Xavier Dollat

A novel fabrication method of flexible and monolithic 3D microfluidic structures using lamination of SU-8 films

The fabrication of three-dimensional (3D) microfluidic networks entirely made of SU-8 with integrated electrodes is reported. The described technology allows the fabrication of uncrosslinked SU-8 dry film on a polyester (PET) sheet and its subsequent lamination to form closed microstructures. Unlike other reported methods, transferred layers are patterned following the bonding step allowing a more accurate and simple alignment between levels than techniques using already patterned layers. Dry release of the complete polymer microstructure was demonstrated. Flexible microfluidic chips were obtained. This technique uses simple tools and no wafer bonder is used but lamination techniques which are more collective processes. Limitations in the method for layers thicker than 50 µm have been observed and are discussed. Hydraulic flow experiments have been performed to study the deformation of the cover layer which could influence adjacent flow in a three-dimensional configuration. Important deformations have been observed for layers 10 µm thick and an average pressure greater than 100 kPa. No deformations have been noted for layers with thicknesses greater than 35 µm and for average pressures up to 200 kPa. No failures occurred within the range of the experimental set-up, i.e. up to 300 kPa.

Rackham: An Interactive Robot-Guide

Rackham is an interactive robot-guide that has been used in several places and exhibitions. This paper presents its design and reports on results that have been obtained after its deployment in a permanent exhibition. The project is conducted so as to incrementally enhance the robot functional and decisional capabilities based on the observation of the interaction between the public and the robot. Besides robustness and efficiency in the robot navigation abilities in a dynamic environment, our focus was to develop and test a methodology to integrate human-robot interaction abilities in a systematic way. We first present the robot and some of its key design issues. Then, we discuss a number of lessons that we have drawn from its use in interaction with the public and how that will serve to refine our design choices and to enhance robot efficiency and acceptability

Powering a Commercial Datalogger by Energy Harvesting from Generated Aeroacoustic Noise

This paper reports the experimental demonstration of a wireless sensor node only powered by an aeroacoustic energy harvesting device, meant to be installed on an aircraft outside skin. New results related to the physical characterization of the energy conversion process are presented. Optimized interface electronics has been designed, which allows demonstrating aeroacoustic power generation by supplying a commercial wireless datalogger in conditions representative of an actual flight.

Dynamic inking of large-scale stamps for multiplexed microcontact printing and fabrication of cell microarrays

Microcontact printing has become a versatile soft lithography technique used to produce molecular micro- and nano-patterns consisting of a large range of different biomolecules. Despite intensive research over the last decade and numerous applications in the fields of biosensors, microarrays and biomedical applications, the large-scale implementation of microcontact printing is still an issue. It is hindered by the stamp-inking step that is critical to ensure a reproducible and uniform transfer of inked molecules over large areas. This is particularly important when addressing application such as cell microarray manufacturing, which are currently used for a wide range of analytical and pharmaceutical applications. In this paper, we present a large-scale and multiplexed microcontact printing process of extracellular matrix proteins for the fabrication of cell microarrays. We have developed a microfluidic inking approach combined with a magnetic clamping technology that can be adapted to most standard substrates used in biology. We have demonstrated a significant improvement of homogeneity of printed protein patterns on surfaces larger than 1 cm2 through the control of both the flow rate and the wetting mechanism of the stamp surface during microfluidic inking. Thanks to the reproducibility and integration capabilities provided by microfluidics, we have achieved the printing of three different adhesion proteins in one-step transfer. Selective cell adhesion and cell shape adaptation on the produced patterns were observed, showing the suitability of this approach for producing on-demand large-scale cell microarrays.

Autonomous power supply for aeronautical health monitoring sensors

New applications of embedded systems are envisioned in the context of aeronautics. However, the increasing burden of on-board cabling requires wireless solutions. Moreover, concerns such as safety or system lifetime often preclude the use of electrochemical energy storage. Ambient energy capture, storage and management are therefore key topics. In this paper we illustrate these concepts by describing an actual implementation in the engine harsh environment of an Airbus A380. A thermogenerator was used to harvest ambient energy and the electronics associated with it allows the local system being energy autonomous. All items were devised and tested in order to meet the criteria of DO-160G aeronautical standard. The set of equipment was mounted on aircraft, and submitted to tens of test flights during roughly a year, in very various flight conditions.

Lateral porous silicon membranes with tunable pore size for on-chip separation

In this work, we present a novel fabrication process for the creation of lateral porous silicon membranes with tunable pore size and porosity and their integration into planar microfluidics. Since the formation of porous silicon by anodization is highly dependent on the dopant type and concentration, we use ion implantation to manipulate the local dopant concentration in order to control the membrane properties. The dead-end filtration capability of our lateral porous silicon membranes integrated within planar microchannels is demonstrated by adequately retaining 300 nm diameter beads, while molecules such as fluorescein and miRNA permeate the membranes.

Coupling Supercapacitors and Aeroacoustic Energy Harvesting for Autonomous Wireless Sensing in Aeronautics Applications

Abstract This paper reports for the first time the experimental demonstration of a wireless sensor node only powered by an aeroacoustic energy-harvesting device, meant to be installed on an aircraft outside skin. Aeroacoustic noise is generated on purpose to serve as a means of converting mechanical energy from high velocity airflow into electrical energy. Results related to the physical characterization of the energy conversion process are presented. The proposed aeroacoustic transducer prototype, consisting in a rectangular cavity fitted with a piezoelectric membrane, is shown to deliver up to 2 mW AC power under Mach 0.5 airflow. Optimized power management electronics has been designed to interface with the transducer, including a self-powered Synchronized Switch Harvesting on Inductor (SSHI) interface circuit and an efficient buck-boost DC/DC converter. The design of micropower auxiliary circuits adds functionality while preserving high efficiency. This circuit stores energy in supercapacitors and is able to deliver a net output DC power close to 1 mW. A fully autonomous system has been implemented and tested, successfully demonstrating aeroacoustic power generation by supplying a battery-free wireless datalogger in conditions representative of an actual flight.