Benchtop Validation Research Articles

Tethered spinal cord tension assessed via ultrasound elastography in computational and intraoperative human studies

BackgroundTension in the spinal cord is a trademark of tethered cord syndrome. Unfortunately, existing tests cannot quantify tension across the bulk of the cord, making the diagnostic evaluation of stretch ambiguous. A potential non-destructive metric for spinal cord tension is ultrasound-derived shear wave velocity (SWV). The velocity is sensitive to tissue elasticity and boundary conditions including strain. We use the term Ultrasound Tensography to describe the acoustic evaluation of tension with SWV.MethodsOur solution Tethered cord Assessment with Ultrasound Tensography (TAUT) was utilized in three sub-studies: finite element simulations, a cadaveric benchtop validation, and a neurosurgical case series. The simulation computed SWV for given tensile forces. The cadaveric model with induced tension validated the SWV-tension relationship. Lastly, SWV was measured intraoperatively in patients diagnosed with tethered cords who underwent treatment (spinal column shortening). The surgery alleviates tension by decreasing the vertebral column length.ResultsHere we observe a strong linear relationship between tension and squared SWV across the preclinical sub-studies. Higher tension induces faster shear waves in the simulation (R2 = 0.984) and cadaveric (R2 = 0.951) models. The SWV decreases in all neurosurgical procedures (p < 0.001). Moreover, TAUT has a c-statistic of 0.962 (0.92-1.00), detecting all tethered cords.ConclusionsThis study presents a physical, clinical metric of spinal cord tension. Strong agreement among computational, cadaveric, and clinical studies demonstrates the utility of ultrasound-induced SWV for quantitative intraoperative feedback. This technology is positioned to enhance tethered cord diagnosis, treatment, and postoperative monitoring as it differentiates stretched from healthy cords.

A risk and credibility framework for in silico clinical trials of medical devices

Background and objectiveThe use of in silico clinical trials (ISCTs) to generate clinically-relevant data on new medical devices is an emerging area of regulatory research. Interest in ISCTs stems from recognized challenges in acquiring sufficient clinical data and the continued maturation of in silico technologies. There is currently no guidance in place for evaluating the credibility of ISCT applications. The objective of this work was to adapt an existing risk-based credibility framework specifically for ISCT applications, and demonstrate its utility on a contemporary case study. MethodsExpanding on guidance currently in place for assessing the risk of traditional modeling applications of medical devices and demonstrating model credibility through benchtop validation activities, a framework is proposed to (1) evaluate the model risk for ISCT applications based on the independent factors of scope, coverage, and severity, and (2) assess the credibility of clinical validation activities based on consideration of the clinical comparator, the validation model, the agreement between the two, and the applicability of the clinical validation activities to the ISCT application. ResultsThe resulting framework spans across the range of ISCT applications that may be envisioned, as well as the variety of clinical datasets that can be used to demonstrate model credibility. Credibility factors reflect the expected clinical variability in the validation comparator and validation model, the statistical power of the comparator, the rigor of agreement between the comparator and model in terms of both inputs and outputs, and the overall similarity of the device in the validation activities to the device within the intended ISCT. When applied to a high-risk case study, the framework reveals that planned clinical validation activities require additional rigor in order to achieve the credibility targets, enabling an assessment of the validation effort relative to the potential benefit prior to investing in the validation studies. DiscussionAn objective and risk-based framework for establishing credibility requirements for ISCT applications is a critical step in advancing ISCT from theory to practice. The proposed framework enforces that appropriate validation of ISCT applications requires evidence that the intended clinical environment is accurately represented. The framework will contribute to reducing uncertainty amongst technical, clinical, and regulatory constituents on ISCT applications, and promote rational adoption.

MRI-Conditional Eccentric-Tube Injection Needle: Design, Fabrication, and Animal Trial.

Effective radiation therapy aims to maximize the radiation dose delivered to the tumor while minimizing damage to the surrounding healthy tissues, which can be a challenging task when the tissue-tumor space is small. To eliminate the damage to healthy tissue, it is now possible to inject biocompatible hydrogels between cancerous targets and surrounding tissues to create a spacer pocket. Conventional methods have limitations in poor target visualization and device tracking. In this paper, we leverage our MR-tracking technique to develop a novel injection needle for hydrogel spacer deployment. Herein, we present the working principle and fabrication method, followed by benchtop validation in an agar phantom, and MRI-guided validation in tissue-mimic prostate phantom and sexually mature female swine. Animal trials indicated that the spacer pockets in the rectovaginal septum can be accurately visualized on T2-weighted MRI. The experimental results showed that the vaginal-rectal spacing was successfully increased by 12 ± 2 mm anterior-posterior.

A Wearable Wideband Analog Bio-Impedance Analyzer for Real-Time Monitoring of Human Physiology.

Continuous monitoring of electrophysiological activities of the human body is a significant step toward the effective prognosis, diagnosis, and management of functional disorders and cardiovascular diseases. This paper presents the development of a wireless system for the real-time acquisition of hemodynamics data and ambulatory monitoring of body composition based on electrical bio-impedance (Bio-Z) analysis. The developed system is composed of a low-power wearable unit and a stationary unit connected to a computer. The system conducts the non-radiative non-invasive Bio-Z analysis over a wide bandwidth of 1 MHz through four independent channels. The proposed analog approach detects the physiological activity by extracting the magnitude of the mixed Bio-Z signal, in real-time. A graphical user interface was designed for monitoring, analysis, and storage of the processed data. Moreover, the amplitude and frequency of the electrical excitation signals can be instructed through the user interface, wirelessly. Bench-top validation of the system demonstrated the delivery of current signals over a wide frequency range of 1 kHz - 1 MHz and peak-to-peak amplitude of up to 20 mA. Besides, the system was able to detect the magnitude of the envelope of the mixed signal with amplitude modulation depths as low as 0.1 %. Clinical Relevance- The system provides the real-time monitoring of cardiac activity and blood pulsation in human arteries. In addition, due to the configurability of the frequency and amplitude of the current injection circuit, the system is an excellent candidate to be utilized for real-time medical imaging through electrical bio-impedance tomography as well as electrical bio-impedance spectroscopy.

Stereotactic co-axial projection imaging for augmented reality neuronavigation: a proof-of-concept study.

Lack of intuitiveness and poor hand-eye coordination present a major technical challenge in neurosurgical navigation. We developed an integrated dexterous stereotactic co-axial projection imaging (sCPI) system featuring orthotopic image projection for augmented reality (AR) neurosurgical navigation. The performance characteristics of the sCPI system, including projection resolution and navigation accuracy, were quantitatively verified. The resolution of the sCPI was tested with a USAF1951 resolution test chart. The stereotactic navigation accuracy of the sCPI was measured using a calibration panel with a 7×7 circle array pattern. In benchtop validation, the navigation accuracy of the sCPI and the BrainLab Kick Navigation Station was compared using a skull phantom with 8 intracranial targets. Finally, we demonstrated the potential clinical application of sCPI through a clinical trial. The resolution test showed that the resolution of the sCPI was 1.3 mm. In a stereotactic navigation accuracy test, the maximum and minimum error of the sCPI was 2.9 and 0.3 mm, and the mean error was 1.5 mm. The stereotactic navigation accuracy test also showed that the navigation error of the sCPI would increase with the pitch and yaw angle, but there was no obvious difference in navigation errors caused by different yaw directions, which meant that the navigation error is unbiased across all directions. The benchtop validation showed that the average navigation errors for the sCPI system and the Kick Navigation Station were 1.4±0.8 and 1.8±0.7 mm, the medians were 1.3 and 1.9 mm, and the average preparation times were 3 min 24 sec and 6 min 8 sec, respectively. The clinical feasibility of sCPI-assisted neurosurgical navigation was demonstrated in a clinical study. In comparison with the BrainLab device, the sCPI system required less time for preoperative preparation and enhanced the clinician experience in intraoperative visualization and navigation. The sCPI technique can be potentially used in many surgical applications for intuitive visualization of medical information and intraoperative guidance of surgical trajectories.

Endovascular catheter manometry reliability: a benchtop validation study.

Catheter manometry is used frequently in neuroendovascular surgery for assessing cerebrovascular pathology. The accuracy of pressure data with different catheter setups requires further validation. In a silicone human vascular model with a pulsatile pump, pressure measurements were taken through multiple arrangements of 2 guide catheters and 6 microcatheters. The systolic pressure, diastolic pressure, mean pressure, pulse pressure, and area under the curve of the waveform were recorded through catheters with controls at arterial blood pressure ranges. Linear regression modeling was performed, correlating transduction area and relative pulse pressure. Thresholds for acceptable accuracy were ≥ 90%. Mean pressure demonstrated < 4% variation between all 24 catheter setups and respective controls. A strong linear correlation (r2 = 0.843, p < 0.0005) between microcatheter transduction area and relative pulse pressure with a threshold of 0.50 mm2 was seen (i.e., 0.031-inch inner diameter [ID]). For guide catheters with indwelling microcatheters, there was also a strong linear correlation (r2 = 0.840, p < 0.0005) of transduction area to pulse pressure. The guide catheters with obstructing microcatheters required a transduction area over fourfold higher compared with unobstructed microcatheters (2.21 mm2 vs 0.50 mm2). Mean pressure measurements are accurate through microcatheters as small as 0.013-inch ID. Pulse pressure and waveform morphology may require a microcatheter ≥ 0.031-inch ID to achieve 90% accuracy, although the 0.027-inch ID microcatheter reached 85% accuracy. A 0.070-inch guide catheter with a microcatheter ≤ 0.042-inch outer diameter (e.g., Marksman 0.027-inch ID or smaller) allows accurate transduction of pulse pressure. Further validation of these benchtop findings is necessary before application in a clinical setting.

Usability and performance validation of an ultra-lightweight and versatile untethered robotic ankle exoskeleton

BackgroundAnkle exoskeletons can improve walking mechanics and energetics, but few untethered devices have demonstrated improved performance and usability across a wide range of users and terrains. Our goal was to design and validate a lightweight untethered ankle exoskeleton that was effective across moderate-to-high intensity ambulation in children through adults with and without walking impairment.MethodsFollowing benchtop validation of custom hardware, we assessed the group-level improvements in walking economy while wearing the device in a diverse unimpaired cohort (n = 6, body mass = 42–92 kg). We also conducted a maximal exertion experiment on a stair stepping machine in a small cohort of individuals with cerebral palsy (CP, n = 5, age = 11–33 years, GMFCS I-III, body mass = 40–71 kg). Device usability metrics (device don and setup times and System Usability Score) were assessed in both cohorts.ResultsThere was a 9.9 ± 2.6% (p = 0.012, range = 0–18%) reduction in metabolic power during exoskeleton-assisted inclined walking compared to no device in the unimpaired cohort. The cohort with CP was able to ascend 38.4 ± 23.6% (p = 0.013, range = 3–132%) more floors compared to no device without increasing metabolic power (p = 0.49) or perceived exertion (p = 0.50). Users with CP had mean device don and setup times of 3.5 ± 0.7 min and 28 ± 6 s, respectively. Unimpaired users had a mean don time of 1.5 ± 0.2 min and setup time of 14 ± 1 s. The average exoskeleton score on the System Usability Scale was 81.8 ± 8.4 (“excellent”).ConclusionsOur battery-powered ankle exoskeleton was easy to use for our participants, with initial evidence supporting effectiveness across different terrains for unimpaired adults, and children and adults with CP.Trial registration Prospectively registered at ClinicalTrials.gov (NCT04119063) on October 8, 2019.

Balloon-Augmented Leaflet Modification With Bioprosthetic or Native Aortic Scallop Intentional Laceration to Prevent Iatrogenic Coronary Artery Obstruction and Laceration of the Anterior Mitral Leaflet to Prevent Outflow Obstruction: Benchtop Validation and First In-Man Experience.

Bioprosthetic or native aortic scallop intentional laceration to prevent iatrogenic coronary artery obstruction (BASILICA) and laceration of the anterior mitral leaflet to prevent outflow obstruction (LAMPOON) reduce the risk of coronary and left ventricular outflow obstruction obstruction during transcatheter aortic valve replacement and transcatheter mitral valve replacement. Despite successful laceration, BASILICA or LAMPOON may fail to prevent obstruction caused by inadequate leaflet splay in patients having challenging anatomy such as very small valve-to-coronary distance, diffusely calcified, rigid leaflets, or undergoing transcatheter aortic valve replacement inside existing transcatheter aortic valve replacement. We describe a novel technique of balloon-augmented (BA) leaflet laceration to enhance leaflet splay. We measured the incremental leaflet splay from BA-BASILICA in vitro. From November 2019 to March 2021, 16 patients underwent BA-BASILICA and 4 BA-LAMPOON at 3 centers. BA-BASILICA increased benchtop leaflet tip splay 17%, maximum splay angle 30%, and splay area 23%, resulting in a more rounded apex and larger effective area. Sixteen patients at risk for inadequate BASILICA leaflet splay, including 4 transcatheter aortic valve replacement inside existing transcatheter aortic valve replacement, underwent BA-BASILICA. All had successful leaflet laceration. One had coronary obstruction requiring immediate orthotopic stenting. Two underwent elective orthotopic coronary stenting through the transcatheter valve cells for leaflet prolapse without coronary ischemia. There were no deaths during the procedure or at 30 days. Four patients at risk for inadequate anterior mitral leaflet splay underwent BA-LAMPOON. All had successful target leaflet laceration without left ventricular outflow obstruction obstruction or procedural death. One died within 30 days. BA leaflet laceration enhances leaflet splay in vitro and may allow transcatheter aortic valve replacement and transcatheter mitral valve replacement in patients otherwise ineligible for traditional BASILICA or LAMPOON due to challenging anatomy. Graphic Abstract: A graphic abstract is available for this article.

A Closed-loop Deep Brain Stimulation Approach for Mitigating Burst Durations in People with Parkinson's Disease.

Increased beta band synchrony has been demonstrated to be a biomarker of Parkinson's disease (PD). This abnormal synchrony can often be prolonged in long bursts of beta activity, which may interfere with normal sensorimotor processing. Previous closed loop deep brain stimulation (DBS) algorithms used averaged beta power to drive neurostimulation, which were indiscriminate to physiological (short) versus pathological (long) beta burst durations. We present a closed-loop DBS algorithm using beta burst duration as the control signal. Benchtop validation results demonstrate the feasibility of the algorithm in real-time by responding to pre-recorded STN data from a PD participant. These results provide the basis for future improved closed-loop algorithms focused on burst durations for in mitigating symptoms of PD.

Demonstration of Kinematic-Based Closed-loop Deep Brain Stimulation for Mitigating Freezing of Gait in People with Parkinson's Disease.

Impaired gait in Parkinson's disease is marked by slow, arrhythmic stepping, and often includes freezing of gait episodes where alternating stepping halts completely. Wearable inertial sensors offer a way to detect these gait changes and novel deep brain stimulation (DBS) systems can respond with clinical therapy in a real-time, closed-loop fashion. In this paper, we present two novel closed-loop DBS algorithms, one using gait arrhythmicity and one using a logistic-regression model of freezing of gait detection as control signals. Benchtop validation results demonstrate the feasibility of running these algorithms in conjunction with a closed-loop DBS system by responding to real-time human subject kinematic data and pre-recorded data from leg-worn inertial sensors from a participant with Parkinson's disease. We also present a novel control policy algorithm that changes neurostimulator frequency in response to the kinematic inputs. These results provide a foundation for further development, iteration, and testing in a clinical trial for the first closed-loop DBS algorithms using kinematic signals to therapeutically improve and understand the pathophysiological mechanisms of gait impairment in Parkinson's disease.

Improved Treatment of Postpartum Hemorrhage: Design, Development, and Bench-Top Validation of a Reusable Intrauterine Tamponade Device for Low-Resource Settings

AbstractPostpartum hemorrhage (PPH) is the leading cause of maternal mortality worldwide, and effective interventions for addressing PPH are urgently needed. Uterine balloon tamponade (UBT) is a technique to control PPH. Commercially available UBT devices are expensive and frequently require imaging technology to ensure placement. Condom-catheter uterine tamponade (C-UBT) is a technique appropriate for low-resource settings. Testing of the C-UBT is needed to better understand and optimize this technique for use in a variety of clinical settings including low-resource contexts. We describe here the design, development, and bench-top validation of a reusable C-UBT device optimized for low-resource settings. The device was tested in three differently sized uterine models using a variety of condom balloon configurations. Intrauterine wall pressure application was measured to evaluate the device capacity to apply pressure of at least 90 mmHg, estimating the mean arterial pressure within the uterine vasculature. Bench-top experimental validation of pressure exerted in uterine models demonstrated the device's capability of reaching hemostatic pressure in uterine volumes ranging from 170 to 1740 mL. Device adaptability and versatility were shown through its ability to reach the target pressure of 90 mmHg in different uterine sizes by varying balloon parameters, including condom thickness and condom configuration. The results of this study show the potential of a low-cost, reusable C-UBT device optimized to treat PPH in a variety of clinical settings, including low-resource contexts.

System and Methodology to Study and Stimulate Gastric Electrical Activity in Small Freely Behaving Animals

Aim: To develop and validate a system that can wirelessly acquire gastric slow waves and deliver electrical pulses to the stomach. Materials &amp; methods: The system is composed of a front-end and a back-end unit connected to a computer, which runs a custom-made graphical user interface. The system was validated on benchtop and in vivo studies. Results: Benchtop validation showed an appropriate frequency response to acquire slow waves. Moreover, the system was able to deliver electrical pulses at amplitudes up to ±10 mA. Slow wave activity recorded from the stomach of rats was in the range of approximately five cycles per minute (cpm). Pulses delivered to the stomach of a rat every 15 s and reduced the activity to 4 cpm during the stimulation period. Conclusion: This study reports the first wireless system and methodology that can be used to acquire slow waves and deliver electrical stimulation to the stomach of small freely behaving animals.

Monitoring and Modulating the Gastrointestinal Activity: A Wirelessly Programmable System with Impedance Measurement Capability.

This paper presents the development and benchtop validation of a system that can wirelessly acquire gastric electrical activity called slow-waves (SWs), modulate the gastrointestinal activity through stimulating with low- and high-power current pulses, and measure the tissue bio-impedance over the frequency range of 0.01 - 10 kHz. The developed system is composed of a front-end unit, and a back-end unit connected to a computer. A graphical user interface was designed in LabVIEW to process and display the recorded SWs and measured bio-impedance in real time and to configure the stimulation pulses, wirelessly. Bench-top validation showed an appropriate frequency response for analog conditioning and digitization resolution to acquire SWs. Moreover, the system was able to deliver electrical pulses at amplitudes up to ±10 mA to a maximum load of 1 kΩ. After in vivo studies, the system will be used to diagnose and treat functional gastrointestinal disorders.

P3.46: A Novel Pump Device for Recycling Gastrointestinal Fistula Losses: Design and Feasibility Study

Introduction: Enterocutaneous fistulae are a common cause of intestinal failure, and may necessitate parenteral nutrition (PN) and prolonged hospitalisation. Refeeding of fistula losses back into the distal gut is known to be beneficial, however implementation has been limited because devices are not commonly available, and manual recycling is unpleasant and labour-intensive. We present a novel device designed to enable easy and efficient chyme recycling, and report data from a first-in-human feasibility study. Methods: The novel device comprises a compact centrifugal pump that can be placed inside a standard stoma bag. The pump is connected to an intestinal feeding tube which is inserted into the distal fistula limb. The pump is activated across the stoma bag by magnetic coupling to a custom-designed hand-held driver unit, effecting intermittent bolus refeeding while avoiding contact with the stoma effluent. Five speed settings were included to handle different chyme viscosities. Nutritional, medical, psychological and human-use factors were evaluated in an initial feasibility study. Results: Following benchtop validation, the device was tested in 10 patients (1 drop-out due to unrelated obstruction; median 31d; IQR 22-50d). Indications for inclusion were remediation of high-output fistula / stoma losses (n=7), dependency on PN (n=5), and gut rehabilitation prior to restoration of continuity (n=10). A range of chyme viscosities were successfully recycled with increasing efficiency over the course of the trial, due to iterative device improvements. Patients consumed low residue diets. Once established, chyme recycling was well-tolerated in all patients, using regular boluses of up to 200 ml per episode, performed as many times as needed per day. Patients experienced a variety of benefits including reduced net losses (>65% average volumes), PN cessaton (4/5 patients, including all patients employing the final device iteration), liver function improvement, electrolyte normalisation, and improved quality of life. Of 6 patients with continuity restored at the time of reporting, none experienced post-operative ileus. Conclusions: A novel chyme recycling device was developed and feasibility confirmed in an initial study. The device is easy to use and demonstrates multiple potential benefits including weaning of PN, gut rehabilitation, improved surgical outcomes, and reduced costs of care in these complex patients. A larger efficacy trial is currently planned.

A High-Resolution Wireless Power Transfer and Data Communication System for Studying Gastric Slow Waves.

We present a wireless recording system designed for high-resolution mapping of gastric slow-wave signals. The system is composed of an implantable unit (IU), a wearable unit (WU), and a stationary unit (SU) connected to a computer. Two independent wireless data communication links consisting of IU-WU and IU-SU were developed based on near-field and far-field communication, respectively. Furthermore, the WU is capable to wirelessly recharge the IU's battery through an inductive link. For the IU-WU near-field communication, a differential pulse position data encoding algorithm with only 6.25% duty cycle, with load shift keying (LSK) modulation is developed to guarantee continuous power transmission and high data transfer rate, simultaneously. The IU sends the encoded data to the WU, and the WU can either store the data locally on a memory card or transmit them to the SU for real-time monitoring. In addition, the IU-SU far-field data communication was developed based on a RF transceiver in which the IU transmits the data directly to the SU. The benchtop validation of the system demonstrated successful IU-WU and WU-SU data transmission, while sample signals were recorded successfully at IU through saline solution and received by SU.

Design Rationale and Performance Evaluation of the Wavelet Health Wristband: Benchtop Validation of a Wrist-Worn Physiological Signal Recorder.

BackgroundWearable and connected health devices along with the recent advances in mobile and cloud computing provide a continuous, convenient-to-patient, and scalable way to collect personal health data remotely. The Wavelet Health platform and the Wavelet wristband have been developed to capture multiple physiological signals and to derive biometrics from these signals, including resting heart rate (HR), heart rate variability (HRV), and respiration rate (RR).ObjectiveThis study aimed to evaluate the accuracy of the biometric estimates and signal quality of the wristband.MethodsMeasurements collected from 35 subjects using the Wavelet wristband were compared with simultaneously recorded electrocardiogram and spirometry measurements.ResultsThe HR, HRV SD of normal-to-normal intervals, HRV root mean square of successive differences, and RR estimates matched within 0.7 beats per minute (SD 0.9), 7 milliseconds (SD 10), 11 milliseconds (SD 12), and 1 breaths per minute (SD 1) mean absolute deviation of the reference measurements, respectively. The quality of the raw plethysmography signal collected by the wristband, as determined by the harmonic-to-noise ratio, was comparable with that obtained from measurements from a finger-clip plethysmography device.ConclusionsThe accuracy of the biometric estimates and high signal quality indicate that the wristband photoplethysmography device is suitable for performing pulse wave analysis and measuring vital signs.

Design and Benchtop Validation of a Powered Knee-Ankle Prosthesis with High-Torque, Low-Impedance Actuators.

This paper describes the design of a powered knee- and-ankle transfemoral prosthetic leg, which implements high torque density actuators with low-reduction transmissions. The low reduction of the transmission coupled with a high-torque and low-speed motor creates an actuator with low mechanical impedance and high backdrivability. This style of actuation presents several possible benefits over modern actuation styles implemented in emerging robotic prosthetic legs. Such benefits include free-swinging knee motion, compliance with the ground, negligible unmodeled actuator dynamics, and greater potential for power regeneration. Benchtop validation experiments were conducted to verify some of these benefits. Backdrive and free-swinging knee tests confirm that both joints can be backdriven by small torques (~3 Nm). Bandwidth tests reveal that the actuator is capable of achieving frequencies required for walking and running. Lastly, open-loop impedance control tests prove that the intrinsic impedance and unmodeled dynamics of the actuator are sufficiently small to control joint impedance without torque feedback.

Design and Testing of a Single-Element Ultrasound Viscoelastography System for Point-of-Care Edema Quantification

Management of fluid overload in patients with end-stage renal disease represents a unique challenge to clinical practice because of the lack of accurate and objective measurement methods. Currently, peripheral edema is subjectively assessed by palpation of the patient's extremities, ostensibly a qualitative indication of tissue viscoelastic properties. New robust quantitative estimates of tissue fluid content would allow clinicians to better guide treatment, minimizing reactive treatment decision making. Ultrasound viscoelastography (UVE) can be used to estimate strain in viscoelastic tissue, deriving material properties that can help guide treatment. We are developing and testing a simple, low-cost UVE system using a single-element imaging transducer that is simpler and less computationally demanding than array-based systems. This benchtop validation study tested the feasibility of using the UVE system by measuring the mechanical properties of a tissue-mimicking material under large strains. We generated depth-dependent creep curves and viscoelastic parameter maps of time constants and elastic moduli for the Kelvin model of viscoelasticity. During testing, the UVE system performed well, with mean UVE-measured strain matching standard mechanical testing with maximum absolute errors ≤4%. Motion tracking revealed high correlation and signal-to-noise ratios, indicating that the system is reliable.

IN-HOUSE DEVELOPMENT OF UNMANNED AERIAL VEHICLE AUTOMATIC ANTENNA TRACKING SYSTEM

The control of an unmanned aerial vehicle (UAV) requires a two-way radio communication between the UAV and ground control station (GCS). This radio communication is achieved through the use of antennas as medium of recital and transmission in the data-link system. This paper presents the project of an in-house low-cost development of a UAV automatic antenna tracking system. The presentation includes the control system design, hardware and software development, system integration and testing stage. The development ended with a successfully operational automatic antenna tracking system in a benchtop testing and validation.

Wireless implantable micro-stimulation device for high frequency bilateral deep brain stimulation in freely moving mice

Although deep brain stimulation (DBS) has been proven to be an effective treatment for several neuropsychiatric disorders, such as Parkinson's disease, the underlying working mechanisms are still largely unknown. Behavioral animal models are essential in examining the working mechanisms of DBS and especially mouse models are necessary to investigate the genetic component underlying specific behaviors related to psychiatric diseases. Unfortunately, currently available stimulation devices are unsuitable to test behavior in freely-moving mice. As such, no DBS studies in behaving mice have been reported thus far. In order to overcome this limitation we have developed a new light-weight wireless implantable micro stimulator device for mice that delivers biphasic pulse patterns to two individual electrode pairs, mimicking partly the clinical situation. This paper describes in detail the bench-top validation and in vivo implementation of this device. The results in this study indicate that the wireless implantable stimulator in mice reliably delivers continuous bilateral stimulation, importantly, does not restrict the animals mobility and hygiene (grooming behavior). In vivo testing furthermore showed that stimulation of the mice ventral striatum yields similar results as previously shown by others in rats where conventional deep brain stimulation techniques were used. This newly designed device can now be used in the highly needed DBS behavioral studies in mice, to further investigate the underlying mechanisms of DBS in behavioral animal models for psychiatric disorders.