UC San Diego

Medical devices enable crucial insight into fundamental biological processes, development and disease. In this dissertation we present three medical devices for cellular discovery and diagnostics. In chapter I, we demonstrate a label- free image-encoded microfluidic cell sorter with a scanning Bessel beam. Microfluidics- based cell sorters offer a convenient, high information content, disposable solution that overcomes many of the disadvantages of conventional cell sorters. However, flow confinement in the microfluidic channel is generally one-dimensional via sheath flow. Consequently, the equilibrium cell distribution spreads outside the focal plane of commonly used Gaussian laser excitation beams, giving rise to a high number of blurred images that hinder subsequent cell sorting based on cell image features. To address this issue, we present a Bessel–Gaussian beam image-guided cell sorter with an ultra-long depth of focus, enabling focused images of >85% of passing cells. This system features label-free sorting capabilities based on features extracted from the output temporal waveform of a photomultiplier tube (PMT) detector. In chapter II, we demonstrate an automated, high throughput diagnostic device suited for high-traffic settings. Here we demonstrate a multiplex reverse-transcription loop-mediated isothermal amplification (RT-LAMP) coupled with a gold nanoparticle-based lateral flow immunoassay (LFIA) capable of detecting up to three unique viral gene targets in 15 min. RT-LAMP primers associated with three separate gene targets from the SARS-CoV-2 virus (Orf1ab, Envelope, and Nucleocapsid) were added to a one-pot mix. A colorimetric change from red to yellow occurs in the presence of a positive sample. Positive samples are run through a LFIA to achieve specificity on a multiplex three-test line paper assay. Positive results are indicated by a characteristic crimson line. The device is almost fully automated and is deployable in any community setting with a power source. In chapter III, we demonstrate a novel prototype and concept for cold plasma – based live cell lithography. A plasma jet is formed using a custom dual – lead nozzle, high voltage alternating current transformer, nitrogen feed gas, and frame. The concept aims to leverage the batch processing and spatial resolution advantages of lithography to identify, preserve, and isolate cells of interest while preserving their spatial information.