Purpose:Flickering light stimulation induces functional hyperemia, characterized by vasodilation, blood flow augmentation, and venous oxygen elevation. We present a new method to investigate the frequency dependence of metrics associated with functional hyperemia. Methods:A novel optical imaging system was developed to quantify retinal blood vessel diameter (D), oxygen saturation (SO2), and the inner retinal oxygen extraction fraction (OEF) before and after light flicker at different frequencies. Measurements were performed in 10 visually normal subjects (20-62 years) at flicker frequencies from 2 to 30 Hz. In addition, a measure of neural function was obtained by steady-state pattern electroretinography (ssPERG) across a similar range of frequencies. Results:Flicker stimulation greater than 2 Hz increased D, increased SO2 in veins, and decreased OEF. The maximum response for all metrics was obtained between 16 and 30 Hz, indicating that vascular and oxygenation metrics share a similar frequency response with light flicker. ssPERG amplitudes were positively correlated with flicker-induced increases in venous D and SO2. ssPERG amplitude was negatively correlated with flicker-induced decreases in OEF. Conclusions:We present a novel retinal imaging method to evaluate the frequency dependence of changes in D, SO2, and OEF to light flicker stimulation. The relationship between these metrics and ssPERG amplitudes was evaluated. Translational Relevance:The frequency-dependent response of retinal D, SO2, and OEF established in healthy individuals herein has the potential to serve as a biomarker of vascular and tissue abnormality in future studies of retinal disease.

Blood flow regulation has been shown to be compromised in common ocular diseases, such as diabetic retinopathy and glaucoma. The capacity of the retinal vessels to regulate blood flow can potentially serve as an oculomics biomarker for evaluating ocular and systemic diseases. Pulse-propagated intravascular pressure waves cause deformations of the vessel walls, thus offering a means to interrogate vascular compliance. The purpose of the current study is to report a method for measuring retinal pulse-propagated wave velocity (rPWV) based on spectral analysis of pulsatile intensity waveforms in human circumpapillary retinal vasculature. Arterial and venous rPWV values, as well as inter-subject variabilities of rPWV in non-diabetic and diabetic subjects, are reported. Preliminary results demonstrated the feasibility of this method for measuring rPWV and its potential for assessment of vascular plasticity in response to blood flow changes due to ocular and systemic diseases.

This paper provides the details of a poster that will be presented in the National Science Foundation (NSF) Grantees Poster Session at the 2021 ASEE Annual Conference & Exposition. The poster will report the status of an NSF Scholarships in Science, Technology, Engineering, and Math (S-STEM) project. The objectives of this project are 1) enhancing students' learning by providing access to extra and co-curricular experiences, 2) creating a positive student experience through mentorship, and 3) ensuring successful student placement in the STEM workforce, graduate, or professional school. The students who are supported by this project receive financial and educational assistance through various evidence-based modules integrated with their undergraduate education starting with the summer prior to matriculation. The students supported by this grant were recruited through one of the two project cohorts. The paper describes features such as demographics, high school GPA, and ACT/SAT scores of the participating students. The paper provides information about the completed and ongoing tasks of the project to date. The completed tasks include the development and evaluation of a summer bridge program and a freshman engineering success course. The ongoing tasks consist of the design and implementation of a service learning project course, and the design and implementation of an industry mentorship program. The paper also describes the modifications made to project tasks and resources to minimize the adverse impact of COVID-19 on the scholars. Moreover, the paper reports detailed assessment and evaluation data about the completed project tasks, and the academic success metrics of the scholars.

Modern engineers need to match technical competence with global and competitive awareness. For biomedical engineers (BMEs), efforts to support this require understanding healthcare needs, capacity for commercialization, and processes for innovation. To meet this goal, we are establishing an interdisciplinary pipeline for student-driven innovation. This work encompasses a comprehensive curriculum across disciplines to drive longitudinal project development and innovation. Our first aim is to enhance senior design (SD) project preparedness by both redesigning our interdisciplinary Clinical Immersion Program (CIP) to identify and validate clinical needs using the IDEO innovation framework and introducing a new course to enhance students' prototyping skills. Needs fully validated by BME and first-year medical students in our summer CIP ensures project development is aligned with the ability to commercialize a product, and enhanced student prototyping skills support realistic project development with enhanced fidelity. Together these efforts enable our second aim, which is to leverage interdisciplinary collaboration to enhance medtech device design by revising the undergraduate BME SD courses to incorporate the same medical students from the CIP. Moreover, the SD course will accept projects based on validated needs from CIP, which enables accelerated pacing and inclusion of both engineering design verification and validation. Projects from SD are then transitioned for further development to the same medical students who originally participated in CIP with their own required co-curricular capstone course. Continuing projects from CIP to SD and then to medical capstone has substantial benefit including the ability to retain technical progress and pursue further development that would not otherwise be possible by one capstone experience alone (e.g., publication, execution of limited studies, filing of intellectual property). In an initial implementation, demonstrating a project that transitioned through this interdisciplinary pipeline, a need related to the acquisition of tear film fluids was first identified in CIP and then transitioned to SD for technical development. The BME students rendered a functional prototype which the medical students further developed during their medical capstone. In a more methodical implementation of the pipeline in the summer of 2022, three of five proposals from CIP were transitioned into SD. Of these projects, two retained BME students from CIP. Each CIP project in SD was also benefited from comprehensive documentation. Ultimately, this distribution of projects will establish four comparative assessment groups in SD defined by the permutations between projects originating from CIP or traditional solicitation, and students having participated or not in CIP. We plan to evaluate the effects of these groups and participation in the prototyping class on project outcomes in SD and medical capstone with continued data collected for longer-term assessment. As demonstrated by our initial implementation, this pipeline has the potential to enable significant student-driven innovation.

The present paper reports an update on an NSF-funded S-STEM program currently in its last year at the University of Illinois Chicago. Lessons learned during the project implementation are also listed in the paper. A summary of the paper materials will be presented at the ASEE 2023 Annual Conference and Exposition as part of the NSF Grantees Poster Session. The project's objectives are 1) enhancing students' learning by providing access to extra and co-curricular experiences, 2) creating a positive student experience through mentorship, and 3) ensuring successful student placement in the STEM workforce or graduate/professional degree program. As part of this project, students are provided with financial assistance. A total of three Cohorts of students are supported by the project: Engineering students who started as freshmen, including 18 students of Cohort I and 13 students of Cohort II, and 19 students who transferred from various community colleges to Cohort III. More than 60% of the students are classified as minorities. This project has resulted in the creation of several support and intervention programs, including a Summer Bridge Program, an Engineering Success Initiative course, a Service Learning Project course, and an integrated mentoring program that matches each student with an academic mentor (a faculty) and an industry mentor. The paper will summarize the lessons learned from the support programs. Out of the 18 students recruited by this program as Cohort I, all have already graduated, and 16 have started a job. Cohort II students will graduate next semester (Spring 2023), and the majority of students in Cohort III students will graduate in Spring 2023. Two students dropped out of the university in their first year, and one dropped out of the university in the second year. More information is provided in this paper regarding student retention and performance (Grade Point Average).

The capstone course sequence in Biomedical Engineering (BME) provides an opportunity for students to work in a team environment to address an engineering design challenge problem as provided by an industry, clinical or engineering faculty project sponsor. This culminating project allows students to apply their acquired knowledge to a unique project that can result in multiple design outcomes. The course emphasis is placed on the engineering design cycle, project management and documentation, prototype iteration and verification and validation testing. Senior design outcomes suggest that teams rarely learn and apply new prototyping methods and instead solely rely on techniques that have been learned previously in the curriculum. Currently our BME curriculum provides lab-based curricular instruction in CAD modeling for 3D printing, additive manufacturing, Arduino microprocessors, and bioinstrumentation. This WIP paper discusses a pilot course designed for sophomore and junior engineering students to learn additional physical prototyping methods by serving as an introduction to machine-shop, woodworking, and soft material fabrication tools and techniques. In this lecture/lab course, students learn to work with wood using measuring tools, basic power tools and machine shop equipment. In addition, students are introduced to laser cutting, soft plastic molding, sewing, and various methods of fastening. As we continue to offer and refine this course, we plan to track participants through their capstone design sequence to evaluate if formal exposure and instruction in fabrication techniques impact the quality of senior design outcomes. We anticipate this course will be a valuable experience in an enhanced design curricular pathway for undergraduate BME students.

Impairments of blood flow and autoregulation have been implicated in diabetic retinopathy and glaucoma. Thus, identifying biomarkers of retinal vascular compliance and regulatory capacity is of potential value for understanding the pathophysiology and evaluating onset or progression of disease. Pulse wave velocity (PWV) represents the speed of the pulse-propagated pressure wave within blood vessels and has shown promise as a marker of vascular compliance. The purpose of the current study was to report a method for comprehensive assessment of retinal PWV based on spectral analysis of pulsatile intravascular intensity waveforms and determine alterations due to experimental ocular hypertension. Retinal PWV was linearly related to vessel diameter. Increased retinal PWV was associated with elevated intraocular pressure. Retinal PWV has the potential to serve as a vasoregulation biomarker for investigating vascular factors that contribute to the development of retinal diseases in animal models.

Vascular pulsation at the optic nerve head (ONH) reflects vessel properties. Reduction in the stimulated retinal vasodilatory capacity has been reported in diabetes, but its relation with vascular pulsation is unknown. Here we report a new retinal imaging system for correlative assessment of ONH vascular pulsation and stimulated retinal vasodilation. Retinal reflectance images were acquired before and during light flicker stimulation to quantify arterial and venous vasodilation (DAR, DVR) in subjects with and without diabetic retinopathy (N = 25). ONH vascular pulsation amplitude and frequency (PA, PF), were quantified by curve fitting of periodic intensity waveforms acquired in retinal vasculature (RV) and ONH tissue (ONHT) regions. The relationships between pulsation metrics, heart rate (HR), intraocular pressure (IOP), and vasodilatory responses were evaluated. Pulsation metrics were not significantly different between regions (p ≥ 0.70). In RV, inter-image variabilities of PA and PF were 10% and 6%, whereas inter-observer variabilities were 7% and 2% respectively. In both regions, PF was correlated with HR (p ≤ 0.001). PA was associated with DAR in both regions (p ≤ 0.03), but only with DVR in RV (p ≤ 0.05). Overall, ONH vascular pulsation was associated with stimulated retinal vasodilation, suggesting diabetes may have concomitant effects on retinal vasculature compliance and neurovascular coupling.

Droplet-based microfluidic devices have been used to achieve homogeneous cell encapsulation, but cells sediment in a solution, leading to heterogeneous products. In this technical note, we describe automated and programmable agitation device to maintain colloidal suspensions of cells. We demonstrate that the agitation device can be interfaced with a syringe pump for microfluidic applications. Agitation profiles of the device were predictable and corresponded to device settings. The device maintains the concentration of cells in an alginate solution over time without implicating cell viability. This device replaces manual agitation, and hence is suitable for applications that require slow perfusion for a longer period of time in a scalable manner.

The COVID-19 pandemic forced many Colleges and Universities across the globe to deliver education online. This online switch was abrupt and challenging for both students and instructors. Here we summarize the challenges faced in the United States at the University of Illinois at Chicago (UIC) College of Engineering during online teaching in Spring 2020 as a result of the COVID-19 pandemic and provide recommendations for the online delivery of classes. To understand the challenges faced, surveys were administered to UIC engineering students (N = 580) and instructors (N = 93). Two student focus groups were also convened (N = 56, N = 40). After the shift to online education, UIC students wanted to be on campus but not if that posed a risk to their or their family's health. Students also perceived lower quality of education after the shift. UIC College of Engineering instructors felt mostly prepared to transition online but were concerned about student learning assessment methods. Most instructors felt their classes went well and, if their classes were online in Fall 2020, planned to teach them with at least some amount of asynchronous delivery. Whenever possible, we recommend a blended approach to online teaching, offering the flexibility of asynchronous content with the engagement of a synchronous class. Other specific recommendations for lab classes, fostering a sense of student community, and student learning assessment are provided to address concerns and challenges as indicated by those surveyed. Given the unknown future epidemiological changes and willingness or the ability of students and instructors to return to campus, it is prudent to prepare for online learning in a COVID-19 world. We provide definitions, examples, considerations, and suggestions to assist in the online delivery of classes to guide and assist in this preparation.

Opportunities to provide clinical immersion experiences to bioengineering undergraduate students have expanded over the last several years. These programs allow students to observe the clinical environment in order to better understand workflow processes, the context in which medical equipment is used, and identify unmet needs firsthand. While each program focuses on identifying unmet needs, these experiences vary in content and implementation. Here we discuss features of clinical immersion programs, share details of our program after six years, and present data regarding post-graduation employment of our participants. Students who participated in the University of Illinois at Chicago Clinical Immersion Program are not more likely to pursue careers in industry as compared to non-participants, nor do they demonstrate an ability to find a job more quickly than non-participants. However, participants who did enter into industry self-reported that the program was impactful to both their career interests and ability to find their first employment position.

The diversification and enlargement of the pipeline into engineering is of great interest in education today. One way to address this issue is to expand national outreach-based STEM programs aimed at underrepresented minorities. In 2007, the National Society of Black Engineers (NSBE) created the Summer Engineering Experience for Kids (SEEK) program to address the underrepresentation of African American students in STEM fields. Today, this nationwide program is hosted each summer at sites throughout the U.S., providing access to engaging and educational engineering curricula emphasizing hands-on activities and design. Through SEEK, children between third and fifth grade participate in three engineering modules. Each one-week module focuses on a specific discipline or application within engineering, but the SEEK program does not currently have a bio(medical)engineering curriculum. Bioengineering has among the highest rates of female undergraduate enrollment among engineering disciplines (nearly 50%) and the inclusion of such a module may help increase female student interest. The authors propose two new SEEK curriculum modules in bioengineering. One module was developed to emphasize the skills and methodology that bioengineers employ, such as computer-aided design, circuitry, and programming, using the free TinkerCAD website. To reinforce the development of these skills in the context of bioengineering, students design and build their own thermometer for testing. The second module emphasizes the engineering design cycle, focusing on prototyping, testing and iteration by learning about anatomy and physiology, and iteratively designing a protective bicycle helmet. This paper reports on the development of these modules by bioengineering faculty at the University of Illinois at Chicago.

Glaucoma is an ocular disease resulting in irreversible vision loss. It is estimated more than 60 million people worldwide have glaucoma and its incidence is anticipated to increase to more than 111 million by 2040. Glaucoma causes damage to the optic nerve head (ONH) and is accompanied by loss of retinal ganglion cells and reduction in the visual field. Although increased intraocular pressure (IOP) is considered the major risk factor for the development of glaucoma, there is supportive evidence for a role of ocular microcirculation in glaucoma pathophysiology. It is thought that increased IOP may cause deformation within the ONH, thus blocking axonal transport and impeding blood flow, which can eventually lead to cell death. Clinically, imaging technologies have played a critical role in visualizing abnormalities in the ONH and retinal cell layers in glaucoma. The advent of novel optical imaging technologies with higher depth resolution, tissue penetration, and image acquisition rate has allowed quantitative evaluation of retinal anatomy and hemodynamics at cellular and capillary levels. Furthermore, the availability of multimodal imaging techniques for assessment of retinal metabolic function offers new insights into glaucoma pathophysiology. Finally, application of artificial intelligence approaches can improve and enable screening, early detection, and progression monitoring of glaucomatous damage. Overall, the application of novel optical imaging and computational techniques shows great promise for enhancing detection of glaucoma and its progression as well as for improving knowledge of glaucoma pathophysiology and development of effective therapeutic interventions to prevent vision loss.

This Complete Research paper will describe the implementation of an introductory course (ENGR194) for first semester engineering students. The course is meant to improve retention and academic success of engineering first-year students in the College of Engineering at the University of Illinois at Chicago. The implementation of this course is part of an ongoing National Science Foundation (NSF) Scholarships in Science, Technology, Engineering, and Math (S-STEM) project. This paper reports on the impact of combinatorial enrollment in ENGR194 and a previously described two-week Summer Bridge Program (SBP) offered only for entering S-STEM scholars before their first semester. To measure the impact of this course on student retention and academic success, various evaluation metrics are compared for three separate Comparison Groups (C-Groups) of students. The results show that the ENGR194 course had a significant positive impact on the first-year retention rate. The results also revealed that students who participated in both ENGR194 and SBP (C-Group 1) made changes to their declared majors earlier than students who had only taken ENGR 123 or neither of the courses (C-Groups 2 and 3 respectively). Furthermore, students in C-Group 1 received better grades in math and science than their peers, and students in C-Groups 1 and 2 had significantly higher GPAs than their peers in C-Group 3.

Abstract Diseases of the posterior segment of the eye are common causes of blindness and can be difficult to treat due to their location. Recently, there has been increased interest in the use of the suprachoroidal space to deliver therapeutics to the posterior segment. This space is accessible through a trans-scleral approach and blunt dissection of the adjacent scleral and choroidal tissues. However, despite recent commercial interest, there are few tools designed specifically to provide targeted delivery of therapeutics to a localised region within the suprachoroidal space. Therefore, we designed and prototyped a novel navigational catheter system for the targeted delivery of payloads within the suprachoroidal space. The system consists of a customised catheter tip designed to minimise blunt dissection stresses on neighbouring tissues, a mechanism for controlled catheter navigation, and a method for targeted delivery of large payloads. A customised in vitro model of the eye was also designed to visually demonstrate the capability of the catheter system to controllably navigate within the suprachoroidal space and deliver a targeted payload. This system can enable the delivery of large therapeutic payloads to the eye for the treatment of posterior eye diseases, thereby impacting the development and availability of vision-saving treatments.

Limited knowledge is currently available about alterations of retinal blood flow (F), oxygen delivery (DO2), oxygen metabolism (MO2), oxygen extraction fraction (OEF), or thickness after the ophthalmic blood vessels have been closed for a substantial interval and then reopened. We ligated the ophthalmic vessels for 120 minutes in one eye of 17 rats, and measured these variables within 20 minutes after release of the ligature in the 10 rats which had immediate reflow. F, DO2 and MO2 were 5.2 ± 3.1 μL/min, 428 ± 271 nL O2/min, and 234 ± 133 nL O2/min, respectively, that is, to 58%, 46% and 60% of values obtained from normal fellow eyes (P < 0.004). OEF was 0.65 ± 0.23, 148% of normal (P = 0.03). Inner and total retinal thicknesses were 195 ± 24 and 293 ± 20 μm, respectively, 117% and 114% of normal, and inversely related to MO2 (P ≤ 0.02). These results reflect how much energy is available to the retina immediately after an interval of nonperfusion for 120 minutes. Thus, they elucidate aspects of the pathophysiology of nonperfusion retinal injury and may improve therapy in patients with retinal artery or ophthalmic artery obstructions.

PURPOSE:Retinal ischemic injury depends on grade and duration of an ischemic insult. We developed a method to induce ischemic injury in rats permitting: (1) Variable grades of retinal blood flow (F) reduction, (2) controllable duration of F reduction, (3) injury without collateral neural damage, and (4) optical measurements of F and O2-related factors: O2 delivery (DO2), O2 extraction fraction (OEF), and metabolic rate of O2 (MO2).METHODS:In five anesthetized rats the left common carotid artery (CA) was ligated and the right CA was exposed. A variable clamp having a backstop and a rod mounted on a micromanipulator straddled the right CA. Advancing the rod with the micromanipulator produced graded compressions of the CA. F and O2-related factors were measured with established optical techniques.RESULTS:Four to seven grades of F for at least 10 minutes were achieved per rat. F decreased only with compressions of over 60%. DO2 changed in proportion to F, particularly at low F. As F decreased, OEF initially changed little, but then rose steeply to its maximum of 1 when F was approximately 4 μL/min. MO2 was stable with reduced F until OEF maximized, after which it decreased progressively.CONCLUSIONS:This model in rats permits acute, graded inner retinal ischemia that is reversible after prescribed durations, does not otherwise injure the eye and allows optical measurement of important physiologic factors during ischemia.TRANSLATIONAL RELEVANCE:This model will allow improved understanding of retinal ischemic injury and enable better management of this common, sight-threatening affliction.

PURPOSE. Reduction in inner retinal oxygen delivery (DO2) can cause retinal hypoxia and impair inner retinal oxygen metabolism (MO2), leading to vision loss. The purpose of the current study was to establish measurements of DO2 and MO2 in healthy subjects and test the hypothesis that DO2 and MO2 are reduced in sickle cell retinopathy (SCR) subjects. METHODS. Dual wavelength retinal oximetry and Doppler optical coherence tomography were performed in 12 healthy control and 12 SCR subjects. Images were analyzed to measure retinal arterial and venous oxygen content (O-2A and O-2V), venous diameter (DV), and total retinal blood flow (TRBF). Retinal arteriovenous oxygen content difference (O-2AV), DO2, MO2, and oxygen extraction fraction (OEF) were calculated according to the following equations: O-2AV = O-2A - O-2V; DO2 = TRBF * O-2A; MO2 = TRBF * O-2AV; OEF = MO2/DO2. RESULTS. Retinal DV and TRBF were higher in the SCR group as compared to the control group, whereas, O(2)A, O2V, and O(2)AV were lower in SCR group as compared to the control group. DO2, MO2, and OEF were not significantly different between control and SCR groups. MO2 and DO2 were linearly related, such that higher MO2 was associated with higher DO2. There was an inverse relationship between TRBF and OEF, such that lower TRBF was associated with higher OEF. CONCLUSIONS. Increased blood flow compensated for decreased oxygen content, thereby maintaining DO2, MO2, and OEF at predominately lower stages of SCR. Quantitative assessment of these parameters has the potential to advance knowledge and improve diagnostic evaluation of retinal ischemic conditions.