Theses Doctoral

Development and evaluation of point-of-care diagnostic technologies for providers and consumers

Nayak, Samiksha

Point-of-care (POC) diagnostic technologies aim to expand access to traditional laboratory-based testing to near-patient settings. These settings can range from emergency or intensive care-units (ICUs) in the United States, to remote health posts in sub Saharan Africa. Differences in budget and infrastructure play a role in characterizing the wide array of possible “near patient” settings and must be taken into consideration in the engineering design process. In this dissertation we use translational engineering to develop practical and accessible microfluidic POC immunoassays for diverse settings, that include both provider and consumer facing applications.
First, we examined Lyme Disease in the U.S., where existing diagnostic technologies face the challenge of rapid and accurate serodiagnosis in the face of largely non-specific clinical symptoms. We developed a multiplexed rapid test that could replicate enzyme-linked immunosorbent assay (ELISA) performance for Lyme Disease diagnosis. After screening candidate biomarkers, we evaluated performance of the multiplexed microfluidic test against ELISA using clinical serum samples and illustrated the potential to streamline current clinical algorithms requiring two immunoassays (ELISA and Western Blot) into one standalone test suitable for physician’s offices or urgent care clinics in the U.S. We also showed exploratory work towards a similar multiplexed test design for another bacterial spirochete infection, Leptospirosis.
Next, we built on previous work towards a POC HIV-syphilis antenatal screening tool, to develop a smartphone-integrated, microfluidic assay for healthcare workers to use in low resource settings. The low-cost ($34), re-usable device (“smartphone dongle”) costs $34 to produce and provides results in 15 minutes. In this work, we focus on assay development efforts undertaken towards development of a fully integrated POC product suitable for deployment in the field, with practical considerations for the use of fingerstick blood, stability, scale-up and transport. We also streamlined the number of manual steps for end-user operation, through the use of lyophilized secondary antibodies, preloaded reagents on cassette, and an automatic result readout. While laboratory demonstration with clinical samples is important for initial characterization of POC devices, field evaluation reveals diagnostic performance under real-world conditions. We tested the device in the hands of minimally trained healthcare workers in Rwanda and saw comparable performance to other immunoassays run under field conditions. We also performed a follow-up pilot field study in Rwanda to evaluate the feasibility of the smartphone dongle platform for self-testing by patients/consumers in a low-resource setting, one of the most challenging use-cases for POC devices.
Finally, we sought to integrate intellectual frameworks from behavioral research and user-experience (UX) design in creating a new framework for evaluation of consumer-facing microfluidic devices, specifically towards HIV home-testing in the U.S. While overall rates of HIV are decreasing in the U.S., the population of gay, bisexual and other men who have sex with men (MSM) are disproportionately affected. Self-testing products for sexually transmitted infection (STI) testing could address unmet needs for these target populations in both increasing access and frequency of testing, as well as integrating use with sexual partners for early diagnosis or even prevention. We worked with a cohort of MSMs at high risk for HIV/STI transmission in New York City, and performed for the first time, a structured assessment of completely naïve users interacting with a smartphone interfaced microfluidic diagnostic device (“SMARTtest”). We integrated UX design value model of device usability, credibility, accessibility and acceptability into our evaluation framework, which influence user’s information, knowledge, motivation and behavioral skills towards engaging with a prevention method (“IMB” model). Thus far, such frameworks have rarely been applied to other consumer health monitoring devices, including microfluidic POC devices. As the microfluidic field moves towards more field demonstrations of devices, more untrained and minimally trained users will have access to such tools. It is important to understand how they use devices, what the device failure points are and what the most relevant design features are to spur user adoption and meaningful usage.
Underlying our work in creating accessible and practical POC immunoassay tools for infectious disease detection, is the illustration of the translational development roadmap from proof-of-concept assay development to field studies and user-based evaluations for intended end-use settings that range from U.S. based primary care clinics, rural health centers in low-resource settings as well as self-testing environments in both. Incorporating an understanding of the target use-case setting is critical in translating technologies for clinical use, whether in the infrastructure and services that are available, or end-user needs and constraints such as clinical workflow patterns, level of technical expertise and perceptions of usefulness and value. We show how user/use-case focused application of downstream translational engineering and testing informs upstream design choices and accelerates development of POC devices for real-world use. The sum of this work aims to illustrate tenets of translational engineering design and testing to advance insight into building POC products that are poised for greater adoption by target end users, whether they are health providers or consumers.


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More About This Work

Academic Units
Biomedical Engineering
Thesis Advisors
Sia, Samuel K.
Ph.D., Columbia University
Published Here
May 15, 2018