature sensing applications. The multi-layer NTC thermistor was fabricated using additive print manufacturing processes on a flexible polyethylene terephthalate (PET) substrate. Two silver (Ag) electrodes were printed using screen printing process. CNT based active layer was deposited by means of gravure printing. Organic and silver encapsulation layers were deposited using screen printing. The capability of the fabricated thermistor was investigated by measuring its response towards temperatures varying from −40 °C to 100 °C, in steps of 10 °C. As the temperature was increased from −40 °C to 100 °C, the resistive response of the thermistor decreased exponentially with an overall percentage change of 53% with the temperature coefficient of resistance (TCR) of −0.4%/°C. The stability of the printed thermistor towards relative humidity (RH) varying from 20% RH to 70% RH, in steps of 10% RH at two constant temperatures of 30 °C and 50 °C, was also studied. A maximum change of 0.34% and 0.1% was observed at 30 °C and 50 °C, respectively when compared to its base resistance at 20% RH. In addition, a response time of ≈300 ms and a recovery time of 4 s were measured for the printed thermistor with an accuracy of ± 0.5 °C.

97 citations

Journal ArticleDOI
TL;DR: In this paper, a novel porous polydimethylsiloxane (PDMS)-based capacitive pressure sensor was fabricated by optimizing the dielectric layer porosity for wide-range pressure sensing applications in the sports field.
Abstract: A novel porous polydimethylsiloxane (PDMS)-based capacitive pressure sensor was fabricated by optimizing the dielectric layer porosity for wide-range pressure sensing applications in the sports field. The pressure sensor consists of a porous PDMS dielectric layer and two fabric-based conductive electrodes. The porous PDMS dielectric layer was fabricated by introducing nitric acid (HNO3) into a mixture of PDMS and sodium hydrogen bicarbonate (NaHCO3) to facilitate the liberation of carbon dioxide (CO2) gas, which induces the creation of porous microstructures within the PDMS dielectric layer. Nine different pressure sensors (PS1, PS2,..., PS9) were fabricated in which the porosity (pore size, thickness) and dielectric constant of the PDMS dielectric layers were varied by changing the curing temperature, the mixing proportions of the HNO3/PDMS concentration, and the PDMS mixing ratio. The response of the fabricated pressure sensors was investigated for the applied pressures ranging from 0 to 1000 kPa. A relative capacitance change of ∼100, ∼323, and ∼485% was obtained by increasing the curing temperature from 110 to 140 to 170 °C, respectively. Similarly, a relative capacitance change of ∼170, ∼282, and ∼323% was obtained by increasing the HNO3/PDMS concentration from 10 to 15 to 20%, respectively. In addition, a relative capacitance change of ∼94, ∼323, and ∼460% was obtained by increasing the PDMS elastomer base/curing agent ratio from 5:1 to 10:1 to 15:1, respectively. PS9 exhibited the highest sensitivity over a wide pressure sensing range (low-pressure ranges (<50 Pa), 0.3 kPa-1; high-pressure ranges (0.2-1 MPa), 3.2 MPa-1). From the results, it was observed that the pressure sensors with dielectric layers prepared at relatively higher curing temperatures, higher HNO3 concentrations, and higher PDMS ratios resulted in increased porosity and provided the highest sensitivity. As an application demonstrator, a wearable fit cap was developed using an array of 16 pressure sensors for measuring and mapping the applied pressures on a player's head while wearing a helmet. The pressure mapping aids in observing and understanding the proper fit of the helmet in sports applications.

74 citations

Journal ArticleDOI
TL;DR: In this paper, a resistive flexible humidity sensor based on multi-walled carbon nanotubes (MWCNTs) was designed and fabricated, and the capability of the printed sensor, with heater, was investigated by subjecting it to relative humidity (RH) ranging from 10% to 90%.
Abstract: A resistive flexible humidity sensor based on multi-walled carbon nanotubes (MWCNTs) was designed and fabricated. Screen and gravure printing processes were used for monolithically fabricating the humidity sensor containing interdigitated electrodes (IDE), a sensing layer and a meandering conductive heater. An average thickness and surface roughness of $0.99~\mu \text{m}$ and $0.23~\mu \text{m}$ , respectively, was registered for the printed MWCNTs sensing layer. The capability of the printed sensor, with heater, was investigated by subjecting it to relative humidity (RH) ranging from 10% to 90%. The response demonstrated an overall resistance change of 55% when the sensor was subjected to 90% RH, when compared to 10% RH. A maximum hysteresis of 5.1%, at 70% RH, was calculated for the resistive response of the sensor. The printed sensors can be bend with radius of curvature of 1.5 inch with literally no effect.

71 citations

Proceedings ArticleDOI
13 Mar 2017
TL;DR: In this paper, a flexible carbon nanotube (CNT) based capacitive pressure sensor was developed for the detection of varying applied pressures using the screen printing technique, which was successfully fabricated using the CNT ink technique.
Abstract: 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.

68 citations


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01 Jan 2016
TL;DR: In this paper, a handbook of modern sensors physics designs and applications and applications are discussed. But instead of reading a good book with a cup of coffee in the afternoon, instead they juggled with some malicious bugs inside their laptop.
Abstract: Thank you for reading handbook of modern sensors physics designs and applications. As you may know, people have search hundreds times for their chosen readings like this handbook of modern sensors physics designs and applications, but end up in infectious downloads. Rather than reading a good book with a cup of coffee in the afternoon, instead they juggled with some malicious bugs inside their laptop.

249 citations

Journal ArticleDOI
TL;DR: The development of metal binder-free Ti3C2Tx MXene/graphene hybrid fibers by a scalable wet-spinning process, exhibiting excellent mechanical and electrical properties for applications in flexible wearable gas sensors, and envisage that these exciting features of 2D hybrid materials will provide a novel pathway for designing next-generation portable wearableGas sensors.
Abstract: Graphene-based fibers (GFs) have aroused enormous interest in portable, wearable electronics because of their excellent mechanical flexibility, electrical conductivity, and weavability, which make them advantageous for wearable electronic devices. Herein, we report the development of metal binder-free Ti3C2Tx MXene/graphene hybrid fibers by a scalable wet-spinning process. These hybrid fibers exhibit excellent mechanical and electrical properties for applications in flexible wearable gas sensors. The synergistic effects of electronic properties and gas-adsorption capabilities of MXene/graphene allow the created fibers to show high NH3 gas sensitivity at room temperature. The hybrid fibers exhibited significantly improved NH3 sensing response (ΔR/R0 = 6.77%) compared with individual MXene and graphene. The hybrid fibers also showed excellent mechanical flexibility with a minimal fluctuation of resistance of ±0.2% and low noise resistance even after bending over 2000 cycles, enabling gas sensing during deformation. Furthermore, flexible MXene/graphene hybrid fibers were woven into a lab coat, demonstrating their high potential for wearable devices. We envisage that these exciting features of 2D hybrid materials will provide a novel pathway for designing next-generation portable wearable gas sensors.

206 citations

Journal ArticleDOI
TL;DR: In this paper, the importance of smart wound dressings as an emerging strategy for wound care management and highlights different types of smart dressings for promoting the wound healing process is discussed.
Abstract: The universal increase in the number of patients with nonhealing skin wounds imposes a huge social and economic burden on the patients and healthcare systems. Although, the application of traditional wound dressings contributes to an effective wound healing outcome, yet, the complexity of the healing process remains a major health challenge. Recent advances in materials and fabrication technologies have led to the fabrication of dressings that provide proper conditions for effective wound healing. The 3D-printed wound dressings, biomolecule-loaded dressings, as well as smart and flexible bandages are among the recent alternatives that have been developed to accelerate wound healing. Additionally, the new generation of wound dressings contains a variety of microelectronic sensors for real-time monitoring of the wound environment and is able to apply required actions to support the healing progress. Moreover, advances in manufacturing flexible microelectronic sensors enable the development of the next generation of wound dressing substrates, known as electronic skin, for real-time monitoring of the whole physiochemical markers in the wound environment in a single platform. The current study reviews the importance of smart wound dressings as an emerging strategy for wound care management and highlights different types of smart dressings for promoting the wound healing process.

161 citations

Journal ArticleDOI
TL;DR: This study summarized and classified applications of different AM methods in manufacturing of sensors, briefly reviewed and compared AM techniques and categorized 3D-printed sensors based on their applications.
Abstract: Due to the technological advances, sensors have found a significant role in different aspects of human life. The sensors have been fabricated via various manufacturing processes. Recently, additive manufacturing (AM) has become a common method for fabrication of a wide range of engineering components in many industries. This manufacturing method, commonly known as three-dimensional (3D) printing is based on melting and solidification that leads to production of a component with high dimensional accuracy and smooth surface finish. As precision and elegant techniques are needed in manufacturing of the sensors, AM has been utilized in fabrication of these parts in the last few years. In this study, we summarized and classified applications of different AM methods in manufacturing of sensors. In this context, we briefly reviewed and compared AM techniques and categorized 3D-printed sensors based on their applications. Moreover, fabrication of sensors via AM is explained in details, challenges and future prospect of this manufacturing process are discussed. Investigations on the performed studies proved that higher printing resolution, faster speed and higher efficiency are needed to reach a remarkable advance in the production of 3D-printed sensors. The presented data can be utilized not only for comparison, improvement and optimization of fabrication processes, but also is beneficial for next research in production of highly sensitive sensors.

146 citations