PhD Student at École de technologie supérieure studying Carbon Nanotube MEMS.


Taking the idea of printed electronics to a whole new level

From Printing paper to Printing electronic circuits Consider printing an electronic circuit at home using a multi functional printer or printing a light bulb to replace a broken one. It is getting one step closer to reality using Aerosol Jet Printing What is Aerosol Jet Printing (AJP)? AJP is a Computer Aided Design (CAD) driven vector based printing method that uses a sheath of inert gas to tightly focus a beam of aerosol onto a substrate. The Aerosol Jet process cost effectively prints high resolution electronic circuits and components on 2D and 3D surfaces from a wide range of materials including conductive nano-particle metal inks, dielectric pastes, semiconductor and other functional materials. Potential Applications enabled by AJP The technology behind Aerosol Jet can print electronic and biological components onto 2D and 3D surfaces. By tightly integrating electronic circuitry with physical packaging, Aerosol Jet is fueling growth in new consumer and military applications where increased functionality in smaller spaces is a key driving factor. Leading research institutes have successfully fabricated all elements of a Thin Film Transistor (TFT) using Aerosol Jet printing technology without involving any photolithography patterning or surface pretreatment steps. The unique multi-material deposition capability of Aerosol Jet technology enabled four distinct materials to be printed into four separate layers to print CNT-TFTs


Printed thin film transistors and CMOS inverters based on semiconducting carbon nanotube ink purified by a nonlinear conjugated copolymer

Abstract: Two innovative research studies are reported in this paper. One is the sorting of semiconducting carbon nanotubes and ink formulation by a novel semiconductor copolymer and second is the development of CMOS inverters using not the p-type and n-type transistors but a printed p-type transistor and a printed ambipolar transistor. A new semiconducting copolymer (named P-DPPb5T) was designed and synthesized with a special nonlinear structure and more condensed conjugation surfaces, which can separate large diameter semiconducting single-walled carbon nanotubes (sc-SWCNTs) from arc discharge SWCNTs according to their chiralities with high selectivity. With the sorted sc-SWCNTs ink, thin film transistors (TFTs) have been fabricated by aerosol jet printing. The TFTs displayed good uniformity, low operating voltage (±2 V) and subthreshold swing (SS) (122–161 mV dec−1), high effective mobility (up to 17.6–37.7 cm2 V−1 s−1) and high on/off ratio (104–107). With the printed TFTs, a CMOS inverter was constructed, which is based on the p-type TFT and ambipolar TFT instead of the conventional p-type and n-type TFTs. Compared with other recently reported inverters fabricated by printing, the printed CMOS inverters demonstrated a better noise margin (74% 1/2 Vdd) and was hysteresis free. The inverter has a voltage gain of up to 16 at an applied voltage of only 1 V and low static power consumption.

Pub.: 26 Jan '16, Pinned: 30 Apr '17

3-D Printed Adjustable Microelectrode Arrays for Electrochemical Sensing and Biosensing.

Abstract: Printed Electronics has emerged as an important fabrication technique that overcomes several shortcomings of conventional lithography and provides custom rapid prototyping for various sensor applications. In this work, silver microelectrode arrays (MEA) with three different electrode spacing were fabricated using 3-D printing by the aerosol jet technology. The microelectrodes were printed at a length scale of about 15 μm, with the space between the electrodes accurately controlled to about 2 times (30 μm, MEA30), 6.6 times (100 μm, MEA100) and 12 times (180 μm, MEA180) the trace width, respectively. Hydrogen peroxide and glucose were chosen as model analytes to demonstrate the performance of the MEA for sensor applications. The electrodes are shown to reduce hydrogen peroxide with a reduction current proportional to the concentration of hydrogen peroxide for certain concentration ranges. Further, the sensitivity of the current for the three electrode configurations was shown to decrease with an increase in the microelectrode spacing (sensitivity of MEA30: MEA100: MEA180 was in the ratio of 3.7: 2.8: 1), demonstrating optimal MEA geometry for such applications. The noise of the different electrode configurations is also characterized and shows a dramatic reduction from MEA30 to MEA100 and MEA180 electrodes. Further, it is shown that the response current is proportional to MEA100 and MEA180 electrode areas, but not for the area of MEA30 electrode (the current density of MEA30 : MEA100 : MEA180 is 0.25 : 1 : 1), indicating that the MEA30 electrodes suffer from diffusion overlap from neighboring electrodes. The work thus establishes the lower limit of microelectrode spacing for our geometry. The lowest detection limit of the MEAs was calculated (with S/N = 3) to be 0.45 μM. Glucose oxidase was immobilized on MEA100 microelectrodes to demonstrate a glucose biosensor application. The sensitivity of glucose biosensor was 1.73 μAmM(-1) and the calculated value of detection limit (S/N = 3) was 1.7 μM. The electrochemical response characteristics of the MEAs were in agreement with the predictions of existing models. The current work opens up the possibility of additive manufacturing as a fabrication technique for low cost custom-shaped MEA structures that can be used as electrochemical platforms for a wide range of sensor applications.

Pub.: 29 Mar '16, Pinned: 30 Apr '17

Highly flexible and transparent solid-state supercapacitors based on RuO2/PEDOT:PSS conductive ultrathin films

Abstract: Transparent, conductive electrodes are important in many applications such as touch screens, displays and solar cells. Transparent energy storage systems will require materials that can simultaneously act as current collectors and active storage media. This is challenging as it means improving the energy storage capability of conducting materials while retaining transparency. Here, we have used aerosol-jet spraying strategy to prepare transparent supercapacitor electrodes from ruthenium oxide/poly(3,4-ethylenedioxythiophene): poly(styrene-4-sulfonate), (RuO2/PEDOT: PSS) hybrid thin films. These films combine excellent transparency with reasonably high conductivity (DC conductivity =279 S/cm) and excellent volumetric capacitance (CV =190 F/cm3). We demonstrate electrodes with historical high transparency of 93% which display an areal capacitance of C/AC/A=1.2 mF/cm2, significantly higher than the rest reported electrodes with comparable transparency. We have assembled flexible, transparent, solid-state symmetric devices which exhibit T  =80% and C/AC/A=0.84 mF/cm2 and are stable over 10,000 charge/discharge cycles. Asymmetric solid-state device with RuO2/PEDOT: PSS and PEDOT: PSS thin films as positive and negative electrodes, respectively, display an areal capacitances of 1.06 mF/cm2, a maximum power density (P/A)(P/A) of 147 μW/cm2 and an energy density (E/A)(E/A) of 0.053 μWh/cm2. Furthermore, large area transparent solid-state supercapacitor device has been built. We believe the solution-processed transparent films could be easily scaled-up to meet the industrial demands.

Pub.: 27 Aug '16, Pinned: 30 Apr '17