Daniel Lorias-Espinoza

Articulated endoscopic instruments can enhance dexterity within constrained workspaces; however, their complexity and cost limit accessibility for training, prototyping, and early-stage evaluation. Additive manufacturing offers a practical approach for developing mechanically functional, low-cost articulated devices for engineering exploration and simulation-oriented applications. This study describes the mechanical design, bench-top characterization, and preliminary proof-of-concept assessment of two additively manufactured, cable-driven endoscopic prototypes: a flexible endoscope with an integrated working channel and bidirectional distal articulation, and a 4-mm steerable surgical forceps with independent jaw actuation. Both devices were fabricated using fused deposition modeling. Bench-top experiments quantified distal deflection, motion repeatability, force-related behavior, simulated task execution, and user perception. The flexible endoscope achieved effective distal deflections of 178° ± 2° vertically and 171° ± 3° horizontally while maintaining compatibility with standard 2.8-mm endoscopic instruments. During cyclic testing, it demonstrated sub-centimeter positional consistency after 1000 articulation cycles, with 95th percentile errors below 8 mm in both directions. The steerable forceps exhibited a geometric articulation range of 180°, an effective distal deflection of 85° ± 2°, and repeatable tip motion over 500 cycles, with a mean positional error of 0.26 mm. Simulated tasks were completed with high user perception scores for both prototypes. Fabrication costs were USD 166.49 for the endoscope and USD 27.75 for the forceps. These findings suggest that cable-driven architectures combined with additive manufacturing can reproduce key kinematic principles of articulated endoscopic instruments using low-cost fabrication methods. The prototypes should be interpreted as early-stage engineering demonstrators rather than clinically deployable devices.

Background: The aim of this study is to present the construct validity of the ScopePro Trainer system and determine its effectiveness as a training and objective assessment tool for surgeons’ psychomotor laparoscopic skills. Methods: Four surgeons, eight PG2 to PG4 residents, and twenty medical students participated in this study. All participants performed three FLS-based tasks using conventional laparoscopic instruments and the ScopePro Trainer system. Using the linearity principle of the spiral, a passive marker was added to each instrument, shaped like a spiral. Six metrics related to time, linear motion, and angular motion were used to assess the laparoscopic performance of the participants in all tasks. Statistical analysis was performed using the analysis of variance (ANOVA) test, followed by a Student’s t test with Tukey’s correction for multiple testing. Results: The performance of ScopePro Trainer is illustrated by the graphical representation of the instruments' paths and the calculations of metrics derived from their position and rotation. Outcomes presented significant differences in the participant's skills during the execution of three surgical training tasks. Conclusions: The ScopePro Trainer system has been presented and successfully validated. Outcomes showed that ScopePro was able to differentiate between participants with varying levels of laparoscopic expertise. The ScopePro Trainer offers an alternative to traditional tracking systems for analyzing the rotational motion of surgical instruments.

The article emphasizes the critical role of flexible endoscope handling in the training of gastroenterologist surgeons, while highlighting the limitations posed by workload and restricted access to surgical simulators. To address these challenges, the Society of American Gastrointestinal and Endoscopy Surgeons (SAGES) developed the Fundamentals of Endoscopy Surgery (FES) program, which assesses essential skills through tasks such as retroflexion, surgical target identification, and loop reduction. The EndoNavSkill 01 system, currently in the conceptual phase, includes a medium-sized gastric model, a flexible endoscope, and a computerized interface that provides real-time control, visualization, and data recording. The endoscope tip has two additional degrees of freedom (DOF) and a 20 mm diameter. The tip is 150 mm long and has a working channel for 3 mm instrumentation. It has been tested with a commercial biopsy forceps. Preliminary tests demonstrated that the system achieved 180-degree retroflexion with half a turn of the control knobs, successfully visualizing the gastric cavity entry. Regarding precision, the endoscope's positional errors were recorded as 0.50% along the X-axis, 0.90% along the Y-axis, and 1.15% along the Z-axis. Additional metrics recorded included the time required to complete tasks, surgical target identification, extraction task, and the endoscope's path in coordinates 3D. EndoNavSkill 01 is a master's project currently in development and distinguishes itself by allowing the use of real instruments, unlike virtual simulators that rely on idealized conditions and are often prohibitively expensive. Although the prototype has met key design objectives such as achieving retroflexion and verifying the working channel's functionality, further testing and development are required to optimize the system and confirm its suitability for clinical environments.

Purpose.The aim of this work is to present a new physical laparoscopy simulator with an electromyography (EMG)/accelerometry-based muscle activity recording system, EvalLap EMG-ACC, and perform objective evaluation of laparoscopic skills based on the quantification of muscle activity of participants with different levels of laparoscopic experience. Methods. EMG and ACC signals were obtained from 14 participants (6 experts, 8 medical students) performing circular pattern cutting tasks using a laparoscopic box trainer with the Trigno (Delsys Inc, Natick, MA) portable wireless system of 16 wireless sensors. Sensors were placed on the proximal and distal muscles of the upper extremities. Seven evaluation metrics were proposed and compared between skilled and novice surgeons. Results. The proximal and distal arm muscles (trapezius, deltoids, biceps, and forearms) were most active while executing laparoscopic tasks. Laparoscopic experience was associated with differences in EMG amplitude ([ ]), muscle activity ([ ]), hand acceleration ([ ]), user movement ([ ]), and muscle fatigue. For the cutting task, the deltoid, bicep, forearm EMG amplitude, and user movement significantly differed between experience groups. Conclusion. This pilot study demonstrates that different muscle groups are preferentially activated during laparoscopic tasks depending on the level of surgical experience. Expert surgeons showed less muscle activity compared with novices. EvalLap EMG-ACC represents a promising means to distinguish surgeons with basic cutting skills from those who have not yet developed these skills.

Background. This article aims to present an innovative design of a steerable surgical instrument for conventional and single-site minimally invasive surgery (MIS), which improves the dexterity and maneuverability of the surgeon while offering a solution to the limitations of current tools. Methods. The steerable MIS instrument consists of a deflection structure with a curved sliding joints design that articulates the distal tip in two additional degrees of freedom (DoFs), relative to the instrument shaft, using transmission by cables. A passive ball-joint mechanism articulates the handle relative to the instrument shaft, improves wrist posture, and prevents collision of instrument handles during single-site MIS procedures. The two additional DoFs of the articulating tip are activated by a thumb-controlled device, using a joystick design mounted on the handle. This steerable MIS instrument was developed by additive manufacturing in a 3D printer using PLA polymer. Results. Prototype testing showed a maximum tip deflection of 60° in the left and right directions, with a total deflection of 120°. With the passive ball-joint fully offset, the steerable tip achieved a deflection of 90° for the right and 40° for the left direction, with a total deflection of 130°. Furthermore, the passive ball-joint mechanism in the handle obtained a maximum range of motion of 60°. Conclusions. This steerable MIS instrument concept offers an alternative to enhance the application fields of conventional and single-site MIS, increasing manual dexterity of the surgeon and the ability to reach narrow anatomies from other directions.

The physicochemical characterization of pharmaceutical materials is essential for drug discovery, development and evaluation, and for understanding and predicting their interaction with physiological systems. Amongst many measurement techniques for spectroscopic characterization of pharmaceutical materials, Electrical Impedance Spectroscopy (EIS) is powerful as it can be used to model the electrical properties of pure substances and compounds in correlation with specific chemical composition. In particular, the accurate measurement of specific properties of drugs is important for evaluating physiological interaction. The electrochemical modelling of compounds is usually carried out using spectral impedance data over a wide frequency range, to fit a predetermined model of an equivalent electrochemical cell. This paper presents experimental results by EIS analysis of four drug formulations (trimethoprim/sulfamethoxazole C₁₄H₁₈N₄O₃-C₁₀H₁₁N₃O₃, ambroxol C₁₃H₁₈Br₂N₂O.HCl, metamizole sodium C₁₃H₁₆N₃NaO₄S, and ranitidine C₁₃H₂₂N₄O₃S.HCl). A wide frequency range from 20 Hz to 30 MHz is used to evaluate system identification techniques using EIS data and to obtain process models. The results suggest that arrays of linear R-C models derived using system identification techniques in the frequency domain can be used to identify different compounds.