Inside the microfluidic LoC are channels of different sizes, reservoirs, reagents, pumps and valves, sensors, and detection mechanisms to read the output of the reactions. A LoC can be made by molded plastics or laminates, and produced in large quantities. This enables low-cost diagnostic testing with high-throughput, clinically acceptable results in 15-20 minutes.
Here are my top five high-impact applications for microfluidic diagnostic devices with a description of current activities and my rationale for their selection.
1. Infectious Disease
A microfluidic cartridge test kit for Infectious diseases detection is on top of the list. There are several companies in the U.S., Canada, and Europe commercializing tests for Flu A, B, and other infectious diseases. Their cartridges provide fast and effective diagnostics tools in the clinic and at home. Having such diagnostics tools at PoC will help control the spread of infectious disease within the community, provide timely treatment, and effectively manage patients.
One commercially available microfluidic chip uses a thermoplastic material integrated with channels, reservoirs, and reagents and has the ability to amplify influenza A virus using nasopharyngeal (NP) swabs and aspirates in the patient. A sample from the swabs is loaded into the microfluidic device and stripped of the target materials, including cells. The chip then sequentially performs on-chip cell lysis, RNA purification, and concentration steps within the solid phase extraction (SPE), and reverse transcription (RT) and polymerase chain reaction (PCR) in RT-PCR chambers. After the processes are completed, the end product goes to a reader to determine final output.
Another interesting LoC integrates 12 silicon disposable arrays that can detect proteins or antibodies when they bind to the sensors in real-time. It has the ability to potentially perform 128 different tests on a single finger prick of blood in 15-20 minutes. Currently in the pre-clinical testing stage, the platform will significantly improve infectious disease diagnostics when it is commercialized.
Home testing or self-test cartridges are also available and reported to be capable of testing for flu, bacterial infections, and even cancer. Recently, such a device began being used with cancer patients to monitor white blood cell counts for chemotherapy.
Yet another LoC captures high-resolution images from a single drop of blood inside the microfluidic channel and uses a computer algorithm to tag and count the cells. The process relies on machine learning, a form of artificial intelligence trained to analyze thousands of images of blood cells.
2. Autoimmune Disease
Our body makes antibodies to attack and destroy substances such as bacteria and viruses. But in autoimmune diseases, the antibodies attack and destroy body tissues instead of the foreign objects. This can lead to diseases such as rheumatoid arthritis, scleroderma, and lupus. These health problems also affect the connective tissues, such as the skin and joints, blood vessels, and other tissues. A microfluidic chip was recently developed to detect autoimmune diseases. The device measures the number of specified antibodies in the blood.
A group of university researchers developed an in vitro system that detects autoantibodies using a photo immobilized autoantigen microarray. In their device, they used a microfluidic array spotted with aqueous solutions of autoantigen mixed with a polymer and a photoreactive crosslinker. In their assay, patient serum was added to the microarray plate. The antigen-specific IgG absorbed on the micro spotted autoantigen was detected by peroxidase-conjugated anti-IgG antibody. The chemical luminescence intensities of the substrate decomposed by the peroxidase were detected with a sensitive CCD camera. In addition, the device was covered with a polydimethylsiloxane (PDMS) sheet containing microchannels and automated measurement was carried out. This technology is not yet commercialized, but has huge potential to be an easy-to-use tool for autoimmune detection at PoC.
Early cancer detection provides better outcomes for cancer treatment.
Microfluidics platforms are currently being used to detect genetic mutations that correspond to breast cancer, including DNA and miRNA mutations. Due to their high throughput and low time requirements, these platforms are able to analyze more sample volume in a shorter amount of time than traditional detection methods. Microfluidics chips that analyze multiple proteins in blood have been developed to save even more time and resources.
Quantum dots (QD) are a crystal material used to enhance resolution in sample images. A research scientist reported they have developed a microfluidics chip that can sample a large range of proteins within 10 minutes after sample collection. Such a chip can be combined with nanoparticles such as QD for even greater resolution with short testing time requirements. Another study utilized microfluidics chips and QDs to measure cancer biomarkers and to detect miRNAs involved with prostate as well as breast cancer.
A different microfluidic chip was used to separate blood from plasma and conduct tests within a single chip using magnetic beads and other nanoparticles.
4. Cardiovascular Diseases (CVD)
CVD are a leading cause of death worldwide. Timely and accurate diagnosis of this disease is of high interest to research, clinician, and healthcare communities. Most conventional methods for CVD biomarker detection use microwell plate-based immunoassay and polymerase chain reaction. The method is expensive, requires more time to get results, and involves complicated laboratory procedures.
Recently, LoC-based platforms for CVD biomarker sensing and analysis using various molecular and cell-based diagnostic biomarkers have been developed. These microfluidic platforms not only enable better sample preparation, chemical manipulation and reaction, and high-throughput and portability, they also provide attractive features such as label-free detection and improved sensitivity due to the integration of various novel detection techniques.
5. Sexually Transmitted Diseases (STDs)
STDs will result in a large morbidity and mortality—including birth defects and stillborn babies—if left undiagnosed and untreated. With increasing demand for a portable STD test, several companies are attempting to create a microfluidic device that can be used at home or in a doctor’s clinic.
A portable and low-cost microfluidics device for diagnosing multiple STDs (such as HIV and syphilis) is the desire of many start-ups in the diagnostic space due to the large number of patients and very attractive reimbursement rate. Several microfluidic chips have been developed and tested at the research level. Some of them incorporate a single-use plastic microfluidic cassette, a passive method for delivering reagents, and an amplification chemistry using microbeads or nanoparticles. The assay is a type of immunoassay on a protein marker. To date, the companies have demonstrated a platform ability to simultaneously detect antibodies against HIV and syphilis with small sample volumes.
In addition to my top five high impact applications for microfluidic diagnostic devices, there are many other very important microfluidic applications out there. Hundreds of research projects and clinical tests are currently being done. Once tests for autoimmune, cancer, cardiovascular, and sexually transmitted diseases are developed and proven to be safe and effective, diagnostics for such diseases will become cost-effective and readily available to patients not only in North America but also in resource-limited countries worldwide.
Lorenzo Gutierrez has over 30 years of product development experience in semiconductor, consumer electronics, and medical devices. He started working with microfluidics at the University of Tokyo in Japan in 1999, and continued developing microfluidic systems at University of Toronto in 2011. Lorenzo has developed new fabrication techniques, materials, processes, and methods in commercializing cartridges and instruments. His microfluidic applications include cell-based, immuno and molecular assays. Lorenzo specializes in overall system design, hardware engineering, integration, and translation of assay workflow to consumable cartridges. At Starfish Medical, Lorenzo manages the microfluidic cartridge development team and serves as interim site director in Toronto.