Gregory Tortissier

Insole Pedometer With Piezoelectric Energy Harvester and 2 V Organic Circuits

A shoe insole pedometer, which consists of a piezoelectric energy harvester and a 2 V organic pedometer circuit, has been developed as a first step toward the application of flexible large-area energy harvesting. A pseudo-CMOS 14 bit step counter records the number of steps up to 16383 steps using the harvested power. To increase the noise margin of the pseudo-CMOS logic circuits, a negative voltage is generated by an organic charge pump circuit and is applied to the pseudo-CMOS inverters and transmission gates in the flip-flops in the step counter. A pseudo-CMOS Schmitt trigger inverter used to feed clean square pulses to the step counter is presented. This paper describes the details of the insole pedometer and provides measurement results and some discussion.

Insole pedometer with piezoelectric energy harvester and 2V organic digital and analog circuits

Energy harvesting is an enabling technology for realizing an ambient power supply for wireless sensor nodes and mobile devices. By using flexible photovoltaic cells and piezoelectric films, we can readily harvest ambient energy if flexible energy harvesters can be realized. Conventional silicon circuits, however, are not best suited to realizing flexible large-area energy harvesters because they are not mechanically conformable to uneven surfaces such as shoes. To address this challenge, we propose an organic insole pedometer with a piezoelectric energy harvester in this paper as the first step toward ambient energy harvesting using organic flexible electronics.

Love Wave Characterization of the Shear Modulus Variations of Mesoporous Sensitive Films During Vapor Sorption

Anomalous responses of acoustic humidity sensors coated with mesoporous titania sensitive films have been observed at high humidity levels, due to capillary contraction that alters the film mechanical behavior. As the methods commonly used to assess the elasticity of thin films are difficult to apply during sorption, a dedicated method for the characterization of the variations of the elastic shear modulus of thin films under humidity exposure has been developed. The method combines a Love wave platform with environmental ellipsometric porosimetry (EEP). In the presented approach, EEP measures the thickness of the film and the adsorbed humidity volume fraction under vapor exposure, while the Love wave platform provides the phase velocity shifts induced by water sorption. These parameters then feed an accurate model of Love wave propagation in the multilayered platform for the derivation of the shear modulus of the sensitive film. The method was applied to 100 ± 10 nm thick mesoporous titania films, with 25 ± 1% porosity, under relative humidity exposure in the 3%-95% range. It successfully determined decreases of 39% and 67% of the shear modulus during adsorption and desorption, respectively, from a 3.1 GPa initial value.

Mesoporous thin films as versatile sensitive matrices on Love wave sensors for fast sub-ppm vapor detection

Love wave gas sensors with mesoporous thin film as sensitive layers are presented. They are dedicated to volatile organic compound vapor detection. Mesoporous films of SiO2 were prepared using the Sol-Gel process and deposited on the devices acoustic path. The obtained films have been characterized by ellipsometry resulting in the determination of porosity and pore size distribution in the film and of water adsorption isotherms. Ethanol (130–2000ppm) and toluene (70–1000ppm) exposures resulted in frequency shifts up to 20 kHz, showing the high sensitivity of the mesoporous-based Love wave devices.

Guided SH-SAW characterization of elasticity variations of mesoporous TiO 2 sensitive films during humidity sorption

Anomalous responses of acoustic humidity sensors coated with mesoporous titania have been observed at high humidity levels, due to capillary contraction that alters the film mechanical behavior. As the methods commonly used to assess the elasticity of thin films are difficult to apply during sorption, a dedicated method for the characterization of the variations of the elastic shear modulus of thin films under humidity exposure has been developed. The method combines a guided shear-horizontal surface acoustic wave (guided SH-SAW or Love wave) platform with environmental ellipsometric porosimetry (EEP). In the presented approach, EEP measures the thickness of the film and its adsorbed humidity volume fraction under vapor exposure, while the guided SH-SAW platform provides the phase velocity shifts induced by water sorption. These parameters then feed an accurate model of Love wave propagation in the multilayered platform for the derivation of the shear modulus of the sensitive film. The method was applied to 100 ± 10 nm thick mesoporous titania films, with 25 ± 1% porosity, under relative humidity exposure in the 3%-95% range. It successfully determined decreases of 39% and 67% of the shear modulus during adsorption and desorption, respectively, from a 3.1 GPa initial value.

Guided SH-SAW toluene sensors with mesoporous silica sensitive coatings: Increased sensitivity through mesostructuration control

Thanks to high specific surface areas, mesoporous silica films have been considered as sensitive coatings for guided shear-horizontal surface acoustic wave toluene sensors. In order to increase their sensitivity, the influence on toluene detection of the structuring agent used in the evaporation-induced-self-assembly fabrication process of these inorganic films has been studied. In this paper, F127 block copolymer is compared to cethyltrimethylammonium bromide (CTAB). Sensors coated with 100 nm thick films structured with CTAB show an average sensitivity of 14 Hz.ppm−1 for toluene concentrations in the 130–1040 ppm range at room temperature, which is 4.5 times higher than the sensitivity obtained with films of similar thicknesses and porosities that were structured with F127.

Enhanced CF 4 plasma treated polymer film for flexible display application

A MEMS flexible display device, based on transparent and flexible PEN substrate, is fabricated by inkjet printing associated with CF4 plasma surface treatment.

Flexible display system based on MEMS Fabry-Perot interferometer

Previous works on MEMS actuated Fabry-Perot interferometer (FPI) highlighted promising results for flexible display applications. Three primary color pixels have indeed been obtained using both photolithography [1] and Roll-to-Roll printing process [2] with satisfying color purity and transmittance. However both of these processes are expensive and time-consuming for preparing master micropatterns. For these reasons, a new process based on inkjet printing has been set up. It contributes in a more ecological-friendly, high reproducible and fast process development while targeting improved features.