Microfluidic Paper-based Analytical Devices Research Articles

Paper-Based Analytical Devices for Colorimetric and Luminescent Detection of Mercury in Waters: An Overview.

Lab-on-paper technologies, also known as paper-based analytical devices (PADs), have received increasing attention in the last years, and nowadays, their use has spread to virtually every application area, i.e., medical diagnostic, food safety, environmental monitoring, etc. Advantages inherent to on-field detection, which include avoiding sampling, sample preparation and conventional instrumentation in central labs, are undoubtedly driving many developments in this area. Heavy metals represent an important group of environmental pollutants that require strict controls due to the threat they pose to ecosystems and human health. In this overview, the development of PADs for Hg monitoring, which is considered the most toxic metal in the environment, is addressed. The main emphasis is placed on recognition elements (i.e., organic chromophores/fluorophores, plasmonic nanoparticles, inorganic quantum dots, carbon quantum dots, metal nanoclusters, etc.) employed to provide suitable selectivity and sensitivity. The performance of both microfluidic paper-based analytical devices and paper-based sensors using signal readout by colorimetry and luminescence will be discussed.

Pumpless three-dimensional photo paper-based microfluidic analytical device for automatic detection of thioredoxin-1 using enzyme-linked immunosorbent assay.

Microfluidic-based biosensors have been developed for their precise automatic reaction control. However, these biosensors require external devices that are difficult to transport and use. To overcome this disadvantage, our group made an easy-to-use, cheap, and light pumpless three-dimensional photo paper-based microfluidic analytical device (3D-μPAD; weight: 1.5g). Unlike conventional paper-based microfluidic analytical devices, the 3D-μPAD can be used to control fluid flow in a 3D manner, thus allowing sophisticated multi-step reaction control. This device can control fluid flow speed and direction accurately using only the capillary-driven flow without an external device like a pump. The flow speed is controlled by the width of the microfluidic channel and its surface property. In addition, fluid speed control and 3D-bridge structure enable the control of fluid flow direction. Using these methods, multi-step enzyme-linked immunosorbent assay (ELISA) can be done automatically in sequence by injecting solutions (sample, washing, and enzyme's substrate) at the same time in the 3D-μPAD. All the steps can be performed in 14min, and data can be analyzed immediately. To test this device, thioredoxin-1 (Trx-1), a biomarker of breast cancer, is used as the target. In the 3D-μPAD, it can detect 0-200ng/mL of Trx-1, and the prepared 3D-μPAD Trx-1 sensor displays excellent selectivity. Moreover, by analyzing the concentration of Trx-1 in real patients and healthy individuals' blood serum samples using the 3D-μPAD, and comparing results to ELISA, it can be confirmed that the 3D-μPAD is a good tool for cancer diagnosis.

The pursuit of further miniaturization of screen printed micro paper-based analytical devices utilizing controlled penetration towards optimized channel patterning

One of the main objectives of microfluidic paper-based analytical devices is to present solutions particularly, for applications in low-resource settings. Therefore, screen-printing appears to be an attractive fabrication technique in the field, due to its overall simplicity, affordability, and high-scalability potential. Conversely, the minimum feature size attained using screen-printing is still rather low, especially compared to other fabrication methods, mainly attributed to the over-penetration of hydrophobic agents, underneath defined patterns on masks, into the fiber matrix of paper substrates. In this work, we propose the use of the over-penetration to our advantage, whereby an appropriate combination of hydrophobic agent temperature and substrate thickness, allows for the proper control of channel patterning, rendering considerably higher resolutions than prior arts. The implementation of Xuan paper and nail oil as novel substrate and hydrophobic agent, respectively, is proposed in this work. Under optimum conditions of temperature and substrate thickness, the resolution of the screen-printing method was pushed up to 97.83 ± 16.34 μm of channel width with acceptable repeatability. It was also found that a trade-off exists between achieving considerably high channel resolutions and maintaining high levels of repeatability of the process. Lastly, miniaturized microfluidic channels were successfully patterned on pH strips for colorimetric pH measurement, demonstrating its advantage on negligible sample-volume consumption in nano-liter range during chemical measurement and minimal interference on manipulation of precious samples, which for the first time, is realized on screen-printed microfluidic paper-based analytical devices.

Simple gunshot residue analyses for estimating firing distance: Investigation with four types of fabrics

This work presents two simple methods for estimating the firing distance from the gunshot residues (GSRs) on fabric targets. Four types of fabric targets, namely twill weave denim cotton-polyester (80/20), jersey knitting 100% cotton, plain weave cotton-polyester (80/20) and plain weave cotton-polyester (60/40), were employed. The firing tests were carried out using these white fabrics as targets at distances of 5–100 cm, respectively. In the first method, digital images of the black GSRs on fabric materials were recorded inside an illuminated box and the inverted gray intensity values were plotted against the firing distances. Since the plots of all fabrics are not significantly different, the estimation of firing distance employs the same exponential curve for all test fabrics. Although simple, the imaging method is not suitable for dark-colored materials. A chemical-based method was therefore developed as an alternative method. In the second method, a small disposable microfluidic paper-based analytical device (μPAD) was employed for detecting Pb(II) extracted from the GSRs. The μPAD method uses the measurement of the length of a narrow band of a pink color resulting from reaction between rhodizonate reagent and the Pb(II) extract. The plots indicated that the data of thick denim material are significantly different to other test fabrics which are much thinner. These three fabrics share the same estimation curve. However, it is recommended that the separate estimation curve for denim materials must be used. Both methods are suitable for short range firing distance, no further than 60 cm, since at greater distances the inverted gray intensity and the ‘band-length’ methods are unable to detect the GSRs.

Design and Functionalization of a µPAD for the Enzymatic Determination of Nitrate in Urine.

In this work, the design of a microfluidic paper-based analytical device (μPAD) for the quantification of nitrate in urine samples was described. Nitrate monitoring is highly relevant due to its association to some diseases and health conditions. The nitrate determination was achieved by combining the selectivity of the nitrate reductase enzymatic reaction with the colorimetric detection of nitrite by the well-known Griess reagent. For the optimization of the nitrate determination μPAD, several variables associated with the design and construction of the device were studied. Furthermore, the interference of the urine matrix was evaluated, and stability studies were performed, under different conditions. The developed μPAD enabled us to obtain a limit of detection of 0.04 mM, a limit of quantification of 0.14 mM and a dynamic concentration range of 0.14–1.0 mM. The designed μPAD proved to be stable for 24 h when stored at room temperature in air or vacuum atmosphere, and 60 days when stored in vacuum at −20 °C. The accuracy of the nitrate μPAD measurements was confirmed by analyzing four certified samples (prepared in synthetic urine) and performing recovery studies using urine samples.

New microfluidic paper-based analytical device for iron determination in urine samples.

Iron is an important micronutrient involved in several mechanisms in the human body and can be an important biomarker. In this work, a simple and disposable microfluidic paper-based analytical device (µPAD) was developed for the quantification of iron in urine samples. The detection was based on the colorimetric reaction between iron(II) and bathophenanthroline and the reduction of iron(III) to iron(II) with hydroxylamine. The developed µPAD enabled iron determination in the range 0.07-1.2mg/L, with a limit of detection of 20µg/L and a limit of quantification of 65µg/L, thus suitable for the expected values in human urine. Additionally, targeting urine samples, the potential interference of the samples color was overcome by incorporating a sample blank assessment for absorbance subtraction. Stability studies revealed that the device was stable for 15days prior to usage and that the formed colored product was stable for scanning up to 3h. The accuracy of the developed device was established by analyzing urine samples (#26) with the developed µPAD and with the atomic absorption spectrometry method; the relative deviation between the two sets of results was below 9.5%.

A self-powered rotating paper-based analytical device for sensing of thrombin

We firstly constructed a kind of self-powered rotating paper-based microfluidic chip and used it to detect thrombin. The integrated movable valve has the ability to control the fluid user-friendly on microfluidic paper-based analytical devices (µPADs), and this advantage let it convenient to implement the complex multistep operations. In addition, this technique is compatible and versatile to the self-powered µPADs at differing levels of complexity. To obtain the supercapacitor signal, the DNA sequence (DNA1) and a glucose oxidase (GOx) modified DNA sequence (GOx-DNA2) were linked with aptamer to form the sandwich structure. Then thrombin will combine with its specific aptamer by strong binding ability, and the GOx-DNA2 could be released and to catalyze the oxidation of glucose. Because of GOx-triggered reaction, the voltage can be generated to charge the paper supercapacitor and its signal could be monitored by digital multimeter. The assay shows good performance with wide linear range (3–1350 nM) and the limit of detection for the thrombin assay was down to 0.9 nM. The proposed rotating paper-based aptamer device can integrate the complex self-powered multistep operations, and show good potential to be applied for on-site assay in the field of diagnosis.

3D printed hydrophobic barriers in a paper-based biosensor for point-of-care detection of dengue virus serotypes

Paper-based biosensor is one of the most commonly used platforms for point-of-care testing (POCT). Among these platforms, microfluidic paper-based analytical devices (μPADs) have the most versatile designs due to the different hydrophobic barrier patterns and layers of the devices. In addition, μPADs can also be used in combination with other biosensor platforms to improve the performance of the device. Simple and convenient methods for fabricating low-cost and design-adjustable hydrophobic barriers on paper are one of the most challenging aspects for creating μPADs. This work demonstrated a simple technique for using the common polylactic acid (PLA) filament and wax filament to create hydrophobic barriers on paper for μPADs using a commercialized 3D printer. As a proof of concept, the papers with 3D printed PLA barrier were used in combination with a fluidic chip in a prototype biosensor, in which the barrier paper housed four cell-free reactions and the fluidic chip achieved sample delivery to the reactions in the device. Our designed prototype was capable of discriminating dengue virus serotypes based on small nucleotide sequence differences. The proposed combination of 3D-printed barrier paper and fluidic chip provides a versatile platform for rapid prototyping of POCT with possible compatibility with various detection systems.

Microfluidic paper-based analytical device by using Pt nanoparticles as highly active peroxidase mimic for simultaneous detection of glucose and uric acid with use of a smartphone

Herein, a simple microfluidic paper-based analytical device (μPAD) by using platinum nanoparticles (Pt NPs) as highly active peroxidase mimic for simultaneous determination of glucose and uric acid was fabricated. The μPAD consisted of one sample transportation layer, four paper-based detection chips, and two layers of hydrophobic polyethylene terephthalate (PET) films. The four detection chips were immobilized with various chromogenic reagents, Pt NPs, and specific oxidase (glucose oxidase or uricase). H2O2 generated by specific enzymatic reactions could oxidize co-immobilized chromogenic reagents to produce colored products by using Pt NPs as efficient catalyst. The multi-layered structure of μPAD could effectively improve the color uniformity and color intensity. Total color intensity from each two detection chips modified with distinct chromogenic reagents were used for quantitative analysis of glucose and uric acid, respectively, resulting in significantly improved sensitivity. The linear range for glucose and uric acid detection was 0.01–5.0 mM and 0.01–2.5 mM, respectively. Satisfied results were obtained for glucose and uric acid detection in real serum samples. An easy-to-use smartphone APP was developed for convenient and intelligent detection. The developed μPAD integrated with smartphone as detector holds great applicability for simple and portable on-site analysis.

Reducing Unspecific Protein Adsorption in Microfluidic Papers Using Fiber-Attached Polymer Hydrogels.

Microfluidic paper combines pump-free water transport at low cost with a high degree of sustainability, as well as good availability of the paper-forming cellulosic material, thus making it an attractive candidate for point-of-care (POC) analytics and diagnostics. Although a number of interesting demonstrators for such paper devices have been reported to date, a number of challenges still exist, which limit a successful transfer into marketable applications. A strong limitation in this respect is the (unspecific) adsorption of protein analytes to the paper fibers during the lateral flow assay. This interaction may significantly reduce the amount of analyte that reaches the detection zone of the microfluidic paper-based analytical device (µPAD), thereby reducing its overall sensitivity. Here, we introduce a novel approach on reducing the nonspecific adsorption of proteins to lab-made paper sheets for the use in µPADs. To this, cotton linter fibers in lab-formed additive-free paper sheets are modified with a surrounding thin hydrogel layer generated from photo-crosslinked, benzophenone functionalized copolymers based on poly-(oligo-ethylene glycol methacrylate) (POEGMA) and poly-dimethyl acrylamide (PDMAA). This, as we show in tests similar to lateral flow assays, significantly reduces unspecific binding of model proteins. Furthermore, by evaporating the transport fluid during the microfluidic run at the end of the paper strip through local heating, model proteins can almost quantitatively be accumulated in that zone. The possibility of complete, almost quantitative protein transport in a µPAD opens up new opportunities to significantly improve the signal-to-noise (S/N) ratio of paper-based lateral flow assays.

Designing of various biosensor devices for determination of apoptosis: A comprehensive review

Apoptosis is a type of cell death caused by the occurrence of both pathological and physiological conditions triggered by ligation of death receptors outside the cell or triggered by DNA damage and/or cytoskeleton disruption. Timely monitoring of apoptosis can effectively help early diagnosis of related diseases and continuous assessment of the effectiveness of drugs. Detecting caspases, a protease family closely related to cellular apoptosis, and its identification as markers of apoptosis is a popular procedure. Biosensors are used for early diagnosis and play a very important role in preventing disease progression in various body sections. Recently, there has been a widespread increase in the desire to use materials made of paper (e.g. nitrocellulose membrane) for Point-of-Care (POC) testing systems since paper and paper-like materials are cheap, abundant and degradable. Microfluidic paper-based analytical devices (μPADs) are highly promising as they are cost-effective, easy to use, fast, precise and sustainable over time and under different environmental conditions. In this review, we focused our efforts on compiling the different approaches on identifying apoptosis pathway while giving brief information about apoptosis and biosensors. This review includes recent advantages in biosensing techniques to simply determine what happened in the cell life and which direction it would continue. As a conclusion, we believed that the review may help to researchers to compare/update the knowledge about diagnosis of the apoptosis pathway while reminding the basic definitions about the apoptosis and biosensor technologies.

Microfluidic paper device with on-site heating to produce reactive peroxide species for enhanced smartphone enabled chemiluminescence signal

Chemiluminescence signal amplification (CLSA) is of huge interest because of its sensitive detection in various applications such as food analysis, biomedical diagnosis and environmental monitoring. Due to this, there is a manifold attention to develop rapidly prototyped and miniaturized devices for CLSA. In this context, herein, a novel CLSA approach is demonstrated on a 3D printed microfluidic paper-based analytical device (μPADs), fabricated using Fused deposition modeling (FDM) printing technology. Influence of working temperature, ranging 30 °C–110 °C, on CL signal generation from well-established Luminol/Co+2 – H2O2 reaction was analyzed using a screen-printed flexible heater onto the 3D printed reaction platform. A smartphone-based capturing/detection system provided the amenability for a point-of-care testing system. For the first time, strong and stable CLSA was found with about 255% ± 5% increase in its signal intensity without using any additional external enhancers. The on-site working temperature was directly in proportional to the intensity of CL signal generated from Luminol/Co+2 – H2O2 reaction under optimum conditions, wherein the device had a wide linear range from 50 nM to 1 μM with a detection limit of 35 nM for H2O2 detection. The reliability of the developed amplification method was tested for practicability to detect the concentration of H2O2 in milk as real sample analysis. Overall, such CLSA mechanism in miniaturized μPADs will have strong potential for multiple CL based detection and monitoring application.

Fabrication for paper-based microfluidic analytical devices and saliva analysis application

Fabrication for paper-based microfluidic analytical devices and saliva analysis application

Phytochemical profile, antimicrobial, antioxidant activity and Cyclooxygenase 2 inhibitory properties of nutmeg (Myristica fragrans) seeds extract

The present study was conducted with the aim to extract phytochemical constituents of nutmeg (Myristica fragrans) seeds using methanol and acetone solvents, respectively by soxhlet apparatus with a yield of (1.47gm/100 gm) for methanol solvent and (2.11gm/100gm) for acetone solvent. The two extracts were tested for their antimicrobial, antioxidant and anti-inflammatory activities. Agar well diffusion method was adopted against four bacterial species including two Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis) and two Gram-negative bacteria (Escherichia coli, and Klebsiella sp.) as well as one yeast (Candida albicans) to determine the antimicrobial activity. The present study showed that the tested microorganisms were inhibited by nutmeg acetone extract with an inhibition zone ranging between (11-15 mm), especially toward Candida albicans with 15 mm diameter while no inhibition zone was observed using methanol extract. Chemical constituents of nutmeg acetone extract were estimated using Atomic Absorption Spectrometry (AAS) and Gas Chromatography-Mass Spectroscopy (GC-MS) measurements revealed the presence of 150 µg/dl Cu, 280 µg/dl Zn, 6.1 µg/dl Pb, 0.08 µg/dl Cd, 0.09 µg/dl Cr, 0.0012 µg/dl Ni and 0.027 µg/dl Mn and 32 extra compounds. Other phytochemical detections including alkaloids, tannins, terpenoid, saponins, glycosides, resins, and flavonoids were investigated using standard procedures. Total phenol content and radical scavenging activity were measured quantitatively using Folin-Ciocalteu and 2,2-diphenylpicrylhydrazyl (DPPH) methods, respectively and were compared qualitatively with the microfluidic paper-based analytical device (µPADs) as a new platform. The extract contains a high concentration of phenolic compounds (0.6217 mg/ml) and the DPPH assay for acetone extract indicated a high amount of antioxidant compounds. The effect of nutmeg acetone extract on cyclooxygenase (COX-2) enzyme activity has been done and showed that the nutmeg extract can inhibit COX-2 activity better than the ability of anti-inflammatory drug (Aspirin). Our findings indicate the potential use of nutmeg acetone extract as a source of antimicrobial, antioxidant, and anti-inflammatory agent.

Paperfluidic devices with a selective molecularly imprinted polymer surface for instrumentation-free distance-based detection of protein biomarkers

Microfluidic paper-based analytical devices (μPADs) offer the advantages of simplicity, extremely low costs, robustness, and miniaturisation, synergistically supporting portability and point-of-care (POC) analysis. When μPADs are combined with distance-based detection in DμPADs, they uniquely enable a quantitative analytical platform that is truly instrumentation-free (naked-eye readout), or at least, does not require any specialised scientific instrumentation (only mobile phone camera). However, a significant drawback of DμPADs is their limited selectivity. In this work, we present for the first time molecularly imprinted polymer (MIP) as a selectivity-enhancing element in MIP-modified DμPADs (MIP-DμPADs). Herein, a layer of polydopamine MIP was coated onto the paper substrate of a DμPAD, in a simple process using dopamine as the monomer deposited onto the paper matrix in the migration-detection zone of the DμPAD, and polymerised in a rapid low cost procedure in the presence of oxygen under alkaline conditions. The polydopamine MIP-DμPAD was then systematically investigated for the selective determination of chymotrypsinogen (chymo) as a model protein biomarker in urine, within the linear concentration range 2.4–29.2 μM (R2 = 0,9903) with corresponding relative standard deviations ranging from 2% to 11 % and LOD =3.5 μM and LOQ =11.8 μM. The here presented analytical concept based on MIP-DμPADs has a potential in POC diagnostics, because of the combination of low cost automated fabrication, the rapid quantitative near to instrumentation-free analysis, and selectivity through the use of MIPs as a synthetic, more stable, cheaper and easily prepared alternative to bio-macromolecules.

Transmittance measurements on paper soaked with deep eutectic solvents

This investigation was carried out with the aim of verifying whether transmittance detection modes on soaked paper, which is a simple and attractive determination approach for microfluidic paper-based analytical devices, can be improved by using deep eutectic solvents (DESs) as suitable media for minimizing reflection and refraction phenomena affecting these measurements. With this purpose, we tested two DESs such as ethaline and glyceline by checking that paper soaked with both two DESs displayed a quite higher transparency than that soaked with water (the absorbance decreased of about 25%). This result is particularly important in that DESs offer the appreciable advantage of being characterized by a negligible vapor pressure, unlike water or the majority of organic media, thus allowing long-term detections or analysis of very small samples to be conducted avoiding any problem caused by the solvent evaporation. As a proof of concept, we have then compared the detection of the patent blue V dye (E131) in ethaline solutions with that of the same dye dissolved in water. These determinations were performed on paper discs defined by a circular hydrophobic barrier which were installed into a plastic holder, which was constructed on purpose by the 3D technology to fit the cell housing of a Varian Cary 50 bio benchtop spectrophotometer adopted in our spectrophotometric measurements. The results found on paper discs soaked with ethaline were totally satisfactory in that they were characterized by a good repeatability and allowed a calibration plot to be constructed in a quite wide concentration range which allowed quite low concentrations to be detected (in the µM range) and was characterized by a good enough correlation coefficient. On the contrary, the results found on paper discs soaked with water were totally unsatisfactory since they were strongly affected by both the solvent evaporation and a more marked ripple present in the recorded spectra.

Application of microfluidic paper-based analytical device (μPAD) to detect COVID-19 in energy deprived countries.

SummaryCoronavirus disease (COVID‐19) has spread all across the world. Low‐ and medium‐income countries are more affected economically and socially compared to developed countries due to the lack of a rapid, robust, and affordable testing infrastructure. Furthermore, the high cost of real‐time polymerase chain reaction (PCR) system, sophisticated user‐handling procedure, and high expense of the conventional clinical tests are the root causes of the less accessibility of the testing systems to the users. In this study, a COVID‐19 Point‐of‐Care (POC) ecosystem model is proposed for the low‐ and medium‐income countries (or energy deprived countries) that will facilitate the technological development with locally available fabrication components. In addition, the nontechnological development phases have also been discussed, which encompasses the collaboration among academia, local as well as government bodies, and entrepreneurial ventures. In addition, a hypothetical design of a microfluidic paper‐based analytical (μPADs) POC platform is proposed to detect COVID‐19 analyte using unprocessed patient‐derived saliva, which is a miniaturized form‐factor of conventional real‐time polymerase chain reaction (PCR) technique. The device contains four major reaction zones, which are sample zone, buffer zone, loop‐mediated isothermal amplification (LAMP) Master Mix zone, Ethylenediamine tetraacetic acid (EDTA) zone, and sensor zone. To obtain quicker test results and easier operation, a handheld image acquisition technique is introduced in this study. It is hypothesized that in a remote setting, the proposed design could be used as an initial guideline to develop a POC COVID‐19 testing system, which may be simple, easy‐to‐use, and cost‐effective.

Regression Analysis of Orthogonal, Cylindrical and Multivariable Color Parameters for Colorimetric Surface pH Measurement of Materials

The surface pH is a critical factor in the quality and longevity of materials and products. Traditional fast colorimetric pH detection-based tests such as water quality control or pregnancy tests, when results are determined by the naked eye, cannot provide quantitative values. Using standard pH papers, paper-printed comparison charts, or colorimetric microfluidic paper-based analytical devices is not suitable for such technological applications and quality management systems (QMSs) where the particular tested material should contain a suitable indicator in situ, in its structure, either before or after the process, the technology or the apparatus that are being tested. This paper describes a method based on the combination of impregnation of a tested material with a pH indicator in situ, its exposure to a process of technology whose impact on pH value is to be tested, colorimetric pH measurement, and approximation of pH value using derived pH characteristic parameters (pH-CPs) based on CIE orthogonal and cylindrical color variables. The hypotheses were experimentally verified using the methyl red pH indicator, impregnating the acid lignin-containing paper, and preparing a calibration sample set with pH in the range 4 to 12 using controlled alkalization. Based on the performed measurements and statistical evaluation, it can be concluded that the best pH-CPs with the highest regression parameters for pH are √∆E, ln (a), √∆H (ab), a/L, h/b and ln (b/a). The experimental results show that the presented method allows a good estimation of pH detection of the material surfaces.

Microfluidic Paper-Based Analytical Devices: From Design to Applications.

Microfluidic paper-based analytical devices (μPADs) have garnered significant interest as a promising analytical platform in the past decade. Compared with traditional microfluidics, μPADs present unique advantages, such as easy fabrication using established patterning methods, economical cost, ability to drive and manipulate flow without equipment, and capability of storing reagents for various applications. This Review aims to provide a comprehensive review of the field, highlighting fabrication methods available to date with their respective advantages and drawbacks, device designs and modifications to accommodate different assay needs, detection strategies, and the growing applications of μPADs. Finally, we discuss how the field needs to continue moving forward to realize its full potential.

A New Direction in Microfluidics: Printed Porous Materials.

In this work, the feasibility of a novel direction for microfluidics is studied by demonstrating a set of new methods to fabricate microfluidic systems. Similarly to microfluidic paper-based analytical devices, porous materials are being used. However, alternative porous materials and different printing methods are used here to give the material the necessary pattern to act as a microfluidic system. In this work, microfluidic systems were produced by the following three separate methods: (1) by curing a porous monolithic polymer sheet into a necessary pattern with photolithography, (2) by screen printing silica gel particles with gypsum, and (3) by dispensing silica gel particles with polyvinyl acetate binder using a modified 3D printer. Different parameters of the printed chips were determined (strength of the printed material, printing accuracy, printed material height, wetting characteristics, repeatability) to evaluate whether the printed chips were suitable for use in microfluidics. All three approaches were found to be suitable, and therefore the novel approach to microfluidics was successfully demonstrated.