MICROFLUIDIC SYSTEM FOR OIL SAMPLE ANALYSIS

Abstract

The present invention refers to a system comprising microfluidic devices of extraction, capacitance analysis, together with the smartphone-controlled potentiostat, consisting of a portable system that can be applied on offshore platforms and offering an analytical procedure that requires low levels of samples and chemical ingredients. In addition, the assembly provides the in loco, fast analysis of species having fouling features with high analytical frequency. The ability to carry out these analyzes in low BSW oils represents a strong analytical improvement view of the technical difficulties observed in traditional methods that use liquid-liquid extraction. Thus, the possibility of quickly predicting the ionic composition profile of these water samples becomes a strategy for monitoring, control and decision-making actions in the production chain, making it possible to establish more appropriate fouling inhibition strategies, enabling more proactive actions rather than reactive ones to be taken by the operator. Therefore, unscheduled production stops caused by fouling in the production system are prevented.

Claims

1. A PORTABLE MICROFLUIDIC SYSTEM FOR OIL SAMPLE ANALYSIS, characterized by comprising an electronic language, a potentiostat (which can also be controlled by a smartphone), microfluidic chips (extraction system) and syringe pumps, where probes are inserted into both sides of the microfluidic sensor channels.

2. The SYSTEM, according to claim 1, characterized in that the microfluidic chips for both liquid-liquid extraction and the electronic language are built by methods of polymerization and scaffold removal (PSR) soft lithography and 3D printing technologies.

3. The SYSTEM, according to claim 2, characterized in that the polymers are based on silicone or thermoplastics and epoxy or acrylic resins.

4. The SYSTEM, according to claim 2, characterized in that the sensor obtained by the PSR method, the probes are stainless steel capillaries.

5. The SYSTEM, according to claim 1, characterized in that the probes have a spacing of 200 .Math.m between each other.

6. The SYSTEM, according to claim 4, characterized in that the capillaries are short-circuited with copper pieces, obtaining an association of capacitors in parallel.

7. The SYSTEM, according to claim 4, characterized in that poly(vinyl chloride) hoses connect the capillaries to each other to complete the microfluidic circuit.

8. The SYSTEM, according to claim 1, characterized in that the microfluidic sensors have four or eight pairs of capacitors in parallel.

9. The SYSTEM, according to claim 2, characterized in that the sensor obtained by soft lithography, the flat, gold interdigitated capacitors are deposited on glass plates by physical evaporation techniques in the vapor phase.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be described in more detail below, with reference to the attached figures which, in a schematic and non-limiting manner of the scope of the invention, represent examples of embodiments. In the drawings:

[0019] FIG. 1 illustrates soft lithography and 3D printing technologies, where (1) 2D view and (2) 3D view of the microfluidic chip associated with the extraction step;

[0020] FIG. 2 illustrates (A - 1) a sensor obtained by the PSR method, the stainless steel capillary probes are ready for use; (B - 2) and (C - 3) show the microfluidic sensors obtained with four and eight pairs of capacitors in parallel, respectively; and (D -4) shows a sensor obtained by soft lithography, the flat, interdigitated gold capacitors were deposited on glass plates by physical evaporation techniques in vapor phase, and their area and design were defined by photolithography. These represent the electronic language in different configurations;

[0021] - FIG. 3 illustrates the sequential scheme of operation of the extraction system associated with the electronic language.

DETAILED DESCRIPTION OF THE INVENTION

[0022] The portable system according to the present invention and illustrated in FIG. 3 comprises an electronic language, a potentiostat, microfluidic chips and two syringe pumps. Microfluidic chips of both liquid-liquid extraction and the electronic language system can be built by polymerization and scaffold removal (PSR), soft lithography and 3D printing technologies (FIG. 1 (1) 2D view and (2) 3D view).

[0023] Among the materials used, silicone-based or thermoplastic polymers and epoxy or acrylic resins can be mentioned. In the sensor obtained by the PSR method (FIG. 2 (A)), the ready-to-use probes used were stainless steel capillaries. These probes were inserted on both sides of the microfluidic sensor channels in order to obtain gaps of about 200 .Math.m between each other. These capillaries were short-circuited with copper pieces, obtaining an association of capacitors in parallel. Then, poly(vinyl chloride) hoses connected the capillaries to each other to complete the microfluidic circuit.

[0024] FIG. 2 (B) and (C) show the microfluidic sensors obtained with four and eight pairs of capacitors in parallel, respectively. In the sensor obtained by soft lithography, the flat, gold interdigitated capacitors (FIG. 2 (D)) were deposited on glass plates by physical evaporation techniques in vapor phase, and their area and design were defined by photolithography. Impedance analyzes were performed on portable potentiostats controlled by smartphones, so that analyzes can be performed on offshore platforms. Capacitances of the pairs of electrodes were calculated from the imaginary impedance considering the electrodes as ideally polarizable. Statistical treatment of data by ML was performed using the library algorithms Python.

EXAMPLES

[0025] The following examples are presented to fully illustrate the nature of the present invention and how to practice the same, without, however, being considered limitative of its content.

Example 1: Microfluidic Devices

[0026] The development of easy-to-manufacture microfluidic devices was obtained by using epoxy resins with the aid of a scaffold and also through stereolithography (SLA) 3D printing technology. These microfluidic devices were composed of intertwined channels having sizes of approximately 400 pm, which operated under a turbulent flow regime and presented characteristics of interest such as portability, low cost, capacity for ultra-fast extractions, low consumption of reagents and samples, chemical an d mechanical resistance and long shelf-life.

[0027] This device showed fruitful results concerning the extraction capacity of the aqueous fraction present in crude oil samples with BSW values lower than 1%. The extraction capacity was assessed through the analysis of water conductivity and Ca.sup.2+, Sr.sup.2+ (ICP-OES) and (SCU).sup.2- and Cl.sup.- ions (ion chromatography). The experimental conditions of dilution with toluene, volume of diluent, flow rate, donor and receptor phase ratios were studied in order to maximize the cited extractive process.

Example 2: Electronic Language

[0028] To quantify the ions in the water extracted by the device, an electronic language was developed, which consists of an electrochemical multidimensional sensor based on a single probe and universal capacitive detection in microfluidic devices. Fingerprints of the electronic language were obtained through a single capacitance experiment in low cost, ready-to-use probes (stainless steel capillaries), which form electric double layer capacitors (EDC) and were associated in parallel in the polydimethylsiloxane (PDMS) microfluidic device.

[0029] These devices presented low consumption of samples and were prototyped through a cleanroom-free green, scalable technique. The multidimensional data of differential capacitance of the electrical double layer (Cd) obtained by the sensor were confirmed through macroscopic measurements of capacitance and analysis by microscopy and spectroscopy methods. The sensor was used in the classification and multidetermination of mixtures of three Ba.sup.2+, Ca.sup.2+ and Cl.sup.-. Statistical treatment of the data was carried out using supervised ML techniques, which can be: partial least squares (PLS), random forests (RF), linear discriminant analysis (LDA), Sure Independence Screening and Sparsifying Operator (SISSO), among others. The application of SISSO enabled a simple and linear modeling of the data and selected only 2 Cd data (at different frequencies) that were associated with the ionic charge of the solution in the electric double-layer and the electrode material. Classification accuracy in validation samples was 100.0%. Regressions used for multidetermination showed a high correlation across the range of metal ion concentrations studied (R.sup.2> 0.9996), with an accuracy of 100.0%.

[0030] It should be noted that, although the present invention has been described in relation to the attached drawings, it may be subjected to modifications and adaptations by the skilled person, depending on the specific instance, but as long as it is within the inventive scope defined herein.