Bead-based assays are traditionally difficult to adapt for high-sensitivity quantitative point-of-care diagnostics. Here we use lensfree optical microscopes with automated image processing to quantitatively sense specific proteins in solution via the agglutination of functionalized beads within a microfluidic chip. Simple protocols and compact and inexpensive readout devices make our approach well-suited for point-of-care diagnostics. We sense interferon gamma, a biomarker of infectious and inflammatory disease, as well as NeutrAvidin. Furthermore, we discuss computational methods for improving the identification of small particles in the lensfree images, including sparsity-promoting regularized reconstruction and vectorial Green’s function modeling based on dipole electromagnetic scattering theory.

Coupling of surface-enhanced Raman spectroscopy (SERS) with the coffee ring effect can overcome the poor reproducibility typically seen when using SERS. In this study, we developed a nitrocellulose membrane paper-based substrate for coffee ring enhanced SERS, which was highly hydrophobic and produced consistent coffee rings. After optimization of solution parameters including gold nanoparticle concentration and solvent, this platform demonstrated high enhancement and low variability using Malachite Green Isothiocyanate and Moraxella catarrhalis. This substrate has the potential to increase the usability and implementation of SERS by overcoming intrinsic limitations and is more accessible than current substrates.

Antibodies that are produced following infection due to the SARS-CoV-2 virus or vaccination are critical for monitoring the immune response of an individual or the impact of the vaccine over time. As vaccines become available, there is a need for rapid, accurate, and low-cost point-of-care tools for monitoring the effectiveness of the vaccines over time at the population level. Here, we report the efficiency of a handheld point-of-care thermo-photonic device for quantifying anti-SARS-CoV-2 antibodies in humanized control positive solution. Results showed that the imager in conjunction with rapid diagnostic tests (RDT) can detect and quantify antibody levels within clinically relevant range and with a limit of detection of 0.1 µg/ml.

Lateral flow devices (LFDs) are widely used point-of-care (POC) diagnostics. The basic LFD design remains largely unchanged since their first development and this limits their use in clinical applications due to lack of sensitivity. To enhance this, we report the use of laser-patterned geometric control barriers, in the form of a constriction, that leads to a slower flow rate and smaller test zone area. This high sensitivity LFD (HS-LFD) achieved 62% increase in test line colour intensity for the detection of procalcitonin (PCT) and reduced the LOD from 10 ng/ml to 1 ng/ml with contrived human samples

Raman Spectroscopy (RS) and machine learning are explored for the rapid, real-time, sensitive application of neurological diagnostics through the human eye. Biochemical information is obtained of fatty porcine tissue and flat-mounted porcine retinal samples using an in-house built, portable RS system. RS and FUNDUS imaging have been combined with a phantom eye model to obtain spectra under eye-safe parameters in an in-vivo environment, identifying high wavenumber bands. This system has the potential to detect acute, biochemical changes indicative of neurodegenerative disorders such as Traumatic Brain Injury for early and accurate diagnoses, crucial for neurological recovery.

The structure and pigment of silicone in implantable optical sensors are critical design parameters affecting specificity, depth of light penetration, and invasiveness, volume and power consumption of the sensor. This study investigates how silicone pigment and embedded scattering agents affect sensor crosstalk and superficial tissue scattering to guide the design of silicone housings for implantable optical sensors based on their specific application. Preliminary results suggest that the magnitude of superficial tissue scattering is proportional to the principal wavelength reflected by sensor pigment. Pigment can thus be selected based on each application’s requirement for depth of penetration.