Design and applications of a neural networks assisted portable liquid surface tensiometer

In this paper, a portable instrument for surface tension measurements, characterization and applications is described. The instrumentation is operated wirelessly, and samples can be measured in situ. The instrument has changeable different size probes; therefore, it is possible to measure samples from 1 ml up to 10 ml. The response of the measured retraction force and the concentrations of measured surfactant is complex. Therefore, two calibration methods were proposed: (i) the conditional calibration using polynomial and logarithmic fitting and (ii) the neural network trained model prediction of the surfactant concentration in samples. Calibrating the instrument, the neural network trained model showed a superior coefficient of determination (0.999), comparing it to the conditional calibration using polynomial (0.992) and logarithmic (0.991) fit equations

Bekontakčių kapiliarinio formato detektorių kūrimas ir panaudojimas cheminei ir aplinkos analizei

The obvious trends in the development of current analytical instruments for environmental, chemical and bioanalysis are miniaturization and integration. Miniaturized techniques improve performance, throughput and reliability. Many of real samples, particularly in environmental or bio-analysis are very complex and for qualitative and quantitative assessment have to be separated prior to measurement. Capillary electrophoresis and related microseparation techniques are frequently used in environmental, biological and many other fields of analysis. It can be miniaturized and automated. Coupling microseparation technique to miniaturized detection technique leads to the design of perspective instrumentation, which can be applied for environmental analysis. One of the perspective and universal detection techniques capable of detecting various compounds in environmental analysis is contactless conductivity (impedance) detection. The aim of this work was to design a miniature, potentially field portable, compatible with capillary format microseparations, suitable for environmental and other types of analyses detector, which is based on the measurement of complex impedance. The developed system is portable, miniature size, uses wireless data transmission and provides high performance detection characteristics. The detector can be used on the field or on stand-alone rover. Distant experiments can be performed without leaving a laboratory. In addition, experiments can be performed in different environmental sites including environmentally savage sites. Obtained evaluation and application data can be used as a guideline designing similar and more advanced miniaturized detection systems.Miniatiūrizacija ir integravimas yra pagrindinės tendencijos naujausių aplinkotyros, cheminės ir bioanalizės instrumentų kūrime. Tokios technologijos pasižymi geresnėmis charakteristikomis, našumu ir patikimumu. Dauguma realių bandinių, ypač aplinkoje, arba gautų iš biologinės kilmės objektų yra sudėtingi cheminių medžiagų mišiniai ir prieš kokybinę bei kiekybinę analizes, cheminiai junginiai turi būti atskirti vienas nuo kito. Kapiliarinė elektroforezė ir kiti mikro-skirstymo metodai yra dažnai naudojami aplinkos, biologinių ir kitų bandinių analizei. Kapiliarinės elektroforezės metodus įmanoma miniatiūrizuoti ir automatizuoti. Sujungus mikro-skirstymo technologiją su miniatiūrizuota detekcijos sistema įmanoma gauti perspektyvų aplinkos analizės prietaisą. Viena iš daug žadančių detekcijos technologijų, sugebančių aptikti įvairius junginius aplinkoje, yra bekontaktė laidumo (impedanso) detekcija. Šio darbo tikslas buvo sukurti miniatiūrinį, nešiojamą detektorių, kuris pagrįstas kompleksinio impedanso matavimu, tinkantį kapiliarinio formato skirstymo metodams aplinkos ir kitų objektų analizei. Sukurti prietaisai yra nešiojami, mažų dimensijų, turi bevielio duomenų perdavimas galimybę ir pasižymo aukšto lygio detekcijos parametrais. Sistemą galima pritaikyti analizei lauko sąlygomis, arba ant savaeigės robotizuotos sistemos. Ši technologija leidžia atlikti aplinkos tyrimus per atstumą, neišėjus iš laboratorijos. Be to, eksperimentai gali būti atlikti skirtingo tipo aplinkos vietose, įskaitant ir sunkiai pasiekiamas vietas. Taip pat, sukurti detektoriai ir surinkti duomenys gali būti naudojami kaip gairės, kuriant panašią ar tobulesnę aplinkos analizės įrangą.Vytauto Didžiojo universiteta

Research on the computerization of electrochemical impedance Spectrometer

Šiame darbe pateiktas elektrocheminio impedanso spektro matuoklio kompiuterizavimo tyrimas ir konstruktyvūs teorijos įgyvendinimo metodai. Sukurtas miniatiūrizuotas elektrocheminio impedanso spektro matuoklis, kuris gali būti taikomas kapiliarinės elektroforezės skirstymuose – kiekybinėje ir kokybinėje cheminėje analizėje. Impedanso matuoklis gali veikti vienu dažniu, arba skenuoti spektrą prie kelių sužadinimo dažnių. Identifikuotos sukurtos sistemos ir panašių, literatūroje aprašytų, sistemų pagrindinės problemos: (i) žemas detektoriaus jautrumas, (ii) apsunkintas cheminių medžiagų identifikavimo ir kiekybinio nustatymo procesas dėl temperatūros sukeltų bazinės linijos fluktuacijų ir (iii) smailių poslinkio laiko skalėje. Sukurti kompiuterizuoti metodai leidžia išspręsti esmines identifikuotas problemas: (i) adaptyvus analičių migracijos greičiui slenkančio vidurkio metodas padidina detektoriaus duomenų jautrumą; (ii) bazinės linijos temperatūros sukeltų fluktuacijų kompensavimo metodas ištiesina elektroferogramos bazinę liniją; (iii) elektroferogramos laiko skalės kompensavimo remiantis (a) darbine srove ir (b) elektroosmozės žyme ir atraminėmis smailėmis metodai grąžina smailes į jų tikrąsias laiko pozicijas. Sukurti metodai gali būti realizuoti (i) mikro-valdiklyje, (ii) duomenų surinkimo programinėje įrangoje ir (iii) duomenų apdorojimo programinėje įrangoje. Šiame darbe pademonstruota sukurtų metodų realizacija, pritaikymas, problemos ir kitos detalės.In this work the research on computerization of electrochemical impedance spectra detector is described. The miniaturized impedance spectra detector was designed that can be coupled with capillary electrophoresis and applied for qualitative and quantitative chemical analysis. The detector can be operated using the single frequency and is able to scan spectrum using several different excitation frequencies. Main identified problems of the designed system and the similar systems described in the literature are following: (i) low sensitivity of the detection systems, (ii) problematic identification and quantification of the chemical compounds due to temperature induced baseline fluctuations and (iii) peak migration time shifting. Designed computerized methods are capable of solving key problems: (i) migration velocity-adaptive moving average method increases the sensitivity of the detector, (ii) baseline compensation method smoothens the electropherogram baseline, (iii) time scale compensation method based on (a) operating current and (b) reference peaks returns the peaks of chemical compounds to their true positions in the time axis. Designed methods can be realized in: (i) microcontrollers, (ii) data acquisition software and (iii) data analysis software. Realization, application, issues and other details are demonstrated in this work

Design and applications of contactless capillary format detectors for chemical and environmental analysis

Miniatiūrizacija ir integravimas yra pagrindinės tendencijos naujausių aplinkotyros, cheminės ir bioanalizės instrumentų kūrime. Tokios technologijos pasižymi geresnėmis charakteristikomis, našumu ir patikimumu. Dauguma realių bandinių, ypač aplinkoje, arba gautų iš biologinės kilmės objektų yra sudėtingi cheminių medžiagų mišiniai ir prieš kokybinę bei kiekybinę analizes, cheminiai junginiai turi būti atskirti vienas nuo kito. Kapiliarinė elektroforezė ir kiti mikro-skirstymo metodai yra dažnai naudojami aplinkos, biologinių ir kitų bandinių analizei. Kapiliarinės elektroforezės metodus įmanoma miniatiūrizuoti ir automatizuoti. Sujungus mikro-skirstymo technologiją su miniatiūrizuota detekcijos sistema įmanoma gauti perspektyvų aplinkos analizės prietaisą. Viena iš daug žadančių detekcijos technologijų, sugebančių aptikti įvairius junginius aplinkoje, yra bekontaktė laidumo (impedanso) detekcija. Šio darbo tikslas buvo sukurti miniatiūrinį, nešiojamą detektorių, kuris pagrįstas kompleksinio impedanso matavimu, tinkantį kapiliarinio formato skirstymo metodams aplinkos ir kitų objektų analizei. Sukurti prietaisai yra nešiojami, mažų dimensijų, turi bevielio duomenų perdavimas galimybę ir pasižymo aukšto lygio detekcijos parametrais. Sistemą galima pritaikyti analizei lauko sąlygomis, arba ant savaeigės robotizuotos sistemos. Ši technologija leidžia atlikti aplinkos tyrimus per atstumą, neišėjus iš laboratorijos. Be to, eksperimentai gali būti atlikti skirtingo tipo aplinkos vietose, įskaitant ir sunkiai pasiekiamas vietas. Taip pat, sukurti detektoriai ir surinkti duomenys gali būti naudojami kaip gairės, kuriant panašią ar tobulesnę aplinkos analizės įrangą.The obvious trends in the development of current analytical instruments for environmental, chemical and bioanalysis are miniaturization and integration. Miniaturized techniques improve performance, throughput and reliability. Many of real samples, particularly in environmental or bio-analysis are very complex and for qualitative and quantitative assessment have to be separated prior to measurement. Capillary electrophoresis and related microseparation techniques are frequently used in environmental, biological and many other fields of analysis. It can be miniaturized and automated. Coupling microseparation technique to miniaturized detection technique leads to the design of perspective instrumentation, which can be applied for environmental analysis. One of the perspective and universal detection techniques capable of detecting various compounds in environmental analysis is contactless conductivity (impedance) detection. The aim of this work was to design a miniature, potentially field portable, compatible with capillary format microseparations, suitable for environmental and other types of analyses detector, which is based on the measurement of complex impedance. The developed system is portable, miniature size, uses wireless data transmission and provides high performance detection characteristics. The detector can be used on the field or on stand-alone rover. Distant experiments can be performed without leaving a laboratory. In addition, experiments can be performed in different environmental sites including environmentally savage sites. Obtained evaluation and application data can be used as a guideline designing similar and more advanced miniaturized detection systems.Gamtos mokslų fakultetasVytauto Didžiojo universiteta

Contactless capacitive detector for capillary electrophoresis

Capacitance-to-digital conversion technology is a promising technique for chemical analysis. The monitoring of change of capacitance due to presence or lack of certain compound can be applied for volatile compound detection. In present work detector capable of detecting charged analytes in liquid during process of separation is described. Total system can be operated from the battery and is portable. Electrophoretically Separated metal cations can be detected down to sub-micro-molar concentrations. The work describes hardware and design issues and benefitsBiochemijos katedraVytauto Didžiojo universiteta

Capillary electrophoresis-contactless conductivity detection compensation techniques in changing environment

High performance, precision, accuracy and robustness separations and detection in changing environment are hardly achieved. Usually, fluctuations of temperature, electromagnetic radiation, mechanical vibration and other factors negatively affect the quality of the data. Using common separation techniques not only the migration, or retention time, but also baseline drift and peak areas are shifted distorting the final results. In electromigration techniques, this is even more visible due to the fact that current density is proportional to the temperature. What is more important, conductivity readings also provide spoiled data during the change of the temperature. Conventional way to deal with this problem is buffering and regulation of the temperature and other changing conditions. Usually, these devices are operated in the laboratory due to large dimension design and inoperable field-portability. In this work an algorithm is proposed for effective real-time data treatment and improvement of quality of the r esults. Applied methodology improved the precision of migration time and reduced baseline shifting effectivelyInstrumentinės analizės APCVytauto Didžiojo universiteta

Contactless conductivity detection: development and application in pharmaceutical and related sciences

Contactless conductivity detection is one of the most robust and cost effective technologies that can be coupled to capillary electrophoresis, ion, normal phase and HILIC chromatography in quality control of pharmaceuticals and research. During past decade the detector has been miniaturized to the scale of a coin making it easy to integrate the instrument into portable, or rare maintenance requiring instrumentation. The detector is capable of sensing charged molecules, or analytes that alter conductivity of the electrolyte, or media. The literature reports, that contactless conductivity detection can determine inorganic cations and anions and organic ions such as phenolic acids, phenols, amino acids, amines, proteins, oligopeptides, alkaloids and sugars. In this presentation issues designing and optimizing the instrument, developed and in literature reported applications will be reviewedInstrumentinės analizės APCVytauto Didžiojo universiteta

Separations and detection using small scale complex impedance measuring detector

Biochemijos katedraVytauto Didžiojo universiteta

Portable wireless single chip detector for capillary electrophoresis

Separation techniques make analysis of complex mixtures easier. Available on the market bench-top size separation/ detection systems are used in common practice of the analyst. Contrary, scientific community provides more and more data each year related to miniaturization and automation of mentioned systems. However, finding a certified, validated and user friendly system on the market can be a challenge. In this work miniature detector, which is operated from the rechargeable Li-ion battery and provides wireless data communication, is presented. Capacitance-to-digital sensor (integrated circuit) was used as whole detector. Carefully routed printed circuit board with stainless steel rods (electrodes) soldered onto it was used as a base for device. The performance of singleended and differential signal acquisition configuration was compared. Designed detector weight was less than 90 grams (microcontroller, battery and data communication module included). The detector was integrated into commercial capillary electrophoresis system and detection characteristics were tested. Calculated limit of quantification for potassium ions is less than 0.4 μM. Other and mentioned issues related to the design of this detector will be presentedBiochemijos katedraVytauto Didžiojo universiteta

Constructing, optimising and using miniaturised colorimetric equipment with integrated RGB LED

Spectrophotometers and colorimeters used for chemical analysis are expensive and hardly repaired. The priority of this work was to construct cheap, open-source colorimetric equipment that can detect total content of flavonoids, phenolic compounds and to measure radical scavenging activity. Colorimeters and spectrophotometers used in laboratories are big and it is sometimes a problem to transport them to the place where the samples are so mobility and size was the second priority. Simple, cheap, small but reliable colorimeter was a vision of this work. When all tests and optimisations were completed miniaturised colorimeter was determined perfect for measuring absorption of total content of flavonoids, total content of phenolic compounds and radical scavenging activity. Miniaturised colorimeter consists only four main parts: body which was printed with 3D printer “PrintrBot”, light emitting diode, light detector and Arduino Nano microcontroller. Constructed colorimeter was designed to connect to PC via Micro-USB connection and collect information equal to one point per second. Special program “Universal Acquisition 2.21” was designed for miniaturised colorimeter for collecting, processing and averaging data. Optimised miniaturised colorimeter was able to detect total content of flavonoids, total amount of phenolic compounds and measure radical scavenging activity using three different wavelengths containing light emitting diodeGamtos mokslų fakultetasInstrumentinės analizės APCVytauto Didžiojo universiteta