Sara Rochdi, E'26; Jean Park, E'26, Jose Rodriguez Sanchez, E'26; Jodee Frias, EG'4G, and Sergio Fantini, Ph.D. 

Frequency-domain near-infrared spectroscopy (FD-NIRS) measures cerebral hemodynamics using intensity and phase signals, but performance is often limited by motion artifacts and inconsistent optode-scalp contact. A modular FD-NIRS headset was developed with a flexible 3D-printed frame, a rod-to-hole attachment mechanism, and foam padding to improve mechanical stability, light shielding, and user comfort. Performance was evaluated using phantom testing, motion-based displacement analysis, comfort assessments with a VAS (Visual Analog Scale), and in-vivo cuff-induced oscillations. In phantom conditions, the capstone module achieved significantly higher signal-to-noise ratio with comparable phase noise relative to the DOIT system. Motion testing showed average maximum module displacement below 1 mm across trials, indicating stable module-headframe coupling. Comfort testing showed consistently lower discomfort scores for the capstone headset. In vivo results showed wavelength-dependent signal-to-noise differences but consistently reduced phase noise, indicating improved signal stability. Dual-slope measurements improved overall signal stability. These results demonstrate that improved mechanical integration enhances stability, comfort, and phase reliability, supporting more consistent FD-NIRS measurements in vivo.

Jose Armando, E'26

Advancements in prosthetic technology significantly improve mobility and independence for individuals with limb loss. Traditional prosthetic devices, while functional, often lack the adaptability and sensory feedback necessary for seamless integration into daily life. Smart materials, including shape memory alloys, piezoelectric materials, and nanostructured composites, emerge as transformative solutions in prosthetic engineering. These materials enable enhanced proprioception, real-time adaptability, and increased durability, bridging the gap between artificial limbs and biological systems.

This review examines the applications of smart materials in prosthetic interfaces, emphasizing their role in sensory enhancement, adaptive control, and biomechanical integration. Case studies, such as neural-controlled prosthetics and advanced haptic feedback systems, demonstrate the effectiveness of these innovations in restoring natural movement and tactile perception. Despite these advancements, challenges remain in manufacturing scalability, material durability, and cost accessibility. The integration of Industry 4.0 technologies, including AI-driven control systems and 3D printing, offers potential solutions to reduce costs and improve accessibility.

By examining both technological advancements and barriers to widespread adoption, this review highlights the potential of smart materials to redefine prosthetic functionality. Future research and interdisciplinary collaboration in material science, bioengineering, and neuroscience are essential in overcoming current limitations and making next-generation prosthetics more intuitive, affordable, and widely available.

Kyona Schacht, AG’25; Jose Rodriguez Sanchez, E'26; and Malika Zakarina, EG’1G

As part of a recent lab project, we explored the use of frequency-domain near-infrared spectroscopy (FD-NIRS) to characterize the optical properties of a diffuse optical phantom, simulating tissue-like scattering and absorption behavior. This work aimed to validate a multi-distance scanning configuration for accurately recovering absorption (μₐ) and reduced scattering (μ’s) coefficients across two near-infrared wavelengths (690 nm and 830 nm), relevant to biomedical optical imaging.

We implemented a linear slope method to retrieve optical properties by analyzing the amplitude (AC) and phase of diffuse reflectance measurements as a function of source-detector distance. These measurements were then linearized, and the resulting slope values were used to extract absolute optical properties. Absorption coefficients were found to be higher at 830 nm (μₐ ≈ 0.00110 mm⁻¹) compared to 690 nm (μₐ ≈ 0.00074 mm⁻¹), consistent with typical hemoglobin absorption behavior. Conversely, scattering coefficients were higher at 690 nm (μ’s ≈ 0.4914 mm⁻¹) than at 830 nm (μ’s ≈ 0.3529 mm⁻¹), reflecting expected wavelength-dependent tissue scattering trends.

All data analysis, modeling, and visualization were performed using custom MATLAB scripts, which processed raw measurement data to generate linear fits, extract optical parameters, and visualize diffuse reflectance. This workflow not only validated the FD-NIRS approach for optical property quantification but also provided hands-on experience in signal processing, light-tissue interaction modeling, and computational data analysis.

This project deepened my understanding of optical imaging physics, spectroscopy, and the practical application of computational tools for biomedical research. It demonstrates the potential of FD-NIRS as a non-invasive technique for probing tissue structure and function, with applications in medical diagnostics and tissue monitoring.

Kyona Schacht, AG’25; Jose Rodriguez Sanchez, E'26; and Malika Zakarina, EG’1G

This research laboratory paper was completed for BME-0156: Biophotonics Laboratory at Tufts University under the supervision of Maria Savvidou, Ph.D., and in collaboration with Kyona Schacht, AG’25, and Malika Zakarina, EG’1G. Our objective was to compare brightfield, phase contrast, and fluorescence microscopy in imaging biological samples, with a focus on assessing their respective advantages and limitations in contrast generation, resolution, and visualization.

We examined stained histology slides, live GFP+ and RFP+ cells, Convallaria rhizome, and 0.5 μm fluorescent beads. Brightfield microscopy provided strong contrast for stained samples but lacked effectiveness for unstained specimens. Phase contrast microscopy enhanced visualization of live, transparent cells by detecting refractive index differences, making it especially useful for imaging GFP+ and RFP+ cells. Fluorescence microscopy enabled specific imaging of cellular structures using targeted fluorophores, including DAPI for nuclei, GFP for protein fluorescence, and TRITC as a vascular or cell wall marker. However, interpreting composite fluorescence images required caution; overlapping signals sometimes obscured features, such as green fluorescence masking red emission in Figure 7f.

We also observed unexpected variations in bead size measurements at 40x magnification, likely due to focus-related limitations. Overall, our findings emphasize the trade-offs of each technique: brightfield excels with stained specimens, phase contrast enhances unstained cell visibility but can introduce halo artifacts, and fluorescence microscopy offers molecular specificity while requiring careful staining and attention to photobleaching and signal overlap. This project reinforced the importance of selecting the appropriate microscopy method based on the biological sample and research objective.

Anand Patil, A'26; Itamar Oelsner, A'25; Jose Armando, E'26; and Max Morningstar, A'23

Tufts University is spending a great deal of time and money on major infrastructure projects around campus, notably the upperclassmen dorm next to Hill Hall, an expanded & renovated gym, renovation of Eaton Hall, updates to Hodgdon Food-On-The-Run, Kindlevan, and more. However, the university has neglected to update one of the most important pieces of infrastructure for students’ day-to-day activities: pedestrian infrastructure; the vital piece of infrastructure that allows every student to get to and from their classes. Currently, there are countless accessibility issues with our pedestrian infrastructure, namely missing curb cuts and tactile strips, which make it extremely challenging for those with visibility and mobility impairments to traverse campus. In addition, there are glaringly unsafe crosswalk and intersection designs such as the crosswalk in the Medford portion of College Avenue outside the Science & Engineering Complex. Dangerous by design, crosswalks like these should never exist on a college campus with so much pedestrian traffic. Lastly, there is a general lack of attention to the quality and look of our sidewalks & pedestrian pathways, specifically on The Green/Academic Quad. This lack of attention to the aesthetics of our walking environment has been shown in studies to negatively affect mental health and reinforce car-centric design. Many other institutions of our caliber have beautiful and consistently maintained pathways throughout their entire campuses, and it is a stark contrast to what we have here at Tufts. This resolution hopes to bring to Administration's attention the numerous flaws in the pedestrian infrastructure so that they can begin to work on easy fixes immediately, and plan for a time in the future where major projects can be undertaken to ameliorate higher-level issues with our current infrastructure at Tufts.