This paper reports on the development of an autonomous instrument based on an array of eight resonant microcantilevers for vapor detection. The fabricated sensors are label-free devices, allowing chemical and biological functionalization. In this work, sensors based on an array of silicon and synthetic diamond microcantilevers are sensitized with polymeric films for the detection of analytes. The main advantage of the proposed system is that sensors can be easily changed for another application or for cleaning since the developed gas cell presents removable electrical connections. We report the successful application of our electronic nose approach to detect 12 volatile organic compounds. Moreover, the response pattern of the cantilever arrays is interpreted via principal component analysis (PCA) techniques in order to identify samples.

The problems due to lost circulation events may represent a major source of expenses for drilling operators, even if their consequences do not have all the same level of gravity. Probably the most problematic situations are the naturally fr

Summary: Drill-in fluids are generally water-based muds (WBMs) containing a viscosifier, a fluid-loss reducer, salts, and sized calcium carbonate particles. Formation damage mechanisms induced by the use of WBM formulations have been extensively studied and correspond to different phenomena such as water trapping, polymer adsorption and retention, and particle plugging. In this paper, a detailed study was carried out on the behavior of scleroglucan-based formulations generally proposed for high-temperature zones and/or high-permeability reservoirs and on the comparison with performances of xanthan-containing formulations. This work covers not only the effect of the fluid composition, including the presence or absence of drilled solids, but also the filtration conditions, such as shear rate and temperature. Mud filtrates have been characterized in terms of polymer content and by multiangle laser light scattering coupled with size-exclusion chromatography (SEC/MALLS) and filter cakes by cryo-SEM.Filtration curves obtained under static conditions can be related to the rheological behavior and thermal stability of the biopolymer used as a viscosifier but not related to the solid content of the mud. Under dynamic conditions, the filtration curve strongly depends on the aggregation tendency of the scleroglucan sample.Scleroglucan-based drill-in fluids present very good properties compared to classical water-based formulations at 120°C using a commercially available scleroglucan sample. The cryo-SEM dynamic filter-cake observations confirm a lower filter-cake permeability obtained under dynamic conditions with an homogeneous structure, no aggregates, and a structural polymer network.When in contact with a borehole, for the same circulation time, a scleroglucan formulation will invade half the zone invaded by a xanthan-based formulation.

In this paper, we present how complementary characterization techniques, such as electrical measurements with a vector network analyzer (VNA), optical measurements with a laser Doppler vibrometer (LDV), and numerical simulations with the finite element method, coupled with spectral domain analysis (FEMSDA), allow us to independently access different properties of a SAW device and fully characterize its operation using the coupling-of-modes theory (COM). A set of chemical SAW sensors coated with parylene C layers of different thicknesses (1, 1.5, and 2 µm) and an uncoated sensor were used as test samples. The sensors represent dual-channel electroacoustic delay lines operating in the vicinity of 77 MHz. The IDTs consist of split aluminum electrodes deposited on a AT-cut quartz substrate. The thickness-dependent influence of the parylene C layer was observed on the operating frequency (SAW velocity), static capacitance, attenuation, crosstalk, and reflection coefficient. COM parameters were reported for the four cases considered; measured and simulated data show good agreement. The presented approach is suitable for the design, characterization, and validation of polymer film-coated SAW sensors.

Recently, the need for a real time and less invasive solution to replace in-lab blood analysis by analyzing in-situ biological fluids (sweat, saliva, tear, urine, interstitial fluid) has grown alongside the development of micro fabrication techniques. pH determination is crucial for health monitoring (e.g., fetal acidosis supervision, sport activity, tumor detection and wound monitoring). Our work focuses on developing a potentiometric microsensor, targeting pH measurement on the fetal scalp during labor, employing nanoporous titanium nitride (TiN) as alternative sensing material. The pH probe contains a working electrode of 400 μm x 800 μm in size, integrated on a flexible polyimide substrate, creating an ultra-thin sensor with thickness below 20 μm. Microfabrication process and a complete characterization on performance of our flexible pH microsensor are presented, demonstrating a sensitivity of 53.2 mV/pH. Hysteresis was found at 3 mV maximum after 6 cycles, demonstrated a good reproducibility and led to a precision of 0.05 in pH. A comparison of the performance between porous and flat TiN (sensitivity of 53.7 mV/pH, hysteresis maximum of 5 mV and precision of 0.09 in pH) is presented, along with an evaluation of the dependence in the electrode size versus their performances. A preliminary in-vivo test was conducted on mice with the probe implanted under the skin. We recorded a stable open circuit voltage signal under anesthesia conditions. A compact measurement system was designed with a customized LCD screen for signal visualization, an EZO™ ORP circuit for data acquisition and an integrated SD card for data storage.