Browsing by Author "Pott, Peter Paul"

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Open Access
Additively manufactured porous filling pneumatic network actuator
(2023) Giacoppo, Giuliano A.; Hötzel, Julia; Pott, Peter Paul
This research project investigated the additive manufacturing of pneumatic actuators based on the principle of droplet dosing using an Arburg Freeformer 300-3X 3D printer. The developed structure consists of a porous inner filling and a dense, airtight chamber. By selectively varying the filling densities of the porous inner filling, different membrane deflections of the actuator were achieved. By linking the actuators, a pneumatic network actuator was developed that could be used in endorobotics. To describe the membrane deflection of an additively manufactured pneumatic actuator, a mathematical model was developed that takes into account the influence of additive manufacturing and porous filling. Using a dedicated test rig, the predicted behavior of the pneumatic actuators was shown to be qualitatively consistent. In addition, a pneumatic network actuator (PneuNet) with a diameter of 17 mm and a height of 76 mm, consisting of nine chambers with different filling densities, could be bent through 82° under a pressure of 8 bar. Our study shows that the variation of filling densities during production leads to different membrane deflections. The mathematical model developed provides satisfactory predictions, although the influence of additive manufacturing needs to be determined experimentally. Post-processing is still a necessary step to realize the full bending potential of these actuators, although challenges regarding air-tightness remain. Future research approaches include studying the deflection behavior of the chambers in multiple directions, investigating alternative materials, and optimizing the printing process to improve mechanical properties and reliability.
Open Access
Design and evaluation of new user control devices for improved ergonomics in flexible robotic endoscopy
(2025) Heisterberg, Leander; Manfredi, Luigi; Wichmann, Dörte; Maier, Thomas; Pott, Peter Paul
Background: The ergonomics of flexible endoscopes require improvement as the current design carries a high risk of musculoskeletal injury for endoscopists. Robotic systems offer a solution by separating the endoscope from the control handle, allowing a focus on ergonomics and usability. Despite the increasing interest in this field, little attention has been paid towards developing ergonomic human input devices. This study addresses two key questions: How can handheld control devices for flexible robotic endoscopy be designed to prioritize ergonomics and usability? And, how effective are these new devices in a simulated clinical environment?
Methods: Addressing this gap, the study proposes two handheld input device models for controlling a flexible endoscope in four degrees of freedom (DOFs) and an endoscopic instrument in three DOFs. A two-stage evaluation was conducted with six endoscopists evaluating the physical ergonomics and a final clinical user evaluation with seven endoscopists using a virtual colonoscopy simulator with proportional velocity and position mapping.
Results and discussion: Both models demonstrated clinical suitability, with the first model scoring 4.8 and the second model scoring 5.2 out of 6 in the final evaluation. In sum, the study presents two designs of ergonomic control devices for robotic colonoscopy, which have the potential to reduce endoscopy-related injuries. Furthermore, the proposed colonoscopy simulator is useful to evaluate the benefits of different mapping modes. This could help to optimize the design and control mechanism of future control devices.
Open Access
Evaluation of the potential of FDM, MJF, and SLS printing technologies to manufacture reproducible and high-cycle fatigue resistant polymer springs
(2025) Derad, Lukas; Harmeling, Jens; Pott, Peter Paul
Elastic structures from polymer are a promising alternative to conventional metal springs under challenging conditions like in magnet resonance imaging (MRI) environments, where ferromagnetic materials cannot be used. The suitability of additive manufacturing to manufacture polymeric springs was assessed within the paper with a dedicated focus on stiffness reproducibility and fatigue behavior. Multi-Jet Fusion (MJF), Selective Laser Sintering (SLS), and Fused Deposition Modeling (FDM) were evaluated as manufacturing technologies. Three spring designs were conceived based on a heuristic approach, taking into account the constraint of anisotropic material behavior. MJF and SLS were used to print all three designs, respectively. Use of FDM was limited to print one design, the others were not appropriate for FDM due to high complexity. The anisotropy in mechanical characteristics of SLS and MJF printing technologies was assessed to estimate its possible influence on spring stiffness. MJF-printed tensile specimens show more anisotropic material behavior compared to SLS-printed ones. Overall suitability of FDM to print springs was shown to be limited due to design constraints and manufacturing limitations like warping and in-plane delaminations between deposited polymer strands, as well as very limited applicable cycles during fatigue testing. MJF-printed springs showed higher variability in geometric dimensions compared to SLS. Slight variances in geometric dimensions were shown to crucially influence spring stiffness, thus lowering the reliability of the MJF technology for reproducible springs. Fatigue life of either SLS or MJF samples was shown to be appropriate as all springs survived 100,000 load cycles with moderate loss of reaction force below 16% for MJF- and below 10% for SLS-printed springs. SLS was shown to be the most promising of the three evaluated printing technologies for small-scale series manufacturing of springs considering reproducibility as well as fatigue behavior.
Open Access
Feasibility of pressurized intra peritoneal aerosol chemotherapy using an ultrasound aerosol generator (usPIPAC)
(2022) Höltzcke, Phil; Sautkin, Iaroslav; Clere, Samuel; Castagna, Arianna; Königsrainer, Alfred; Pott, Peter Paul; Reymond, Marc A.
Background: We tested the feasibility of ultrasound technology for generating pressurized intraperitoneal aerosol chemotherapy (usPIPAC) and compared its performance vs. comparator (PIPAC). Material and methods: A piezoelectric ultrasound aerosolizer (NextGen, Sinaptec) was compared with the available technology (Capnopen, Capnomed). Granulometry was measured for water, Glc 5%, and silicone oil using laser diffraction spectrometry. Two- and three-dimensional (2D and 3D) spraying patterns were determined with methylene blue. Tissue penetration of doxorubicin (DOX) was measured by fluorescence microscopy in the enhanced inverted Bovine Urinary Bladder model (eIBUB). Tissue DOX concentration was measured by high-performance liquid chromatography (HPLC). Results: The droplets median aerodynamic diameter was (usPIPAC vs. PIPAC): H20: 40.4 (CI 10-90%: 19.0-102.3) vs. 34.8 (22.8-52.7) µm; Glc 5%: 52.8 (22.2-132.1) vs. 39.0 (23.7-65.2) µm; Silicone oil: 178.7 (55.7-501.8) vs. 43.0 (20.2-78.5) µm. 2D and 3D blue ink distribution pattern of usPIPAC was largely equivalent with PIPAC, as was DOX tissue concentration (usPIPAC: 0.65 (CI 5-95%: 0.44-0.86) vs. PIPAC: 0.88 (0.59-1.17) ng/ml, p = 0.29). DOX tissue penetration with usPIPAC was inferior to PIPAC: usPIPAC: 60.1 (CI 5.95%: 58.8-61.5) µm vs. PIPAC: 1172 (1157-1198) µm, p < 0.001). The homogeneity of spatial distribution (top, middle and bottom of the eIBUB) was comparable between modalities. Discussion: usPIPAC is feasible, but its performance as a drug delivery system remains currently inferior to PIPAC, in particular for lipophilic solutions.
Open Access
Investigation and validation of new heart rate measurement sites for wearable technologies
(2025) Matouq, Jumana; AlSaaideh, Ibrahim; Hatahet, Oula; Pott, Peter Paul
A recent focus has been on developing wearable health solutions that allow users to seamlessly track their health metrics during their daily activities, providing convenient and continuous access to vital physiological data. This work investigates a heart rate (HR) monitoring system and compares the HR measurement from two potential sites for foot wearable technologies. The proposed system used a commercially available photoplethysmography sensor (PPG), microcontroller, Bluetooth module, and mobile phone application. HR measurements were obtained from two anatomical sites, i.e., the dorsalis pedis artery (DPA) and the posterior tibial artery (PTA), and compared to readings from the Apple Smartwatch during standing and walking tasks. The system was validated on twenty healthy volunteers, employing ANOVA and Bland-Altman analysis to assess the accuracy and consistency of the HR measurements. During the standing test, the Bland-Altman analysis showed a mean difference of 0.08 bpm for the DPA compared to a smaller mean difference of 0.069 bpm for the PTA. On the other hand, the walking test showed a mean difference of 0.255 bpm and -0.06 bpm for the DPA and PTA, respectively. These results showed a high level of agreement between the HR measurements collected at the foot with the smartwatch measurements, with superiority for the HR measurements collected at the PTA.
Open Access
Miniature low-cost γ-radiation sensor for localization of radioactively marked lymph nodes
(2022) Behling, Merlin; Wezel, Felix; Pott, Peter Paul
Detection of metastasis spread at an early stage of disease in lymph nodes can be achieved by imaging techniques, such as PET and fluoride-marked tumor cells. Intraoperative detection of small metastasis can be problematic especially in minimally invasive surgical settings. A γ-radiation sensor can be inserted in the situs to facilitate intraoperative localization of the lymph nodes. In the minimally invasive setting, the sensor must fit through the trocar and for robot-aided interventions, a small, capsule-like device is favorable. Size reduction could be achieved by using only a few simple electronic parts packed in a single-use sensor-head also leading to a low-cost device. This paper first describes the selection of an appropriate low-cost diode, which is placed in a sensor head (Ø 12 mm) and characterized in a validation experiment. Finally, the sensor and its performance during a detection experiment with nine subjects is evaluated. The subjects had to locate a 137Cs source (138 kBq activity, 612 keV) below a wooden plate seven times. Time to accomplish this task and error rate were recorded and evaluated. The time needed by the subjects to complete each run was 95 ± 68.1 s for the first trial down to 40 ± 23.9 s for the last. All subjects managed to locate the 137Cs source precisely. Further reduction in size and a sterilizable housing are prerequisites for in vitro tests on explanted human lymph nodes and finally in vivo testing.
Open Access
Needle-based electrical impedance imaging technology for needle navigation
(2023) Liu, Jan; Atmaca, Ömer; Pott, Peter Paul
Needle insertion is a common procedure in modern healthcare practices, such as blood sampling, tissue biopsy, and cancer treatment. Various guidance systems have been developed to reduce the risk of incorrect needle positioning. While ultrasound imaging is considered the gold standard, it has limitations such as a lack of spatial resolution and subjective interpretation of 2D images. As an alternative to conventional imaging techniques, we have developed a needle-based electrical impedance imaging system. The system involves the classification of different tissue types using impedance measurements taken with a modified needle and the visualization in a MATLAB Graphical User Interface (GUI) based on the spatial sensitivity distribution of the needle. The needle was equipped with 12 stainless steel wire electrodes, and the sensitive volumes were determined using Finite Element Method (FEM) simulation. A k-Nearest Neighbors (k-NN) algorithm was used to classify different types of tissue phantoms with an average success rate of 70.56% for individual tissue phantoms. The results showed that the classification of the fat tissue phantom was the most successful (60 out of 60 attempts correct), while the success rate decreased for layered tissue structures. The measurement can be controlled in the GUI, and the identified tissues around the needle are displayed in 3D. The average latency between measurement and visualization was 112.1 ms. This work demonstrates the feasibility of using needle-based electrical impedance imaging as an alternative to conventional imaging techniques. Further improvements to the hardware and the algorithm as well as usability testing are required to evaluate the effectiveness of the needle navigation system.
Open Access
Numerical analysis of the localization of pulmonary nodules during thoracoscopic surgery by ultra-wideband radio technology
(2021) Battistel, Alberto; Pott, Peter Paul; Möller, Knut
Worldwide, lung cancer is one of the most common causes of cancer-related death. Detected by computer tomography, it is usually removed through thoracoscopic surgery. During the surgery the lung collapses requiring some strategies to track or localize the new position of the lesion. This is particularly challenging in the case of minimally invasive surgeries when mechanical palpation is not possible. Here we undertake a preliminary study with numerical analysis of an ultra-wideband (UWB) radio technology which can be employed directly during thoracoscopic surgery to localize deep solitary pulmonary nodules. This study was conducted through Finite Difference Time Domain (FDTD) simulations, where a spherical target mimicking a nodule located between 1 and 6 cm of depth and an UWB pulse at several frequencies between 0.5 and 5 GHz was used for localization. This investigation quantifies the influence of several parameters, such frequency, lesion depth, and number of acquisitions, on the final confocal image used to locate a cancer in the lung tissue. We also provide extensive discussion on several artifacts that appear in the images. The results show that the cancer localization was possible at operational frequencies below 1 GHz and for deep nodules (>5 cm), while at lower depths and higher frequencies several artifacts hindered its detection.