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Since many years, a new generation of materials called « smart materials » and defined by their capacity to adapt to their environment is intensively developed. Systems sensitive to different stimuli such as pH, light or ionic strength have been reported. One of these stimuli can also be a mechanical force which is involved in many reactions in nature such as, cells adhesion and proliferation, tissues growing or even plants developments. The aim of my thesis was dedicated to the elaboration of mechano-responsive materials. More precisely, materials that transform a stretching constraint into a chemical signal by mimicking the physical processes used by nature, namely protein conformational changes. We planned to achieve this goal by covalently grafting proteins or enzymes onto a stretchable substrate or incorporating them into cross-linked polymer networks. Stretching these materials should induce protein conformational changes leading to modifications of their properties.; Depuis plusieurs années, une nouvelle génération de matériaux appelés “matériaux intelligents” et définis par leur capacité d’adaptation à leur environnement, est intensément développée. Des systèmes sensibles à différents stimuli tels que le pH, la lumière, ou encore une force mécanique, impliquée dans un grand nombre de processus naturels, comme l’adhésion et la prolifération cellulaire, ont été rapportés. Ce travail de thèse a ainsi été dédié au développement de matériaux mécano-sensibles. Plus précisément de matériaux transformant une contrainte mécanique en un signal chimique, en mimant le processus physique utilisé par la nature, à savoir des changements conformationnels de protéines. Nous avons donc cherché à atteindre ce but en greffant covalemment des protéines ou des enzymes sur un substrat élastomère. Etirer le substrat devant induire des modifications de structure des protéines, conduisant ainsi à des modulations de leurs propriétés.

This paper presents a method to integrate biocompatible passive microfluidic systems within a sensing platform to allow continuous analysis of sweat in a wearable microsystem. The technology is promising for miniaturization of systems to enable access to biochemical information at the surface of human skin. The microfluidics are originally designed to work with ultra-low volumes of liquid to enable sweat analysis at any physiological situation (during intense physical activity or when at rest). Flow rates vary from 10s to 100s of pico-liters per second which can be adjusted by design. Capillary forces are used to move the liquid inside the microchannels in order to avoid power consumption. The SU8-based process is compatible with standard semiconductor techniques making it scalable, and suitable for integration with different sensing technologies. In this work, the microfluidic devices have been designed and integrated on top of ISFET devices.

Presented herein are devices for collecting and/or channeling a biofluid (e.g., sweat, tears, saliva) and detecting and/or quantifying one or more biomarkers in the biofluid. The biomarker(s) may include, for example, ions, salts thereof, hormones and/or steroids, proteins, metabolites and organic compounds. In certain embodiments, the devices described herein include a specially designed interface and a zero-energy micro pump that allow the device to be comfortably affixed directly to the skin of a user while biofluid is efficiently and non-invasively collected from the skin of the user. In certain embodiments, the device is housed on or in another wearable device, such as a wrist band or a smart watch. In certain embodiments, the devices described herein are disposable (e.g., after a certain period of use and/or wear the device can be disposed and replaced with a low- cost replacement).