Marian Rebros

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.

Printed electrochemical based biosensors on flexible substrates

A flexible substrate electrochemical biosensor was successfully printed on a polyethylene terephthalate (PET) film with silver (Ag) electrodes using silver nanoparticle based ink. The electrochemical impedance spectroscopy (EIS) response of the printed sensor for detecting low concentrations of bio/chemical species revealed a very high sensitivity at pico molar (pM) concentration levels of D-Proline, Sarcosine, Cadmium sulphide (CdS) and Potassium chloride (KCl). The impedance response of the biosensor towards these species was analyzed and is reported in this paper.

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.

A novel gravure printed impedance based flexible electrochemical sensor

A novel flexible electrochemical sensor was successfully gravure printed on a polyethylene terephthalate (PET) film with silver (Ag) electrodes using Ag nanoparticle based ink. The sensor consisted of a circular working electrode with diameter of 1700 µm and a counter electrode with outer and inner diameter of 3900 µm and 2900 µm, respectively. The capability of the fabricated sensor for detecting very low concentrations of toxic chemicals was demonstrated. The electrochemical impedance spectroscopy (EIS) response of the printed sensor revealed a very high sensitivity at pico molar (pM) concentration levels of mercury sulfide (HgS), lead sulfide (PbS), D-proline and sarcosine.

P1.9.12 Fully printed wireless LC sensor for heavy metal detection

This paper reports on the successful development of a fully printed wireless LC sensor for the detection of toxic heavy metals. The sensor, consisting of an inductor, detection coil and interdigitated electrodes (IDE) in planar form, was fabricated using screen and gravure printing technologies on a flexible polyethylene-terephthalate (PET) substrate with silver based ink as metallization. The capability of the printed LC sensor for detecting very low concentrations of toxic heavy metals was demonstrated. The wireless response of the printed LC sensor revealed a very high sensitivity at picomolar levels of cadmium sulphide (CdS) and lead sulphide (PbS).