Bradley J. Bazuin

Gravure Printing of Conductive Inks on Glass Substrates for Applications in Printed Electronics

In graphics, gravure printing is the preferred method for printing high quality, fine dimension graphics using high-speed roll-to-roll or sheet fed presses. Gravure printing typically employs flexible and compressible substrates such as various papers and polymer films. In electronics, glass substrates are a common, if not preferred, substrate in many applications, particularly displays and photovoltaics. In combining printing with glass substrates, challenges exist in adapting contact-based printing methods such as gravure to the mechanical properties of the more rigid substrates. In this work, sheet-fed gravure printing has been successfully used to print silver-based conductive inks on glass substrates. Various features were designed and printed to evaluate conductive layers in terms of their printability and electrical performance. The independent variables include gravure cell dimensions, trace orientation with respect to printing direction and ink type. Results from this work provide an insight into the science of gravure printing on glass by correlating the independent variables to printed feature quality and electrical performance.

Gravure Printing of ITO Transparent Electrodes for Applications in Flexible Electronics

The possibility to directly pattern indium-tin-oxide (ITO) layers at ambient conditions by printing has many benefits. Printing, being an additive process, would greatly reduce the amount of energy, labor and material used by the current manufacturing processes to deposit and pattern ITO. In this work, gravure printability of ITO nanoparticles on polyethylene terephthalate (PET) was studied. A wide range of sheet resistivites and film thicknesses was obtained by varying the specifications of the gravure cells. From the regression analysis of the results, a good estimation of sheet resistivity of the printed films at different gravure cell volumes and aspect ratios (AR) was achieved. The films also showed transparency above 95% in the visible light region. In addition, printed ITO films were assessed for mechanical flexibility and the results compared to commercially available sputtered ITO films on PET. The electrical performance of printed ITO layers was not deteriorated with bending in contrast to the sputtered films. Therefore, printed ITO films can be of great benefit for applications in flexible electronics such as organic photovoltaics (OPV), liquid crystal displays (LCD), organic light-emitting diodes (OLED), touch screens, biosensors and utilization in the field of energy efficiency, especially in buildings.

Screen Printing of Multilayered Hybrid Printed Circuit Boards on Different Substrates

This paper reports on the successful fabrication of a multilayered hybrid printed circuit board (PCB) for applications in the consumer electronics products, medical technologies, and military equipment. The PCB was fabricated by screen-printing silver (Ag) flake ink, as metallization layer, and UV acrylic-based ink, as dielectric layer, on different substrates such as paper, polyethylene terephthalate, and glass. Traditional electronic components were attached onto the printed pads to create the multilayered hybrid PCB. The feasibility of the hybrid PCB was demonstrated by integrating an embedded microcontroller to drive an liquid-crystal display (160 × 100 pixels). In addition, the amount of the ink spreading after printing, the effect of bending on the printed lines, and the effect of the roughness of the substrates on the resistance of the printed lines was investigated. It was observed that the resistance of the lines increased by ≈1.8%, after 10000 cycles of bending, and the lowest resistance of 1.06 Ω was measured for the 600 μm printed lines on paper, which had a roughness of 0.175 μm. The advantage of fabricating PCBs on flexible substrates is the ability to fold and place the boards on nearly any platform or to conform to any irregular surface, whereas the additive properties of printing processes allow for a faster fabrication process, while simultaneously producing less material waste in comparison with the traditional subtractive processes. The results obtained show the promising potential of employing screen printing process for the fabrication of flexible and light-weight hybrid PCBs.

Generation of a four-wing chaotic attractor by two weakly-coupled lorenz systems

This paper presents a novel chaotic four-wing attractor generated by coupling two identical Lorenz systems. An analysis of the proposed system shows that its equilibria have certain symmetries with respect to specific coordinate planes and the eigenvalues of the associated Jacobian matrices exhibit the property of similarity. In analogy with the original Lorenz system, where the two wings of the butterfly attractor are located around the two equilibria with the unstable pair of complex-conjugate eigenvalues, this paper shows that the four wings of this new attractor are located around four equilibria with four unstable complex-conjugate eigenvalues. A generalization of the proposed system to realize an eight-wing attractor is also described.

A novel fully printed and flexible capacitive pressure sensor

A novel fully printed flexible capacitive pressure sensor was fabricated using conventional screen and gravure printing techniques. The sensor was successfully printed on a flexible polyethylene terephthalate (PET) substrate with silver (Ag) nanoparticle (NP) ink as the metallization layer and polydimethylsiloxane (PDMS) as the dielectric layer. The capacitive response of the sensor demonstrated a percentage change of 5 % and 40 % for minimum and maximum detectable compressive forces of 800 kPa and 18 MPa, respectively when compared to the base capacitance of 26 pF. At the minimum detectable pressure, the stability measurements resulted in a maximum variation of ± 0.15 % from the average capacitance value of 28 pf. The response of the printed device demonstrated the feasibility of employing traditional printing techniques for the fabrication of flexible pressure sensing devices.

3-D finite-element simulation model of SAW palladium thin film hydrogen sensor

A 3-dimensional finite element (3D-FE) simulation approach of a SAW palladium thin film hydrogen sensor using ANSYS was investigated. The effect of the palladium thin film on the propagation characteristics of the SAW was studied in the absence and presence of hydrogen. The center frequency of the SAW device was 100 MHz. The simulation results were obtained in terms of displacements and voltage at the output IDT. In addition, the depth profile of the particle movement was obtained in both x and y directions. The 3D representation of the wave propagation on the substrate with the palladium thin film is also shown. The results were obtained using the theoretical perturbation approach in ANSYS. This paper helps in understanding the behaviour of the SAW gas sensor without having to perform the actual fabrication.

Condition Based Maintenance for light trucks

Army ground vehicles often operate in extremely severe environmental and battlefield conditions. There are challenges for the reliability of the military ground vehicle fleet, which need to be addressed. Condition Based Maintenance (CBM) allows maintenance to be performed based on evidence of need provided by reliability modeling and/or other enabling technologies, thus reducing maintenance costs and increasing vehicle availability. The architecture of the Intelligent Vehicle Health Management System (IVHMS) for light trucks is presented. A fuzzy model is developed to diagnose the axle fatigue of the vehicle. The extraction of the fuzzy rules is based upon expert knowledge and a linear damage model. Training data will be used to modify the membership functions and the fuzzy If-Then rules to improve the quality of the fuzzy model for fault diagnostics. The improvement of the fuzzy model will be carried out using re-clustering operation and membership function optimization.

A novel flexographic printed strain gauge on paper platform

A novel flexible printed strain gauge was fabricated successfully on a flexible paper substrate using flexography printing process. Silver (Ag) ink was printed on the paper substrate as metallization layer. The performance of the printed device was investigated by subjecting the strain gauge to a 3-point bend test, with a displacement of 1 mm and 2 mm at 3 Hz operating frequency for 500 cycles. The electro-mechanical response of the strain gauge for the 1 mm displacement demonstrated an overall resistance change of 6.4 % and 6.5 % for the base resistance and bend resistance, respectively after 500 cycles of bending. Similarly an overall resistance change of 87.97 % and 28.8 % was observed for the base resistance and bend resistance, respectively after 500 cycles of bending for 2 mm displacement. The response of the fabricated strain gauge, as a function of electrical resistance, is analyzed and presented in this paper.

Design and simulation of SAW sensors for wireless sensing

This paper presents the design and frequency response simulation of surface acoustic wave (SAW) devices using MATLAB/spl trade/ used for passive wireless sensing of various measurands. Since SAW devices are widely used in radio frequency sensing applications, it is desirable to evaluate the device prior to fabrication especially in cases where the device material and dimensions have a major influence on the performance of the overall system. Three different types of SAW configurations namely the delay line, one-port resonator and two-port resonator was simulated in MATLAB/spl trade/. Both the equivalent circuit and the transmission matrices approaches have been used to simulate the frequency response of these SAW devices. The measured and simulated frequency responses are compared for a 433.92 MHz one-port resonator and it appears that the equivalent circuit approach is good for near resonance simulation whereas transmission matrix approach is a better choice if the response over a wide frequency range is required. Also, the effect of interdigital transducer (IDT) lead resistance, acoustic aperture and number of finger pairs on the performance of the system was studied and it was observed that an increase in the acoustic aperture and number of finger pairs increases the gain of the SAW device whereas an increase in the lead resistance lowers the gain. The results obtained are presented here along with the design parameters used in the simulations.

Fully printed and flexible piezoelectric based touch sensitive skin

A fully printed piezoelectric based touch sensitive skin has been successfully fabricated using screen printing technique. The device, consisting of a 4×4 array of printed sensors and interconnect lines, was fabricated on a flexible polyethylene terephthalate (PET) substrate, using silver (Ag) ink. Screen printed polyvinylidene fluoride (PVDF), as a piezoelectric layer, was sandwiched between the printed Ag top and bottom electrode metallization layers. The effective polarization of the printed piezoelectric PVDF layer was verified using capacitance-voltage analysis. Piezoelectric-voltage analysis demonstrated the capability of the device to generate voltage peaks as high as 10 V as well as the ability to turn on location based light-emitting diodes (LEDs). The response of the touch sensitive skin is analyzed and presented in this paper.