Opportunity
The detection and quantification of target chemical or biological species, such as biomarkers for disease diagnosis, environmental contaminants, or pathogens, is critical for healthcare, environmental monitoring, and public safety. Existing methods often rely on dedicated, bulky laboratory equipment like spectrometers, fluorescence microscopes, or thermal cyclers, which require electrical power and skilled operation, making them unsuitable for resource-limited or point-of-care settings. While portable sensors, such as lateral flow strips or colorimetric assays, offer convenience, they typically provide only qualitative results (presence/absence). Quantitative analysis still necessitates additional instruments like UV-Vis spectrometers or strip readers, involving complex processes and limiting accessibility. There is a clear need for a simple, portable, and power-free device that enables both visual and quantitative measurement of target species directly on-site without sophisticated equipment.
Technology
This patent discloses a microfluidic device designed for the visual determination and quantification of species, such as microparticles or nanoparticles, in a sample solution. The core innovation is a trap featuring a fluid channel that captures the target species, making them visible for direct observation. The device typically includes an inlet for sample introduction, the trap with a transparent or translucent channel, and a capillary pump that drives solution flow via wicking action without external power. The trap operates by physically blocking the species, either through a tapered or narrowed portion of the channel (e.g., a nozzle smaller than the particle diameter) or via a porous-material-based capillary pump (e.g., filter paper) with pores smaller than the particles, which also acts as a flow driver. Optionally, the device may incorporate processing elements like magnetic separators, mixers, or reactors upstream of the trap to pre-process the sample (e.g., separating bound from unbound particles). As species accumulate in the trap, they form a visible "bar" whose length correlates with the concentration of the target analyte. Indicators or reference markings along the channel allow for direct visual quantification, akin to reading a fuel gauge. This integration of trapping, capillary-driven flow, and visual readout enables quantitative analysis through simple, equipment-free observation.
Advantages
- Enables quantitative visual readout without external instruments like spectrometers, reducing cost and complexity.
- Portable, handheld, and power-free operation suitable for resource-limited or point-of-care settings.
- Simple fabrication using methods like 3D printing or injection molding, allowing for low-cost mass production.
- Customizable for diverse targets (e.g., nucleic acids, proteins, ions) through functionalization of particles like magnetic microparticles (MMPs) and polymer microparticles (PMPs).
- High sensitivity and selectivity, with demonstrated applications in detecting oligonucleotides, lead ions, and antibodies, even in complex bio-fluids like serum.
- Rapid results with minimal user steps, enhancing usability for self-testing or field applications.
- Integratable with pre-processing steps (e.g., magnetic separation) within a single device for automated sample handling.
Applications
- Medical diagnostics: Detection of disease biomarkers (e.g., microRNAs for cancer, proteins for malaria) and antibodies (e.g., COVID-19 mucosal antibodies for immunity monitoring).
- Environmental monitoring: Quantification of contaminants like lead ions in drinking water or toxins such as botulinum neurotoxin in food or water supplies.
- Research and quality control: Particle counting in drug delivery systems, cosmetics, or biomedical engineering for dosage verification.
- Pandemic management: Self-test kits for infectious diseases, enabling rapid, quantitative assessment of immune response or pathogen presence.
- Food safety and agriculture: Screening for pathogens or chemical residues in samples.
