Microfluidic Array Research Articles

Development of a multitissue microfluidic array for assessing changes in gene expression associated with channel catfish appetite, growth, metabolism, and intestinal health

Large-scale, gene expression profiling methods allow for high throughput analysis of physiological pathways at a fraction of the cost of individual gene expression analysis. Systems, such as the Fluidigm quantitative PCR array described here, can provide powerful assessments of the effects of diet, environment, and management on physiological pathways affecting production parameters. A targeted microfluidic PCR array was designed and validated, for channel catfish (Ictalurus punctatus) representing key pathways involved in appetite, growth, metabolism, and intestinal inflammation for their potential to provide insight into the effects of diet and dietary supplements on these important physiological processes regulating feed efficiency and growth. With few exceptions, PCR primers were designed from Ictaluridae gene sequences published in GenBank. PCR amplicons from primers designed outside of Ictaluridae were sequenced to verify gene identity. All target gene primers were initially validated via conventional real-time qPCR (RT-qPCR). Combined hypothalamus/pituitary, hepatic, stomach, and intestinal tissue were used validate a 48.48 microfluidic PCR array to analyze multitissue gene expression. Use of the Fluidigm array resulted in reliable cycle threshold levels (Ct), efficiencies (E), and quality threshold scores (QS) for all but eight genes examined. Of the potential reference genes included in the panel, alpha-tubulin (TUBA) had a high QS, E, and acceptable Ct. The high throughput application of this technology, relative to conventional RT-qPCR, for assessing dietary effects on these pathways is demonstrated. Development of this targeted multi-tissue microfluidic array paves the way for the rapid evaluation of regulatory pathways in response to alternative feeding strategies, dietary formulations, and supplementation, as well as environmental and management effects for improving channel catfish culture and validates a cost-effective, dynamic, gene expression platform for use with other cultured fishes.

The characterization of a low-profile channel–confined jet for targeted hot-spot cooling in microfluidic applications

Photonics Integrated Circuits (PICs) are the backbone of the optical-fiber networks that enable high-speed communication on a global scale. Contemporary devices contain laser-bars (∼μm length-scale) which must be controlled within ±0.1K, and are capable of generating heat fluxes ∼1kW/m2. This represents one of the highest heat fluxes found in nature or engineering applications, and the thermal challenge places a limitation on the density of laser-bar arrays on an individual chip. Chip-integrated μfluidic cooling has been proposed for the thermal management of next-generation PICs to create more energy efficient devices, capable of greater data throughput. Jet impingements are of interest as the primary heat exchangers in this system due to the large heat transfer rates that can be achieved. The objective of this work is to generate a novel, low profile jet impingement within an individual channel suitable for targeting hot-spots in a densely packed circuit, at the low Reynolds numbers prevalent in micro-fluidic applications (Re<500). To this end, two experiments were performed to non-invasively observe the velocity field and local heat transfer in a square miniature channel containing a curved orifice-plate to manipulate the fluid flow. A range of Reynolds numbers (channel Re=100−200) and obstruction opening area ratios (β=0.2−0.5) were investigated through Particle-Image Velocimetry and infrared thermography of a Joule-heated foil. The velocimetry data showed that the curved orifice-plate geometry successfully generated an inclined jet within the channel, and maximum improvements in the area-averaged heat transfer coefficient of 495% (relative to a channel containing no obstruction) were measured. The heat transfer data showed Nu∼Re0.59scaling, similar to that of a micro-fluidic array of normally impinging jets, and this physical relationship is beneficial in the design and modeling of μfluidic cooling systems. The findings illustrate the impact of a channel confined jet on spatial heat transport, and demonstrate the potential for controlled heat transfer enhancement using unconventional obstructions within laminar channel flows.

Microfluidic Array Chip with Parallel Channels for Fast Preparation of Sample Droplet Array.

We present a parallel microfluidic array chip for the fast preparation of microdroplets to provide droplet arrays of a sample using the hydrodynamics of immiscible fluids as they flow in a microchamber and bypass channel. The microfluidic chip has eight channels that are parallel from the inlet to the outlet of the device. Each channel has 13 microchambers and bypass channels to trap the droplets from the sample plugs. Because samples can be arrayed simultaneously in eight parallel channels, the arrays of sample droplets can form quickly. After filling the microchannel and chambers with the sample, oil is injected into the device. As the oil fills the microchannel, owing to the difference in the flow resistance between the microchamber and bypass channel, the oil flows through the bypass channel, trapping the sample in the microchamber. A total of 104 microdroplets of an aqueous sample could be successfully trapped in 8 x 13 arrays of microchambers using one simple injection of sequential plugs of mineral oil, the aqueous sample, and mineral oil with surfactant. Sample droplets were successfully formed at all chambers at flow rates of less than 0.06 mL/h, and a trapping efficiency of greater than 90% was achieved at 0.15 mL/h.

Automatic Combination of Microfluidic Nanoliter-Scale Droplet Array with High-Speed Capillary Electrophoresis.

In this paper, we developed a novel approach for interfacing a microfluidic two-dimensional droplet array to a high-speed capillary electrophoresis (HSCE) system. Picoliter-scale sample injection (ca. 200 pL) from a nanoliter-scale droplet array covered by nonvolatile oil was automatically achieved using the spontaneous injection mode, without the interference from the cover oil and the need of special droplet extraction interface as in previously reported systems. The system was applied in consecutive separations of 25 different samples of amino acids with a whole separation time less than 15 min, as well as on-line monitoring of in-droplet derivatizing reaction of amino acids by fluorescein isothiocyanate (FITC) over 3 hours. High separation speed (up to 100 samples per hour) and high separation efficiency (up to 9.22 × 105 N/m) were achieved.

Label-Free Digital Quantification of Lipid Droplets in Single Cells by Stimulated Raman Microscopy on a Microfluidic Platform.

Quantitative characterization of a single-cell phenotype remains challenging. We combined a scalable microfluidic array of parallel cell culture chambers and stimulated Raman scattering (SRS) microscopy to quantitatively characterize the response of lipid droplet (LD) formation to free-fatty-acid stimuli with single-LD resolution at the single-cell level. By enabling the systematic live-cell imaging with SRS microscopy in a microfluidic device, we were able to quantify the morphology of over a thousand live cells in 10 different chemical environments and with 8 replicates for each culture condition, in a single experiment, and without relying on fluorescent labeling. We developed an image processing pipeline for cell segmentation and LD morphology quantification using dual-channel SRS images. This allows us to construct distributions of the morphological parameters of LDs in the cellular population and expose the vast phenotypic heterogeneity among genetically similar cells. Specifically, this approach provides an analytical tool for quantitatively investigating LD morphology in live cells in situ. With this high-throughput, high-resolution, and label-free method, we found that LD growth dynamics showed considerable cell to cell variation. Lipid accumulation in nonadipocyte cells is mainly reflected in the increase of LD number, as opposed to an increase in their size or lipid concentration. Our method allows statistical single-cell quantification of the LD distribution for further investigation of lipid metabolism and dynamic behavior, and also extends the possibility to couple with other "omics" technologies in the future.

Pathogen receptor discovery with a microfluidic human membrane protein array

The discovery of how a pathogen invades a cell requires one to determine which host cell receptors are exploited. This determination is a challenging problem because the receptor is invariably a membrane protein, which represents an Achilles heel in proteomics. We have developed a universal platform for high-throughput expression and interaction studies of membrane proteins by creating a microfluidic-based comprehensive human membrane protein array (MPA). The MPA is, to our knowledge, the first of its kind and offers a powerful alternative to conventional proteomics by enabling the simultaneous study of 2,100 membrane proteins. We characterized direct interactions of a whole nonenveloped virus (simian virus 40), as well as those of the hepatitis delta enveloped virus large form antigen, with candidate host receptors expressed on the MPA. Selected newly discovered membrane protein-pathogen interactions were validated by conventional methods, demonstrating that the MPA is an important tool for cellular receptor discovery and for understanding pathogen tropism.

Induction of Human iPSC-Derived Cardiomyocyte Proliferation Revealed by Combinatorial Screening in High Density Microbioreactor Arrays.

Inducing cardiomyocyte proliferation in post-mitotic adult heart tissue is attracting significant attention as a therapeutic strategy to regenerate the heart after injury. Model animal screens have identified several candidate signalling pathways, however, it remains unclear as to what extent these pathways can be exploited, either individually or in combination, in the human system. The advent of human cardiac cells from directed differentiation of human pluripotent stem cells (hPSCs) now provides the ability to interrogate human cardiac biology in vitro, but it remains difficult with existing culture formats to simply and rapidly elucidate signalling pathway penetrance and interplay. To facilitate high-throughput combinatorial screening of candidate biologicals or factors driving relevant molecular pathways, we developed a high-density microbioreactor array (HDMA) – a microfluidic cell culture array containing 8100 culture chambers. We used HDMAs to combinatorially screen Wnt, Hedgehog, IGF and FGF pathway agonists. The Wnt activator CHIR99021 was identified as the most potent molecular inducer of human cardiomyocyte proliferation, inducing cell cycle activity marked by Ki67, and an increase in cardiomyocyte numbers compared to controls. The combination of human cardiomyocytes with the HDMA provides a versatile and rapid tool for stratifying combinations of factors for heart regeneration.

Ultrafast laser ablation of soda-lime glass for fabricating microfluidic pillar array channels

Microfluidic devices constitute the key technology enabling the development of more functional lab-on-a-chip systems for medical applications. This study presents an alternative method for precisely fabricating microfluidic pillar array channels by using irradiation by an ultrashort pulse from an ultrafast laser. Unlike conventional photolithography, which requires complex procedures and techniques, the ultrafast laser process is a straightforward approach for fabricating a functional microfluidic device with multiple pulses of an ultraviolet (UV) wavelength. To satisfy the requirements of the industrial process for mass production of microfluidic devices, a picosecond (PS) laser is used as a light source. Under the optimal energy fluence of 15.28J/cm2 with a pulse overlap of 95%, the scanning curve process can be executed in the clockwise direction for forming microfluidic pillar array structures. Simultaneously, the experimental evidence shows that the ultrafast laser process produces ablated soda-lime glass channels with hydrophilic surfaces on their inner walls. Based on the processing parameters of pillar structure with the number of pulses, the value of ablation rate can be 0.04μm/pulse. This work provides a direct patterning process through which a pillar array with functional structures can be constructed within the microfluidic device.

Abstract B32: Longitudinal changes in plasma miRNA in patients with benign and malignant colorectal neoplasia

Abstract Introduction: The adenoma-carcinoma sequence is well-recognized as a stepwise pattern of mutational activation of oncogenes and inactivation of tumor suppressor genes resulting in sporadic colorectal cancer (CRC) development from colorectal adenomas (CRA) within the chromosomal instability pathway. MicroRNAs (miRNA) play an important role in oncogenesis by regulating gene expression and are known to be actively released from cells. They are found in body fluids such as plasma, saliva, feces and urine. We have previously demonstrated differential expression of plasma miRNAs in patients with CRC as compared to that of controls. Methods: Plasma was isolated from 10 patients: 5 patients with advanced colorectal adenoma (&amp;gt;0.6cm diameter) and 5 patients with stage II or III colorectal cancer prior to treatment and 4-6 weeks following endoscopic removal or surgical resection, respectively. RNA was extracted from plasma (Qiagen® miRNeasy), RT-PCR performed and 768 miRNAs were screened using microfluidic array technology (Applied BioSystems®) in pre- and post-treatment samples for each patient. Data were analyzed using paired t-tests after normalizing raw cycle threshold data to endogenous RNU6 for pre- and post-treatment samples. In addition, miRNA expression data from both pre- and post-treatment CRA and CRC samples were compared to that of plasma from 10 individuals without neoplasia (controls) (ANOVA). Results: Significant differential expression of plasma miRNAs was observed between pre- and post-treatment samples in both CRA and CRC groups. Interestingly, there was generalized miRNA upregulation in CRA when comparing pre-treatment samples to post-treatment samples. Conversely there was miRNA down-regulation in pre-treatment CRC plasma as compared to post-resection samples. Utilizing significantly dysregulated miRNAs, as well as p-values, AUC, fold-change and biological significance, miRNA panels were selected to facilitate detection of CRA recurrence (following complex polypectomy for large polyps) or for detection of recurrent CRC following resection. The resulting panel was able to differentiate between pre- and post-treatment samples for CRA (miR-186 and miR-623) with AUC 0.94 (95% CI 0.76 – 1.00) and for CRC (miR-324-5p, miR-30d and miR-766) with AUC 0.88 (95% CI 0.63 – 1.00). In addition, while miRNA expression of pre-treatment CRA and CRC samples differed significantly from controls, post-treatment CRA and CRC samples did not. Conclusion: Comparison of pre- and post-treatment plasma samples reveals differing patterns of changes in miRNA expression in benign colorectal neoplasms (CRA) as opposed to invasive neoplasia (CRC). The observed miRNA down-regulation prior to surgical resection of CRC might indicate decreased expression of miRNAs inhibiting oncogenes prior to cancer treatment, while the miRNA upregulation seen in pre-treatment CRA plasma could indicate inhibition of tumor suppressors. Such observations will perhaps elucidate the role of miRNA in carcinogenesis and may provide for a relatively non-invasive method of detecting such lesions. Further validation is needed to develop a miRNA panel that will allow monitoring for evidence of recurrent disease. Citation Format: Jane Carter, Vanessa States, Uri Netz, Jianmin Pan, Shesh Rai, Susan Galandiuk. Longitudinal changes in plasma miRNA in patients with benign and malignant colorectal neoplasia. [abstract]. In: Proceedings of the AACR Special Conference on Noncoding RNAs and Cancer: Mechanisms to Medicines ; 2015 Dec 4-7; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2016;76(6 Suppl):Abstract nr B32.

Disposable microfluidic sensor arrays for discrimination of antioxidants

A microfluidic colorimetric sensor array was developed for detection and identification of various antioxidants. The sensor was fabricated by a photolithographic method, and consists of an array of printed cross-responsive indicators. The microfluidic design also incorporates pre-activation spots to allow printing of chemically incompatible components separately. Separately printed oxidizer allowed an oxidation of adjacent redox indicators only when aqueous sample was added to the sensor cartridge. Antioxidants were primarily detected by measuring the extent of inhibition of this oxidation reaction. Using this flow-based technique, a clear differentiation of 8 different antioxidants and 4 different teas has been demonstrated with 98.5% sensitivity.

A portable paper-based microfluidic platform for multiplexed electrochemical detection of human immunodeficiency virus and hepatitis C virus antibodies in serum.

This paper presents a portable paper-based microfluidic platform for multiplexed electrochemical detection of antibody markers of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) in serum samples. To our best knowledge, this is the first paper-based electrochemical immunosensing platform, with multiplexing and telemedicine capabilities, for diagnosing HIV/HCV co-infection. The platform consists of an electrochemical microfluidic paper-based immunosensor array (E-μPIA) and a handheld multi-channel potentiostat, and is capable of performing enzyme-linked immunosorbent assays simultaneously on eight samples within 20 min (using a prepared E-μPIA). The multiplexing feature of the platform allows it to produce multiple measurement data for HIV and HCV markers from a single run, and its wireless communication module can transmit the results to a remote site for telemedicine. The unique integration of paper-based microfluidics and mobile instrumentation renders our platform portable, low-cost, user-friendly, and high-throughput.

Don't put all your eggs in one basket: a cost-effective and powerful method to optimize primer choice for rRNA environmental community analyses using the Fluidigm Access Array.

With the increasing democratization of high-throughput sequencing (HTS) technologies, along with the concomitant increase in sequence yield per dollar, many researchers are exploring HTS for microbial community ecology. Many elements of experimental design can drastically affect the final observed community structure, notably the choice of primers for amplification prior to sequencing. Some targeted microbes can fail to amplify due to primer-targeted sequence divergence and be omitted from obtained sequences, leading to differences among primer pairs in the sequenced organisms even when targeting the same community. This potential source of taxonomic bias in HTS makes it prudent to investigate how primer choice will affect the sequenced community prior to investing in a costly community-wide sequencing effort. Here, we use Fluidigm's microfluidic Access Arrays (IFC) followed by Illumina(®) MiSeq Nano sequencing on a culture-derived local mock community to demonstrate how this approach allows for a low-cost combinatorial investigation of primer pairs and experimental samples (up to 48 primer pairs and 48 samples) to determine the most effective primers that maximize obtained communities whilst minimizing taxonomic biases.

Rapid identification of ubiquitination and SUMOylation target sites by microfluidic peptide array

SUMOylation and ubiquitination are two essential post translational modifications (PTMs) involved in the regulation of important biological processes in eukaryotic cells. Identification of ubiquitin (Ub) and small ubiquitin-related modifier (SUMO)-conjugated lysine residues in proteins is critical for understanding the role of ubiquitination and SUMOylation, but remains experimentally challenging. We have developed a powerful in vitro Ub/SUMO assay using a novel high density peptide array incorporated within a microfluidic device that allows rapid identification of ubiquitination and SUMOylation sites on target proteins. We performed the assay with a panel of human proteins and a microbial effector with known target sites for Ub or SUMO modifications, and determined that 80% of these proteins were modified by Ub or specific SUMO isoforms at the sites previously determined using conventional methods. Our results confirm the specificity for both SUMO isoform and individual target proteins at the peptide level. In summary, this microfluidic high density peptide array approach is a rapid screening assay to determine sites of Ub and SUMO modification of target substrates, which will provide new insights into the composition, selectivity and specificity of these PTM target sites.

A Novel Multi-Layer Microfluidic Pipette Aspiration Device for Studying Mechanosensitive Vesicles

Mechanosensitive channel of large conductance (MscL) is a prokaryotic channel that opens due to increased membrane tension. It has been reconstituted in vesicles to study how various biophysical factors influence their mechanical gating properties. In recent years, several theoretical and computational models based on molecular dynamics and continuum mechanics have been developed to understand the underlying mechanisms for the activation of MscLs in vesicles. Experimental approaches for MscL gating studies have focused on cell-by-cell techniques, such as pressure patch clamp, on reconstituted MscL vesicles. Due to the limitation of throughput, such studies are time intensive with low sample numbers. Recently, a microfluidic pipette aspiration array device, based on PDMS multi-layer soft-lithography technique, has been developed in our group to trap and apply mechanical perturbation to single cells in a parallel manner1. This device was used to study the stiffness of human breast cancer cell lines and mechanical gating threshold of reconstituted MscL on infected mammalian cell lines. In this work, we have developed a new device that incorporates a pressure valve and a smaller micropipette dimension to increase trapping efficiency of vesicles. Using this device, we demonstrate stable trapping of single vesicles and expand our efforts to study mechanical gating threshold of reconstituted MscL in vesicles formed by electroformation. Development of novel microtechnology tools that can trap single vesicles and exert tension will have numerous applications to the study of other mechanosensitive channels.[1] Lee & Liu, Lab Chip, 2015, 15, 264-273.

Mutual capacitance of liquid conductors in deformable tactile sensing arrays

Advances in highly deformable electronics are needed in order to enable emerging categories of soft computing devices ranging from wearable electronics, to medical devices, and soft robotic components. The combination of highly elastic substrates with intrinsically stretchable conductors holds the promise of enabling electronic sensors that can conform to curved objects, reconfigurable displays, or soft biological tissues, including the skin. Here, we contribute sensing principles for tactile (mechanical image) sensors based on very low modulus polymer substrates with embedded liquid metal microfluidic arrays. The sensors are fabricated using a single-step casting method that utilizes fine nylon filaments to produce arrays of cylindrical channels on two layers. The liquid metal (gallium indium alloy) conductors that fill these channels readily adopt the shape of the embedding membrane, yielding levels of deformability greater than 400%, due to the use of soft polymer substrates. We modeled the sensor performance using electrostatic theory and continuum mechanics, yielding excellent agreement with experiments. Using a matrix-addressed capacitance measurement technique, we are able to resolve strain distributions with millimeter resolution over areas of several square centimeters.

On-chip analysis, indexing and screening for chemical producing bacteria in a microfluidic static droplet array.

Economic production of chemicals from microbes necessitates development of high-producing strains and an efficient screening technology is crucial to maximize the effect of the most popular strain improvement method, the combinatorial approach. However, high-throughput screening has been limited for assessment of diverse intracellular metabolites at the single-cell level. Herein, we established a screening platform that couples a microfluidic static droplet array (SDA) and an artificial riboswitch to analyse intracellular metabolite concentration from single microbial cells. Using this system, we entrapped single Escherichia coli cells in SDA to measure intracellular l-tryptophan concentrations. It was validated that intracellular l-tryptophan concentration can be evaluated by the fluorescence from the riboswitch. Moreover, high-producing strains were successfully screened from a mutagenized library, exhibiting up to 145% productivity compared to its parental strain. This platform will be widely applicable to strain improvement for diverse metabolites by developing new artificial riboswitches.

Deformability measurement of red blood cells using a microfluidic channel array and an air cavity in a driving syringe with high throughput and precise detection of subpopulations.

Red blood cell (RBC) deformability has been considered a potential biomarker for monitoring pathological disorders. High throughput and detection of subpopulations in RBCs are essential in the measurement of RBC deformability. In this paper, we propose a new method to measure RBC deformability by evaluating temporal variations in the average velocity of blood flow and image intensity of successively clogged RBCs in the microfluidic channel array for specific time durations. In addition, to effectively detect differences in subpopulations of RBCs, an air compliance effect is employed by adding an air cavity into a disposable syringe. The syringe was equally filled with a blood sample (V(blood) = 0.3 mL, hematocrit = 50%) and air (V(air) = 0.3 mL). Owing to the air compliance effect, blood flow in the microfluidic device behaved transiently depending on the fluidic resistance in the microfluidic device. Based on the transient behaviors of blood flows, the deformability of RBCs is quantified by evaluating three representative parameters, namely, minimum value of the average velocity of blood flow, clogging index, and delivered blood volume. The proposed method was applied to measure the deformability of blood samples consisting of homogeneous RBCs fixed with four different concentrations of glutaraldehyde solution (0%-0.23%). The proposed method was also employed to evaluate the deformability of blood samples partially mixed with normal RBCs and hardened RBCs. Thereafter, the deformability of RBCs infected by human malaria parasite Plasmodium falciparum was measured. As a result, the three parameters significantly varied, depending on the degree of deformability. In addition, the deformability measurement of blood samples was successfully completed in a short time (∼10 min). Therefore, the proposed method has significant potential in deformability measurement of blood samples containing hematological diseases with high throughput and precise detection of subpopulations in RBCs.

Microfluidic array for simultaneous detection of DNA oxidation and DNA-adduct damage.

Exposure to chemical pollutants and pharmaceuticals may cause health issues caused by metabolite-related toxicity. This paper reports a new microfluidic electrochemical sensor array with the ability to simultaneously detect common types of DNA damage including oxidation and nucleobase adduct formation. Sensors in the 8-electrode screen-printed carbon array were coated with thin films of metallopolymers osmium or ruthenium bipyridyl-poly(vinylpyridine) chloride (OsPVP, RuPVP) along with DNA and metabolic enzymes by layer-by-layer electrostatic assembly. After a reaction step in which test chemicals and other necessary reagents flow over the array, OsPVP selectively detects oxidized guanines on the DNA strands, and RuPVP detects DNA adduction by metabolites on nucleobases. We demonstrate array performance for test chemicals including 17β-estradiol (E2), its metabolites 4-hydroxyestradiol (4-OHE2), 2-hydroxyestradiol (2-OHE2), catechol, 2-nitrosotoluene (2-NO-T), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and 2-acetylaminofluorene (2-AAF). Results revealed DNA-adduct and oxidation damage in a single run to provide a metabolic-genotoxic chemistry screen. The array measures damage directly in unhydrolyzed DNA, and is less expensive, faster, and simpler than conventional methods to detect DNA damage. The detection limit for oxidation is 672 8-oxodG per 106 bases. Each sensor requires only 22 ng of DNA, so the mass detection limit is 15 pg (∼10 pmol) 8-oxodG.

Solvent compatible microfluidic platforms for pharmaceutical solid form screening

The use of SIFEL in the crystallization fluid layers renders the microfluidic crystallization array compatible with solvents such as tetrahydrofuran, acetonitrile, chloroform, hexane, and toluene.

Electrochemistry-based approaches to low cost, high sensitivity, automated, multiplexed protein immunoassays for cancer diagnostics.

Early detection and reliable diagnostics are keys to effectively design cancer therapies with better prognoses. The simultaneous detection of panels of biomarker proteins holds great promise as a general tool for reliable cancer diagnostics. A major challenge in designing such a panel is to decide upon a coherent group of biomarkers which have higher specificity for a given type of cancer. The second big challenge is to develop test devices to measure these biomarkers quantitatively with high sensitivity and specificity, such that there are no interferences from the complex serum or tissue matrices. Lastly, integrating all these tests into a technology that does not require exclusive training to operate, and can be used at point-of-care (POC) is another potential bottleneck in futuristic cancer diagnostics. In this article, we review electrochemistry-based tools and technologies developed and/or used in our laboratories to construct low-cost microfluidic protein arrays for the highly sensitive detection of a panel of cancer-specific biomarkers with high specificity which at the same time has the potential to be translated into POC applications.