BIOMED PhD Thesis Defense

Title: 
Predicting Dementia from Spontaneous Speech Using Large Language Models

Speaker: 
Felix Agbavor, PhD Candidate
School of Biomedical Engineering, Science and Health Systems
Drexel University

Advisors:
Hualou Liang, PhD
Professor
School of Biomedical Engineering, Science and Health Systems
Drexel University

Andres Kriete, PhD
Associate Dean for Academic Affairs and Teaching Professor
School of Biomedical Engineering, Science and Health Systems
Drexel University

Details:
Alzheimer’s disease (AD) and related cognitive disorders are typically diagnosed using clinical assessments that can be costly, time-intensive, and difficult to scale for frequent monitoring. Speech provides a practical alternative because it is natural, non-invasive, inexpensive to collect, and closely coupled to cognition. This dissertation investigates how foundation-model representations can improve speech-based cognitive impairment prediction while addressing two major barriers to deployment: limited generalization beyond English and brittleness under single-modality reliance.

The dissertation develops and evaluates three complementary contributions. First, it establishes speech-only foundations for both diagnostic prediction and severity estimation. Using transcript-first modeling, large language model (LLM) embeddings extracted from spontaneous speech transcripts support accurate AD classification and cognitive score prediction, outperforming conventional handcrafted feature baselines. Using end-to-end voice modeling, self-supervised speech representations enable direct waveform-to-prediction modeling with strong discrimination and stable performance under external validation, while supporting calibrated probability outputs suitable for screening-style interpretation.

Second, the dissertation treats multilingual robustness as a first-class objective. Using the TAUKADIAL bilingual setting (English and Mandarin Chinese), it evaluates language-agnostic versus language-specific strategies built on multilingual speech embeddings. Results show that strong bilingual performance benefits from language-specific modeling and task-aware aggregation across multiple picture-description prompts, while cross-language transfer remains challenging under distribution shift.

Third, the dissertation extends beyond speech-only modeling to multimodal picture-description screening. It proposes an embedding-level fusion framework that integrates text, audio, and the shared image stimulus using cross-attention, and it evaluates unimodal, bimodal, and trimodal configurations under a unified protocol. The fusion results demonstrate that multimodal integration improves dementia prediction beyond unimodal baselines and clarifies how each modality contributes, with language content providing the dominant signal and audio and image providing complementary gains.

Overall, this dissertation demonstrates that foundation-model embeddings provide an effective backbone for scalable cognitive impairment screening from speech, but that trustworthy deployment requires explicit attention to multilingual generalization, robustness, and interpretability.

BIOMED PhD Thesis Defense

Title: 
Next-Gen Dragon Heart: A New Blood Pumping Solution for Pediatric Patients with Heart Failure

Speaker: 
Giselle C. Matlis, PhD Candidate
School of Biomedical Engineering, Science and Health Systems
Drexel University

Advisor:
Amy Throckmorton, PhD
Professor
School of Biomedical Engineering, Science and Health Systems
Drexel University

Details:
Pediatric heart failure is a life-threatening condition that affects thousands of children annually and is commonly associated with congenital heart defects, cardiomyopathies, and other severe cardiac diseases. Worldwide, pediatric heart failure has been reported to affect between 0.97 and 7.4 per 100,000 children and historically carries a mortality rate of 50–65%. In the United States alone, heart failure impacts an estimated 12,000–35,000 pediatric patients each year, resulting in approximately 14,000 hospital admissions. For children with end-stage heart failure, heart transplantation remains the gold standard treatment; however, limited donor organ availability and challenges with donor-recipient size matching, typically necessitate the use of mechanical circulatory support (MCS) devices, or blood pumps, as a bridge to transplantation. Pediatric-specific MCS options remain extremely limited, particularly, for infants. Currently, no total artificial heart (TAH) is approved for children younger than 11 years of age, creating a significant unmet need for pediatric-specific MCS technologies. To address this unmet clinical need, we are developing the Drexel Dragon Heart (DH), a novel double-pump, continuous-flow, magnetically levitated TAH for pediatric patients. The device uniquely integrates a centrifugal and an axial blood pump within a single compact housing to provide systemic and pulmonary circulatory support, while maintaining separate fluid domains; this is the first of its kind. This novel configuration allows for device usage as a TAH for partial or full cardiovascular support, or as a left-sided or right-sided blood pump based on patient support requirements. Leveraging prior research in the iterative development of this device (DH1-DH6), this dissertation work focused on the translational advancement of the centrifugal blood pump, which assists the systemic circulation and represents the largest component of the device.

An industry-standard, iterative development roadmap, incorporating design optimization, computational modeling, prototype manufacturing, hydraulic testing, hemolytic evaluation, and acute animal studies, was established and executed to design, model, build and test the next-generation centrifugal pump iterations, DH7 and DH8. The DH7 pump was advanced by implementing the Taguchi Design Optimization method to achieve size requirements and target performance requirements of 1–5 L/min of flow and 60–140 mmHg pressure rise. Computational and experimental evaluations demonstrated that the DH7 consistently achieved the desired hydraulic performance. Design areas of concern included fluid stress analyses that predicted elevated stress concentrations within the outlet volute cutwater region, guiding subsequent design improvements. Hemolytic testing of the magnetically levitated DH7 demonstrated a substantial reduction in blood damage compared with the previous DH6 design, with normalized index of hemolysis values ranging from 0.002–0.036 mg/dL, which was encouraging. Additional hydraulic blood studies confirmed successful tandem operation of the centrifugal and axial pumps without interference. The complete Dragon Heart magnetically levitated prototype (i.e. DH7 centrifugal pump + existing axial LEV-VAD pump) was further evaluated in three acute ovine studies, during which all subjects survived the full six-hour support duration and demonstrated strong hemodynamics and low thrombotic-hemolytic levels. The DH7 centrifugal pump maintained pressures within the target range while providing effective circulatory support in these animal experiments. Building upon these findings, the DH8 was developed to further reduce overall device size and fluid stresses. Development of the DH8 impeller was also facilitated through the Taguchi method. We optimized the outlet volute region of the pump to lower fluid stress levels, thereby mitigating the potential for blood cell trauma at the outlet of the centrifugal pump. The DH7 successfully produced pressures and flows within our target range and minimized the blood damage by 98.85% as compared to the DH6. In addition, the DH8 design resulted in a 40% size reduction relative to the DH7 and a 55% size reduction relative to the previous iteration, the DH6, all while maintaining the requires pressures and flows to sustain pediatric patients.

Collectively, this impactful research demonstrates excellent progress toward the translational development of a pediatric TAH. The research findings, device advancement, and success milestones significantly contribute to the body of literature of pediatric blood pump device development and further the long-term goal of establishing a new rotary TAH for the underserved population of children experiencing heart failure, thus addressing a compelling unmet clinical need.

This workshop will provide a brief overview of NSF GRFP application components, then walk you through reflection and planning exercises to help you map out your application process.

This is the first of four biweekly summer workshops on the NSF GRFP; applicants are also encouraged to participate in our grad fellowships biweekly writing group. You can learn more about these events and review materials from previous info sessions and workshops on our NSF Applicant Resource Site (Drexel login required).

The National Science Foundation’s Graduate Research Fellowship Program (GRFP) provides selected fellows with three years of funding, including a living stipend and tuition funds, to support a research-focused doctoral degree in STEM, social sciences, or STEM education. The current application cycle is open to US citizens and permanent residents planning to begin their first graduate program in Fall 2027, or who will be in the 1st year of a PhD program in Fall 2026. BS-MS students planning to continue on to a PhD program are only eligible to apply in their final year of BS-MS study (and not as first year doctoral students).

Register on Zoom to attend

BIOMED PhD Thesis Defense

Title: 
Development of a Geometrically Tunable Cardiovascular Shunt for Pediatric Heart Reconstruction

Speaker: 
Akari Seiner, PhD Candidate
School of Biomedical Engineering, Science and Health Systems
Drexel University

Advisor:
Christopher Rodell, PhD
Associate Professor
School of Biomedical Engineering, Science and Health Systems
Drexel University

Details:
Congenital heart defects (CHDs) are the most common class of birth anomalies, affecting approximately 1% of live births globally and representing a leading cause of infant morbidity and mortality worldwide. A critical subset, collectively termed single ventricle (SV) defects, are characterized by the functional or morphological inadequacy of one ventricle, leaving a single dominant ventricle to simultaneously support both pulmonary and systemic circulations. Among these, hypoplastic left heart syndrome (HLHS) is the most prevalent and severe, accounting for 25 – 40% of all neonatal cardiac deaths. Without surgical intervention, SV defects are universally fatal. The current standard of care is staged palliative reconstruction, the Norwood–Glenn–Fontan procedure, in which the initial Norwood procedure establishes parallel circulation via implantation of a fixed-diameter modified Blalock–Taussig–Thomas (mBTT) shunt. Despite decades of iterative refinement of surgical procedures and post-operative care, interstage mortality remains as high as 39%, with nearly 48% of patients requiring invasive shunt revision due to the device's inability to accommodate the rapid somatic growth of the developing infant. These persistent limitations motivate the development of a geometrically adaptive shunt capable of dynamically adjusting its lumen diameter without reoperation.

To address these limitations, this work develops a geometrically tunable cardiovascular shunt for pediatric heart reconstruction. Photoresponsive methacrylated dextran (DexMA) hydrogels were synthesized and integrated as luminal linings within polytetrafluoroethylene (PTFE) and expanded PTFE (ePTFE) shunt conduits. A dual-stage crosslinking strategy — combining covalent Michael addition crosslinking with a secondary blue-light photopolymerization step — was established to achieve controlled volumetric contraction of the hydrogel lining upon irradiation, thereby expanding the inner lumen diameter. Systematic investigation of polymer modification, concentration, and dithiothreitol (DTT)-to-methacrylate molar ratios yielded an optimized formulation of 50% modified DexMA at 10%w/v with a 40% DTT/methacrylate ratio. With this formulation, volume changes exceeding 39% were achieved, enabling clinically relevant increases in lumen diameter. Building on this material platform, comprehensive biological safety was established in accordance with ASTM and ISO standards. Hydrogels exhibited excellent long-term hydrolytic stability (> 3 months), cytocompatibility (including both 3T3 fibroblast and HUVEC cell lines), lack of immune response (RAW264.7 cells, primary human PBMCs), and hemocompatibility (absence of complement activation, platelet aggregation, or hemolysis) across hydrogel formulations, collectively demonstrating the platform's suitability for a blood-contacting vascular environment.

The hydrogel platform was integrated into full-scale shunt prototypes using polydopamine (PDA)-mediated surface functionalization to ensure robust hydrogel-to-PTFE interfacial bonding. Incremental exposure to catheter-delivered blue light via a fiber-optic radial diffuser produced precise lumen diameter expansion up to 40%. Programmable expansion patterns, including incremental weekly increases and one-time targeted adjustments, remained structurally stable over one month. These results were subsequently translated to clinical-grade ePTFE, where comprehensive multi-axial mechanical characterization demonstrated dimensional stability under physiological arterial pressures up to 160 mmHg, and light-activated expansion in ePTFE was statistically equivalent to that achieved in rigid PTFE prototypes.

Evaluation of the tunable shunt under simulated physiological flow conditions was performed using ASTM F1841-19 compliant dynamic hemocompatibility testing and an ex vivo perfusion platform. Dynamic hemocompatibility confirmed that the hydrogel lining does not introduce additional hemolytic shear compared to controls. Hemodynamic perfusion testing over a flow range of 300 – 1000 mL/min demonstrated a highly linear pressure-flow relationship (R² = 0.99), consistent with the physiological range of neonatal cardiac output. Non-invasive nanoCT imaging of shunts before and after flow exposure confirmed structural integrity and dimensional stability of the inner lumen, with no significant differences in lumen diameter or circularity. Together, these findings establish proof-of-concept for a light-responsive, geometrically tunable cardiovascular shunt capable of accommodating infant growth through minimally invasive catheter-based actuation, offering a promising strategy to reduce interstage mortality and reintervention burden in pediatric SV palliation.

As international students prepare to travel to and begin their graduate study in the US, the Office of Graduate Studies of Drexel University is committed to helping make the transition as smooth as possible. The Office of Graduate Studies, in partnership with the International Graduate Student Association (IGSA) and campus partners, hosts a series of optional but highly encouraged pre-arrival webinars over the summer to help incoming international graduate students prepare for graduate study in the US, arrival to and life in the US and Philadelphia, and to answer any questions about student life and graduate study at Drexel.

The webinars include:

-A welcome and introduction by members of the Office of Graduate Studies, International Students and Scholars Services (ISSS), Counseling and Health Services, the Steinbright Career Development Center (SCDC), Drexel Central, and members of the International Graduate Student Association (IGSA);
-A comprehensive overview of life in the US, in Philadelphia, and at Drexel, advice on what to bring and how to prepare for your arrival in the US, and how to prepare for graduate and academic study at Drexel;
-A Question & Answer (Q&A) session featuring current international graduate students, professional staff members to answer questions about immigration requirements, health insurance, immunizations, billing, co-op and career services, and a wide range of other topics!

Join the Zoom

This workshop will provide a deep dive into the NSF GRFP Research Statement. It is helpful for attendees to have a research direction in mind, but applicants at all stages will benefit from attending.

This is the second of four biweekly summer workshops on the NSF GRFP; applicants are also encouraged to participate in our grad fellowships biweekly writing group. You can learn more about these events and review materials from previous info sessions and workshops on our NSF Applicant Resource Site (Drexel login required).

The National Science Foundation’s Graduate Research Fellowship Program (GRFP) provides selected fellows with three years of funding, including a living stipend and tuition funds, to support a research-focused doctoral degree in STEM, social sciences, or STEM education. The current application cycle is open to US citizens and permanent residents planning to begin their first graduate program in Fall 2027, or who will be in the 1st year of a PhD program in Fall 2026. BS-MS students planning to continue on to a PhD program are only eligible to apply in their final year of BS-MS study (and not as first year doctoral students).

Register on Zoom to attend

As international students prepare to travel to and begin their graduate study in the US, the Office of Graduate Studies of Drexel University is committed to helping make the transition as smooth as possible. The Office of Graduate Studies, in partnership with the International Graduate Student Association (IGSA) and campus partners, hosts a series of optional but highly encouraged pre-arrival webinars over the summer to help incoming international graduate students prepare for graduate study in the US, arrival to and life in the US and Philadelphia, and to answer any questions about student life and graduate study at Drexel.

The webinars include:

-A welcome and introduction by members of the Office of Graduate Studies, International Students and Scholars Services (ISSS), Counseling and Health Services, the Steinbright Career Development Center (SCDC), Drexel Central, and members of the International Graduate Student Association (IGSA);
-A comprehensive overview of life in the US, in Philadelphia, and at Drexel, advice on what to bring and how to prepare for your arrival in the US, and how to prepare for graduate and academic study at Drexel;
-A Question & Answer (Q&A) session featuring current international graduate students, professional staff members to answer questions about immigration requirements, health insurance, immunizations, billing, co-op and career services, and a wide range of other topics!

Join the Zoom

This conversational event led by Dr. Matt Lerner of the Autism Institute shares insight as to what exactly a Graduate Clinical Psychology Program entails and what career paths can come of it. This is an interactive event.

The Office of Graduate Studies offers series of informational and professional development workshops to help students get acquainted with campus resources and services as they prepare to begin their graduate study. These workshops are optional but highly encouraged. The workshops will be recorded and archived on this website for later viewing.

Canvas is a Learning Management System (LMS) used by Drexel to support teaching and learning in digital environments. This workshop provides an introduction to Canvas and its key features, including course navigation, accessing learning materials, submitting assignments, participating in discussions, communicating with instructors and classmates, and tracking grades and academic progress. Participants will gain practical experience using Canvas tools and learn strategies for effectively managing coursework, staying organized, and maximizing their learning experience within the platform.

Facilitated by Michael Shelmet, EdD, Director of Instructional Technology, Drexel University Information Technology

Join the Zoom