Considering the difficulty of measuring neurotransmitters in the field of biomedical research, a portable autonomous sensing and analysis system of neurotransmitters is needed. This type of device would improve the diagnostics of neurodegenerative diseases such as Alzeimer, Parkinson, Huntington diseases. Thus, in this work, we present a synthesis research paper to describe our device capable of measuring neurotransmitters in a liquid sample using functionalized ultrastable gold nanoparticles. It uses a colorimetric sensor to measure neurotransmitter indirectly. Indeed, using the colorimetric sensing approach, the plasmonic resonance band of nanoparticles shifts when they interact with neurotransmitters. The functionalization of the nanoparticles with dopamine-specific aptamer increases the response and selectivity towards the neurotransmitter of interest. Also, using ultrastable gold nanoparticles5 provides the potential to expose them to harsh conditions without agglomeration. Those harsh conditions includes the presence of salts that would otherwise compromise the efficiency of the sensing as well as conditions that are used to wash and clean the solutions (freeze drying, heating, ultracentrifugation and autoclaving). By being able to resist to those types of conditions, it gives the potential to recycle the nanoparticles to be reused for several sensing cycles. This sensing system uses a grism-based spectrometer design for the colorimetric analysis of neurotransmitters covering a bandwidth of 420 to 620 nm. Moreover, the system includes a microfluidic module for the manipulation of samples as well as an electronic module for data acquisition and analysis. Altogether, the system showed that the absorption spectrum of a nanoparticles sample with a resolution of 0.7 nm can be extracted autonomously using this system.
The sensing of neurotransmitters is currently a difficult task for scientists in the field of biomedical research. The design of a new compact and accurate sensor would benefit greatly the research being done on neurotransmitters. In this effect, optoelectronic sensors are ideal candidate as they are non-invasive and non-reactive to the test sample. This work describes the design, fabrication, calibration, and tests of a new type of neurotransmitter sensor using spectral analysis based on a Grism. This new optical sensor was fitted with a self calibrating algorithm and showed superior resolution as well as a smaller footprint than previously observed.
In this work, we present numerical simulation results of a designed microfluidic probe for liquid extraction and local drug delivery. The designed probe ensures three different operating modes which are, direct sampling, direct drug delivery and diffusion based sampling. The reported results of finite elements simulation shows that using diffusion phenomena a molecular sample can be extracted from an aqueous sample with this probe. In addition, the best operational parameters of the probe were a tilt angle of 25° and an inlet/outlet velocity of 2 μm/s in order to get the higher concentration of extracted molecule in the buffer solution.
Wire-free power supplies provide portability, flexibility and cost efficiency as they reduces hardware complexity. Thus, in this paper we designed a portable pH sensor based on a microbial fuel cell (MFC) as a wire free energy source. Our MFCs supplied 0.127 mW to power our ultra-low power portable pH sensor. The error of the newly designed pH sensor is less than 5% when pH is between 4 and 10. Also it provides, an autonomy of 4 hours when the pH sensor is continuously used.
This paper describes a proof of concept of a microfluidic dipole to sample cerebral fluid. It consists of a portable microfluidic probe which injects a buffer in one inlet and draws it from the other one after passing through a contact zone with the external liquid. Finite elements method modelling (FEM) shows a very stable liquid flow across the complete probing area. Furthermore, we determined that a design generating turbulence is likely to be more useful to capture brain molecules. Molecules displacement due to diffusion phenomena takes about 25 ms to diffuse over a 1 mm probe gap. Finally, our experiment showed that, to obtain a stable flow without turbulence the maximum inlet and outlet pressure is 0.05 mPa for the two tested configuration of dipole.
In this work, we present a new microspectrometry FTIR-based biosensor for the analysis of sugar based solutions using various solvent and various types of sample handling support (SHS). We used methanol as solvent because it does not interact with infrared (IR) beam. In addition, it ensures a rapid evaporation in order to form a thin layer of targeted molecules on the conventional SHS. The later consists of a total reflective mirror (TRM). Because of methanol toxicity, we developed a new setup for aqueous samples analysis based on accelerated solvent evaporation. The achieved limit of detection (LOD) using the developed biosensor was 3 mM for both, Glucose and Fructose molecules.
In this project we present a microfluidic platform with in-channel micro-electrodes for in situ screening of bio/chemical samples through a lab-on-chip system. We used a novel method to incorporate electrochemical sensors array (16x20) connected to a PCB, which opens the way for imaging applications. A 200 μm height microfluidic channel was bonded to electrochemical sensors. The micro-channel contains 3 inlets used to introduce phosphate buffer saline (PBS), ferrocynide and neurotransmitters. The flow rate was controlled through automated micro-pumps. A multiplexer was used to scan electrodes and perform individual cyclic voltammograms by a custom potentiostat. The behavior of the system was linear in terms of variation of current versus concentration. It was used to detect the neurotransmitters serotonin, dopamine and glutamate.
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