The COVID-19 pandemic revealed major gaps in the design, manufacturing, planning, and procurement of medical countermeasures (MCMs). Of ongoing concern is the existing shortage of Food and Drug Administration (FDA)-regulated device MCMs needed for children disaster medical response involving acute and chronic illness. Planning for and prioritizing manufacturing, stockpiling, and tracking pediatric MCMs availability are especially necessary given existing device deficits and differences in pediatric physiology and epidemiology. In this paper, we justify why a pediatric-specific lens is needed when planning and prioritizing medical device MCMs. We also analyze the current landscape of pediatric MCM devices across phases and levels of care in relation to adult products to include protective equipment, diagnostic platforms, monitoring tools, interventional devices, and life-sustaining technologies.
Accurate assessment of arterial blood pressure (BP) and vascular stiffness is critical for diagnosing and monitoring cardiovascular disease. Arterial tonometry (AT) enables direct pulse wave acquisition and has been widely explored for noninvasive, continuous, wearable BP estimation. However, tonometry-based approaches typically rely on generalized arterial biomechanical parameters that exhibit substantial intersubject variability and can limit accuracy, particularly in pathological conditions. To address this limitation, we present a hybrid sensing framework that integrates shear wave elastography (SWE) with arterial tonometry to enable patient-specific biomechanical parameterization. The proposed device simultaneously acquires arterial stiffness metrics and pulse pressure waveforms, which are incorporated into a validated physics-driven model for continuous BP estimation. By combining elastography-derived mechanical priors with direct pulse wave measurements, this approach improves personalization and physiological fidelity of noninvasive, continuous BP monitoring. The proposed hybrid system demonstrates the potential for more accurate, patient-specific, and continuous blood pressure assessment, with implications for wearable cardiovascular monitoring and precision diagnostics.
Ventricular catheter (VC) obstruction remains one of the most common causes of cerebrospinal fluid (CSF) shunt failure in hydrocephalus patients. Material properties of VCs are hypothesized to contribute to failure, yet few studies have systematically compared alternative biomaterials using a consistent VC design and manufacturing process. This study aimed to evaluate the feasibility of producing VCs from a range of commercially available elastomeric biomaterials using a rapid prototyping process and subjecting VCs to testing aimed at validating mechanical and surface properties relative to a commercial VC. A lost-wax casting technique was employed to fabricate VCs from five biomaterials: three silicones of select hardness ratings, polyisoprene, and polyurethane. Biomaterial performance was assessed via standardized tests, including tear strength, raw material hardness, contact angle, fluid resistance, protein adsorption, and surface morphology. A benchtop system improved with oscillatory flow was used to assess protein adsorption. All fabricated VCs had similar dimensions to the commercial VC. Polyisoprene demonstrated the highest tear strength, while polyurethane exhibited the smoothest surface. Despite assessing VCs with different hardnesses, surface textures, and surface energy, there was no significant difference in protein adsorption. This work represents an effort that combines rapid lab-based manufacturing, VC material testing, and VC biological testing under clinically relevant flow direction and volume. In this way, this work offers new insight into new VC materials, a shift in prototype and testing protocols for VCs used in hydrocephalus, and suggests the need for environmental control and exposure in future testing to improve shunt longevity.
Central venous catheterization (CVC) is a common medical procedure with a complication rate of over 15%. Current CVC manikin-based simulators lack anatomical variation and objective feedback of user interaction skills, which greatly hinders effective skill acquisition. To address these limitations, a novel CVC insertion training system was developed and integrated with the Advanced Dynamic Haptic Robotic Trainer (DHRT+). This insertion training system contains a sensorized syringe, custom tissue phantom, and a tool detection subsystem, allowing residents to practice nearly the entire CVC procedure with realistic haptics and automated feedback on subcutaneous tool positioning. Five experiments were conducted to assess the haptic fidelity of the sensorized syringe and custom tissue and to evaluate the accuracy of subcutaneous tool detection. Results showed that the sensorized syringe, which detects aspiration and simulates arterial and venous flash, accurately reproduced clinical aspiration forces. The custom tissue phantom provided realistic force feedback during ultrasound (US) compression and needle insertion, comparable to that of commercial tissue phantoms at a substantially lower cost. The color sensors used to distinguish between inserted guidewires and catheters accurately verified tool depth and enabled tool insertion across multiple positions on the tissue surface. Overall, novel CVC insertion training system components were presented that enabled CVC simulation and provided accurate measurement on aspiration, guidewire depth, and catheter depth.
Microlaryngoscopic surgery requires surgeons to maintain elevated arm postures for extended periods, leading to muscle fatigue, tremors, and reduced precision. Although upper-limb exoskeletons have been widely studied for rehabilitation and assistance, their use in surgical scenarios requiring both transparent motion following and stable postural support remains limited. To address these issues, we present a tendon-sheath-driven upper-limb exoskeleton (TULE) that provides ergonomic support during prolonged procedures. The system offers three degrees-of-freedom per arm and uses a simplified dynamic model tailored to the motion patterns of microlaryngoscopic surgery. A hybrid control strategy combines admittance control with computed-torque sliding-mode control. Simulations and hardware experiments show that the proposed controller reduces joint tracking errors compared to proportional-integral-derivative (PID) control while ensuring smooth torque output. Motion-following experiments demonstrate compliant human-robot interaction with low interaction torques. Tremor-suppression tests reveal an approximately 75-80% reduction in wrist tremor amplitude in lock mode, confirming the system's potential to enhance surgeon endurance and stability in microsurgery.
Force and moment measurements are critical for powered ankle-foot prostheses, with over 73% of prototypes incorporating such sensors. Hardware complexity, compatibility limitations, and cost barriers currently limit widespread clinical adoption. This work presents four contributions using the commercial strain gauge based instrumented pyramid adapter Europa+: (1) hardware integration compatible with standard prosthetic components and minimal added bulk (275 g, 37.5 mm height); (2) an adaptive zero drift compensation algorithm achieving stable calibration within 2-3 steps for continuous long-term operation; (3) physics-informed linear regression models for real-time ankle force and moment estimation; and (4) experimental validation with 8 nonamputee participants using a passive prosthesis, and a preliminary single-participant evaluation with a two-degree-of-freedom (2DOF) powered ankle-foot prosthesis in variable impedance closed-loop operation. Results demonstrate exceptional axial force estimation ( RMSE=47 +/- 20 N, R2=0.97 +/- 0.03) and strong dorsi-plantar (DP) moment estimation ( RMSE=5.7 +/- 2.3 Nm, R2=0.87 +/- 0.06) across passive prosthesis participants, and these remain valid for the powered prosthesis. Inversion-eversion (IE) moment estimation achieves RMSE=0.8 +/- 0.2 Nm and R2=0.44 +/- 0.16 on passive data, but performance improves when model parameters are derived from powered prosthesis gait with larger active IE range. This approach establishes a generalizable methodology applicable to strain gauge based instrumented pyramid adapters, offering a practical alternative to custom sensors while significantly reducing barriers to clinical implementation of ankle dynamics estimation in prosthetic applications.
Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are widely used electrosurgical techniques for removing gastrointestinal polyps. However, these procedures often lead to complications such as bleeding, perforation, luminal strictures, and inflammation, primarily due to excessive thermal injury. In this study, we developed a radio frequency (RF) energy device capable of focusing energy more precisely at the cutting site. An impedance-based adaptive algorithm is implemented to dynamically adjust output power, thereby reducing thermal damage during tissue resection. In this study, the cutting resistance exerted on the electrode and the tissue temperature during cutting were measured, and histological sections were used to evaluate the extent of thermal injury caused during the cutting process. Under constant power outputs of 40 W, 50 W, and 60 W, average cutting resistance and temperature were recorded. Results indicate a negative correlation between output power and cutting resistance, as well as a positive correlation between output power and cutting temperature. Additionally, we compared performance between constant power and adaptive power modes at 50 W: the average cutting resistance and temperature were 0.110 +/- 0.009 N and 115.6 +/- 11.6 degrees C for the constant power mode, versus 0.096 +/- 0.013 N and 107.7 +/- 9.4 degrees C for the adaptive power mode. These findings demonstrate that the impedance-based adaptive algorithm effectively reduces tissue adhesion and thermal damage during cutting.
This study presents a data-driven framework for optimizing tympanostomy tube design to enhance fluid drainage efficiency and reduce drainage duration. Current commercial tubes often show inconsistent performance due to suboptimal fluid dynamics. The proposed approach integrates experimental data, neural network modeling, and computational optimization to refine key geometric and operational parameters. A total of 1080 experiments were conducted using 15 geometries, six materials (e.g., silicone, titanium), and two fluid types (water and Ciprodex). A neural network with two hidden layers (10 neurons each), trained via the Levenberg-Marquardt algorithm, predicted drainage outcomes of exiting droplet count and drainage duration with high accuracy (coefficient of determination (R-2) = 0.80, root-mean-square error (RMSE) = 0.62 for droplet count; R-2 = 0.92, RMSE = 2.19 for duration). Sensitivity analysis identified tube length, diameter, and inlet droplet count as the most influential parameters, while material and fluid type had limited impact. Simulated annealing (SA) (2800 iterations) was applied for multi-objective optimization, targeting maximal drainage and minimal time. Optimal designs featured increased length (1.27-1.4 mm), reduced diameter (<0.76 mm), and controlled inlet droplets (1 droplet). Experimental validation using three-dimensionally (3D)-printed PETG + PTFE prototypes confirmed model predictions, with drainage durations deviating by 7.5-10.5% and outlet droplet counts differing by at most one per trial. These results demonstrate the predictive accuracy and robustness of computational models, establishing a scalable methodology for integrating machine learning, global optimization, and low-cost prototyping in medical device design, supporting future in vivo studies and clinical translation.
Traumatic hemorrhage is a life-threatening and time-sensitive condition that can leave little to no permanent damage to a patient if treated appropriately. Military personnel encounter traumatic hemorrhage in their line of work and therefore require high-quality and realistic training in hemorrhage control techniques, such as wound packing and tourniquet application. However, not all personnel receive the same quality of training due to training or simulator fidelity, reliability, cost, and realism. Even within programs that use manikins for simulation, manikins may lack key features, such as simulated blood, patient feedback, and performance assessment metrics that allow for trainee improvement. With a growing market and increasing need for realistic bleeding control training, there is a gap to address in developing low-cost, realistic, and adaptable training models, delivering these models to appropriate trainees, and measuring learning curve and performance. In this work, we describe the development process of a bleeding control simulator, Bleed and Repeat, from the stages of design research through engineering analysis of simulated physiologic parameters. This manikin-style simulator consists of an upper extremity with a gunshot wound and includes a monitor display, embedded pressure sensor to evaluate applied pressure to the wound, adjustable pumps for blood flow, and sound emission from the manikin. Bleed and Repeat blends these components into a cohesive and immersive bleeding control training simulation that aims to replicate real-life hemorrhage in a classroom setting. The last stage of the design process was an engineering-based evaluation of simulated physiologic parameters, including blood flow rate and body temperature.
A comprehensive ten-year analysis of U.S. Food and Drug Administration (FDA) medical device authorizations by regulatory pathway, therapeutic specialty, and artificial intelligence/machine learning (AI/ML) status provides a descriptive baseline for understanding how authorization volumes, pathways, and review timelines have evolved over time. This study analyzed U.S. FDA medical device authorizations from January 2015 to June 2025 using public databases. Device submissions were categorized by regulatory pathway (premarket notification (510(k)), premarket approval (PMA), PMA supplement, De Novo), medical specialty, and AI/ML status. Visual summaries of authorization volumes, review times, and specialty distributions were generated. Of 57,641 authorizations during the study period, including both new devices and authorized changes to previously cleared or approved devices-55.7% were via 510(k), 43.1% via PMA supplements, while PMA (0.62%) and De Novo (0.58%) represented a small fraction. Authorization times varied, with PMA taking the longest (median similar to 337 days), followed by De Novo (median similar to 315 days), 510(k) (median similar to 128 days), and PMA supplements (median similar to 29 days). AI/ML-enabled device authorizations increased over the study period, predominantly through the 510(k) pathway, with radiology accounting for the largest share. These findings provide a high-level descriptive view of authorization patterns and may support contextual understanding of FDA regulatory pathways and timelines.
A voice prosthesis is a surgically implanted device used to restore speech in patients who have undergone laryngectomy, typically due to cancer. The existing voice prosthesis only works as a bypass valve which allows air flow from the trachea to the esophagus. Here, a novel membrane-based voice prosthesis was designed which actually helps in sound production, and modal analysis was conducted to study its natural frequency. The unique feature of this design is a slitted membrane, whose vibration helps in sound production. Initially, a stretched circular membrane was simulated and validated with analytical results. The same analysis was performed on a slitted membrane. The variation in modal frequency due to load (line pressure), membrane thickness, and slit dimensions was studied. It was observed that with an increase in load and length of the minor axis, the frequency of vibration of the membrane increases. The frequency of vibration of the membrane decreases with an increase in the length of the major axis. The membrane thickness had a unique effect on vibration frequency. At higher loads, increased thickness decreased frequency due to increased mass. At lower loads, frequency initially decreased and then increased with thickness, as membrane stiffness played a significant role in vibration. This paper provides a promising insight into the importance of the slitted membrane and its parameter in producing sound.
In percutaneous puncture surgery, achieving precise access to the target region while avoiding anatomical obstacles remains a critical challenge. However, due to the nonholonomic constraints of the needle, planning appropriate obstacle-avoiding paths remains challenging. To address these issues, this study proposes a novel path planning method for flexible needle puncture robots operating within tissue regions. The core contribution is to select random points generated by rapidly exploring random tree (RRT) as turning points for unicycle model-compliant paths, coupled with a grading sampling strategy to enhance computational real-time performance. Additionally, it optimizes the selection of turning points using the artificial potential field (APF) method. Compared with existing approaches, the proposed method exhibits superior performance in terms of computational efficiency and trajectory smoothness. To verify its effectiveness, both simulation experiments and puncture experiments were conducted, with a focus on analyzing computational time and the shape of actual paths. Among three experimental groups, the maximum terminal needle tip error is 1.41 +/- 0.32 mm (mean +/- standard deviation). The proposed algorithm can generate efficient safety paths, and it can be applied to the puncture procedures in the future.
Rehabilitation robotics offers a promising approach to enhancing recovery in patients with musculoskeletal or cerebrovascular injuries. This article presents the development and validation of a novel variable stiffness joint (VSJ) that replaces large motors to generate resistive forces, thereby facilitating controlled recovery of muscle tone. For a revolute joint mechanism, we show that a constant output force can be maintained by adjusting stiffness, as demonstrated through simulation studies. Further validation was conducted through prototype experiments with volunteer participants, confirming that spring-length control enables modulation of joint stiffness and maintains a constant force at the link's end regardless of the rotation angle or trajectory. This work highlights an effective actuation method capable of delivering personalized and responsive rehabilitation therapy.
Stereotyped rhythmic movements (commonly referred to as "fidgeting," "stereotypies," or "stims") are often used by individuals to support sensory and emotional regulation, enhance focus, and reduce stress. The therapeutic benefit of these movements is at least partially due to the rhythmic sensory experience generated by the movements. However, stereotyped movements can be inconvenient to engage in, or even harmful in certain contexts. To address this, we developed a discreet, wearable vest that passively delivers rhythmic sensory input through vibrating coin motors embedded between layers of fabric. Designed to be worn under clothing, the vest allows users to control vibration frequency and duty cycle via a Bluetooth-enabled smartphone app, enabling personalized optimization. The device is rechargeable and operates at full power for up to four hours. We quantified vibration pressure, signal frequency, duty cycle, battery life, noise level, and temperature. Results indicate that the device accurately maintains frequency and duty cycle within acceptable error margins and meets all engineering specifications except for battery life. All design elements and source code are openly available, allowing others to replicate or modify the device for their own use. Future work will be needed to evaluate the vest in real-world settings for safety, efficacy, and regulatory compliance.
In Vitro testing is widely used to evaluate the hemodynamic performance of transcatheter aortic valves (TAVs). However, many studies assess self-expanding valves using blood analogs matched in viscosity at room temperature, despite the temperature-dependent mechanical behavior of nitinol stent frames. This study investigates the independent and combined effects of temperature and viscosity on the in vitro performance assessment of a self-expanding TAV. Rheological characterization was performed to identify water-glycerin solutions with matched viscosities at room temperature and physiological temperature (37 degrees C). A patient-specific aortic model was cast in silicone. A self-expanding Medtronic Evolut R valve was deployed within the compliant model and evaluated using a pulse-duplicating left heart simulator under physiological flow and pressure conditions. The transvalvular pressure gradient and effective orifice area (EOA) were calculated. Rheometry identified two fluid conditions with comparable viscosities at room and body temperatures. Heating the blood analog to 37 degrees C resulted in significantly reduced transvalvular pressure gradient and increased EOA compared to the viscosity-matched room temperature condition (p < 0.0001). At physiological body temperature, the higher viscosity fluid (42% glycerin) yielded further improvements in valve performance relative to the lower viscosity fluid (38% glycerin), with lower pressure drop and larger EOA (p < 0.0001). These results demonstrate that temperature-dependent effects influence the hemodynamic performance of self-expanding nitinol TAVs beyond viscosity matching alone. Combined consideration of temperature and viscosity is therefore necessary to ensure physiologically relevant in vitro assessment of self-expanding TAVs.
In biomechanical research, accurately simulating the natural mechanical environment of articular cartilage is crucial for studying its biomechanical behavior. However, constrained by the altered properties of ex vivo biological cartilage, precisely simulating the creep response of cartilage under physiological loads remains a significant challenge in the field of tissue engineering. This study developed a confined creep device simulating in vivo conditions, integrating a servo-controlled uniaxial testing machine with high-resolution digital image correlation (DIC) to achieve noncontact three-dimensional deformation tracking, thereby enabling systematic evaluation of the creep recovery properties of cartilage. The closed-loop control system of this apparatus, featuring a downward-acting actuator and pressure/displacement sensing mechanism, ensures precise and stable detection under the optical imaging and mechanical testing. The liquid environment within the confines of the system mitigates errors arising from the time-dependent nature of biological samples and individual variations. The effectiveness of the device in reconstructing the internal mechanical environment in vitro was further verified by comparing the creep recovery behavior of the pig articular cartilage samples in a confined liquid environment with those in a nonconfined nonliquid environment. The confined environment simulates the in vivo conditions, enabling cartilage tissue to exhibit significantly superior creep performance (33 +/- 0.64% versus 55 +/- 0.76% strain accumulation, p < 0.05), and deformation recovery property, closely replicating natural mechanical behavior. This method provides an innovative platform for investigating the in vivo cartilage creep mechanisms and shows potential for optimizing tissue-engineered scaffolds.
This paper describes the design, development, and experimental evaluation of a novel steerable optical fiber for endoscopic laser surgery. The proposed device consists of an off-the shelf optical fiber installed into a flexible sheath (outer diameter: 1.6 mm) equipped with a custom distal steering mechanism. Thanks to its compact size, the proposed device can be easily deployed through the instrument channel of most commercially available clinical endoscopes. Among the procedures where we believe the new device could be beneficial, in this paper we focus on laser surgery of the larynx, i.e., the voice box. We report experimental findings, collected in in vitro models (additively-manufactured phantoms), demonstrating that the steerable fiber significantly expands surgical access, thus enabling physicians to address disease in locations that would normally be beyond reach.
Large acetabular defects in revision total hip arthroplasty (THA) revision surgery pose a major challenge in achieving stable fixation and restoring physiological load transfer. In such cases, patient-specific implants are currently used to ensure secure anchoring through customized fit. These implants can be additively manufactured to ensure price competitiveness with standard implants. A major disadvantage of metallic implants is the difference in compliance compared to human bone, which leads to stress shielding, one of the main reasons for revision surgeries. To address this challenge, this work analyzes different optimization approaches for the inner design of additively manufactured implants for large-volume defects. These approaches include the use of contact force constraints, regional strain energy constraints, or manufacturing constraints. A biomechanical finite element model of the hip with a Paprosky type 3A defect was created. The optimized implants were evaluated regarding the contact forces, the regional strain energy, and the von Mises stresses across different load cases. The results showed that the implant optimized concerning contact force and manufacturing constraints provided the most native regional strain energy and low contact forces. These parameters lead to improved implant durability and a more favorable outcome for the patient, suggesting it as a promising candidate for clinical application. Additionally, initial experimental tests were conducted. Tensile tests were performed to validate the material parameters of the model, while dynamic tests were used to evaluate the initial implant design.
Both the feasibility and clinical benefits of endoscopic interventions for colon lesions have been demonstrated by pioneering surgeons. Yet endoscopic approaches have not been widely deployed clinically because they are challenging to learn and perform with conventional endoscopes. Motivated by this, several robotic platforms have been created over the past few years with the goal of enhancing surgeon dexterity. To date, all such robots have used custom-made endoscopes with integrated manipulators. This typically results in robots significantly larger than conventional endoscopes, and the systems proposed would ultimately require hospitals to completely replace their conventional endoscopes with a new robotic solution, leading to undesirable cost and workflow ramifications. It has never before been possible to use conventional endoscopes directly with this type of system, because there were no robotic manipulators small, dexterous, and strong enough to pass through existing endoscope ports and enable the maneuvers needed to perform the surgery. In this paper, we show that the recent invention of steerable sheaths based on the concentric push-pull principle makes it possible to convert conventional endoscopes into multi-arm robotic platforms for colon procedures. We demonstrate our system in endoscopic submucosal dissection (ESD) in ex vivo porcine feasibility experiments. Even users with no prior experience in endoscopic submucosal dissection were able to successfully perform the procedure using our system.
There is a significant lack of medical devices designed for percutaneous fetal cardiac interventions, forcing clinicians to repurpose pediatric or adult devices for use in the fetal population, often at considerable risk to these patients. To help quantify this gap and drive innovation in this field, we conducted a systematic review (following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines) performing an electronic search across PubMed, Scopus, and the Cochrane databases to (1) evaluate the outcomes of off-label use of medical devices not specifically designed for fetal use in interventions addressing severe congenital heart disease (CHD) and (2) using the Stanford Biodesign methodology to identify the unmet needs that could inspire new device solutions for percutaneous fetal interventions. The search yielded 985 results, with 53 studies reviewed after screening using the established criteria. The study revealed significant rates of technical complications and adverse events that appear attributable to limitations of current devices used for percutaneous fetal cardiac intervention. This highlights the urgent need for minimally invasive cardiac devices designed exclusively for percutaneous fetal interventions. These devices should address complications and challenges in interventions for CHD, including issues with fetal positioning and cardiac access for valvular and septal procedures. These solutions should also target problems related to visualization, enable device miniaturization, and provide precision in distal device positioning and control, within a systems engineering framework to holistically address the needs of this underserved and vulnerable patient population.
