Mohamed Saadaoui

A Disposable paper breathalyzer with an alcohol sensing organic electrochemical transistor.

Breathalyzers estimate Blood Alcohol Content (BAC) from the concentration of ethanol in the breath. Breathalyzers are easy to use but are limited either by their high price and by environmental concerns, or by a short lifetime and the need for continuous recalibration. Here, we demonstrate a proof-of-concept disposable breathalyzer using an organic electrochemical transistor (OECT) modified with alcohol dehydrogenase (ADH) as the sensor. The OECT is made with the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), and is printed on paper. ADH and its cofactor nicotinamide adenine dinucleotide (NAD+) are immobilized onto the OECT with an electrolyte gel. When the OECT-breathalyzer is exposed to ethanol vapor, the enzymatic reaction of ADH and ethanol transforms NAD+ into NADH, which causes a decrease in the OECT source drain current. In this fashion, the OECT-breathalyzer easily detects ethanol in the breath equivalent to BAC from 0.01% to 0.2%. The use of a printed OECT may contribute to the development of breathalyzers that are disposable, ecofriendly, and integrated with wearable devices for real-time BAC monitoring.

CPW-Fed Inkjet Printed UWB Antenna on ABS-PC for Integration in Molded Interconnect Devices Technology

This letter highlights the potential of inkjet-printing on molded interconnect device technology for the realization of ultrawide band (UWB) antennas. Low-cost thermoplastic acrylonitrile butadiene styrene polycarbonate (ABS-PC) substrate is selected for its promising mechanical and thermal properties. First, electrical characterizations of bare ABS-PC are done using resonance cavity method and then the measurements of S-parameters of two 50 Ω-CPW transmission lines, allow the extraction of both relative permittivity and RF losses. Inkjet printing of silver nano ink is used to fabricate those CPW lines on the top of a 2-mm-thick ABS-PC. The measurements show a relative substrate permittivity equal to 2.8 with conductive and dielectric losses of 19.5 dB/m and 2.4 dB/m at 2 GHz, respectively. Then, an UWB antenna based on a half circular disc monopole and a rectangular patch with two steps is designed and realized by inkjet on ABS-PC. This printed antenna provides a good impedance matching over the entire bandwidth of 3 GHz-13 GHz. Radiation pattern is omnidirectionnal in both E and H planes until 5 GHz and is deformed at higher frequencies due to the higher order modes.

Inkjet-Printed PEDOT:PSS Electrodes on Paper for Electrocardiography

Inkjet-printed PEDOT:PSS electrodes are shown to record cutaneous electrophysiological signals such as electrocardiograms via a simple finger-to-electrode contact. The recordings are of high quality and show no deterioration over a 3 month period, paving the way for the development of the next generation of low-cost, convenient-to-use healthcare monitoring devices.

Study of the Electrical Contact in a Fully Inkjet Printed Membrane Switch

Inkjet printing technology is a direct writing fabrication process which demonstrated its ability to pattern a large variety of materials (metals, dielectrics and ceramics) on different substrates. This paper introduces a membrane switch fully fabricated by inkjet printing of silver nanoparticles on polyimide and polyethylene terephthalate substrates. It focuses on electrical measurements of the contact resistance between two inkjet printed silver layers. Low temperature annealing is necessary to prevent substrate damaging and to enable nanoparticles coalescence resulting in a high conductive layer. Best achieved resistivity of the printed silver layer for 150°C annealing temperature is 6 μΩ.cm, disregarding the granular microstructure and an average thickness of 570 nm. Contact resistance is probed with a four point measurement and has a value lower than 1 Ω for an actuation force of 5N. A geometrical model has been developed for a better understanding of the electrical contact in the membrane switch. The device has been tested under cold and hot switching at 5V and 10 mA. For low power applications, the membrane switch proves to be reliable for 105 mechanical actuation cycles. This work validates inkjet technology potential for electrical contact applications.