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Ethyl valerate (green apple flavour) and hexyl acetate (pear flavour) are short-chain esters with fruity notes that are widely used in food, cosmetic and pharmaceutical industries. Crude Staphylococcus simulans lipase was immobilized on different supports. The CaCO3 was selected as the most suitable support offering maximum adsorption capacity. Different reaction parameters for enhancing ester formation were investigated. In fact, higher conversion of ethyl valerate (51%) was achieved by the addition of 20% (w/w) of water to the reaction mixture, using 200 IU of immobilized lipase, a molar ratio valeric acid to ethanol of 1 and at 37 °C. No decrease of the synthesis activity was observed for 10 cycles of use of the immobilized lipase. In the case of the hexyl acetate, the optimum conditions, giving 41% of conversion, are obtained with 10% (w/w) of initially added water, 100 IU of immobilized lipase, a molar ratio acetic acid to hexanol of 1 and at 37 °C. Immobilized lipase could be repeatedly used for five cycles without a decrease of synthesis activity.

International audience; In this paper, different strategies for post-silicon yield improvement of MEMS convective accelerometers are explored. A key feature of the proposed strategies is that they can be implemented at low-cost using electrical test equipment since they only rely on the measurement of the relative deviation of Wheatstone bridge impedance due to power dissipation in the heating element. Different electrical test flows are defined that implement either sensitivity binning, sensitivity calibration, or both. Optionally, an additional constraint can be inserted in the test flows in case power consumption performance has also to be satisfied in addition to sensitivity. The efficiency of the different strategies is evaluated and discussed considering a population of 1,000 devices generated through Monte-Carlo simulation. Finally, experimental measurements that validate the calibration principle are presented.

International audience; In this paper, we propose an alternate electrical-only strategy to perform both test and calibration of MEMS convective accelerometers' sensitivity. The idea is calibrate device sensitivity through the adjustment of the power dissipated in the heater element. For this, the system is equipped with an on-chip programmable digital pulse modulated generator and an iterative search procedure based on simple impedance measurements is implemented. The method is evaluated through Monte-Carlo simulations considering typical process variations and results are presented to demonstrate the potentialities of the technique.

International audience; This paper presents a behavioral model that can be used to improve the manufacturability of systems based on MEMS convective sensors. This model permits to handle faults related to process scattering, taking into account not only the electrical and lateral geometrical parameters but also the influence of the cavity depth. Moreover correlations between conductive and convective phenomena are included. The model is validated with respect to FEM simulations and a very good agreement is obtained between the behavioral model and FEM results. The proposed model can then be used in system-level simulations, for instance to evaluate the impact of process scattering on the performances of the sensing part and/or to investigate different design and calibration strategies with respect to the system robustness.