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Arrays of carbon nanotube (CNT) microelectrodes (nominal geometric surface areas 20-200 μm(2)) were fabricated by photolithography with chemical vapor deposition of randomly oriented CNTs. Raman spectroscopy showed strong peak intensities in both G and D bands (G/D = 0.86), indicative of significant disorder in the graphitic layers of the randomly oriented CNTs. The impedance spectra of gold and CNT microelectrodes were compared using equivalent circuit models. Compared to planar gold surfaces, pristine nanotubes lowered the overall electrode impedance at 1 kHz by 75%, while nanotubes treated in O(2) plasma reduced the impedance by 95%. Cyclic voltammetry in potassium ferricyanide showed potential peak separations of 133 and 198 mV for gold and carbon nanotube electrodes, respectively. The interaction of cultured cardiac myocytes with randomly oriented and vertically aligned CNTs was investigated by the sectioning of myocytes using focused-ion-beam milling. Vertically aligned nanotubes deposited by plasma-enhanced chemical vapor deposition (PECVD) were observed to penetrate the membrane of neonatal-rat ventricular myocytes, while randomly oriented CNTs remained external to the cells. These results demonstrated that CNT electrodes can be leveraged to reduce impedance and enhance biological interfaces for microelectrodes of subcellular size.

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Background Robotic surgical platforms have seen increased use amongst minimally invasive gastrointestinal surgeons1. However, these systems still suffer from lack of haptic feedback, which results in exertion of excessive force, often leading to suture failures2. This work catalogs tensile strength and failure load amongst commonly used sutures in an effort to prevent robotic surgical consoles from exceeding identified thresholds. Trials were thus conducted on common sutures varying in material type, gauge size, rate of pulling force, and method of applied force. Methods Polydioxane, Silk, Vicryl, and Prolene, gauges 5-0 to 1-0, were pulled till failure using a commercial mechanical testing system. 2-0 and 3-0 sutures were further tested for the effect of pullrate on failure load at rates of 50 mm/min, 200 mm/min, and 400 mm/min. 3-0 sutures were also pulled till failure using a da Vinci robotic surgical system in un-looped, looped, and at the needle body arrangements. Results Generally, Vicryl and PDS sutures had the highest mechanical strength (47 to 179 kN/cm2), while Silk had the lowest (40 to 106 kN/cm2). Larger diameter sutures withstand higher total force, but finer gauges consistently show higher force per unit area. The difference between material types becomes increasingly significant as the diameters decrease. Comparisons of identical suture materials and gauges show 27–50% improvement in the tensile strength over data obtained in 19853. No significant differences were observed when sutures were pulled at different rates. Reduction of suture strength appeared to be strongly affected by the technique used to manipulate the suture. Conclusions Availability of suture tensile strength and failure load data will help define software safety protocols for alerting a surgeon prior to suture failure during robotic surgery. Awareness of suture strength weakening with direct instrument manipulation may lead to development of better techniques to further reduce intraoperative suture breakage.

The number of procedures performed with robotic surgery may exceed one million globally in 2018. The continual lack of haptic feedback, however, forces surgeons to rely on visual cues in order to avoid breaking sutures due to excessive applied force. To mitigate this problem, the authors developed and validated a novel grasper-integrated system with biaxial shear sensing and haptic feedback to warn the operator prior to anticipated suture breakage. Furthermore, the design enables facile suture manipulation without a degradation in efficacy, as determined via measured tightness of resulting suture knots. Biaxial shear sensors were integrated with a da Vinci robotic surgical system. Novice subjects (n =17) were instructed to tighten 10 knots, five times with the Haptic Feedback System (HFS) enabled, five times with the system disabled. Seven suture failures occurred in trials with HFS enabled while seventeen occurred in trials without feedback. The biaxial shear sensing system reduced the incidence of suture failure by 59% (p = 0.0371). It also resulted in 25% lower average applied force in comparison to trials without feedback (p = 0.00034), which is relevant because average force was observed to play a role in suture breakage (p = 0.03925). An observed 55% decrease in standard deviation of knot quality when using the HFS also indicates an improvement in consistency when using the feedback system. These results suggest this system may improve outcomes related to knot tying tasks in robotic surgery and reduce instances of suture failure while not degrading the quality of knots produced.

Recent advancements in microelectromechanical system (MEMS) fabrication techniques have enabled the batch-fabrication of quadrupole MEMS electromagnets producing 100 mT-scale field across sub-mm gaps with the potential for transformational advances in the field of compact high performance charged particle focusing and steering optics. The footprint of these in-vacuum focusing and steering optics can be as small as 3 mm × 3 mm × 0.5 mm. The low electromagnet impedance (58 mΩ, 32 nH per pole) facilitates power-efficient operation and continuous or low duty cycle operation, and the individually controlled electromagnets allow combined dipole-quadrupole fields. Here we report on an experiment where these miniature devices have been used to focus and steer a 34 keV electron beam from a DC photogun, demonstrating the first application of magnetic MEMS to particle beam focusing.

Although surgical robotic systems provide several advantages over conventional minimally invasive techniques, they are limited by a lack of tactile feedback. Recent research efforts have successfully integrated tactile feedback components onto surgical robotic systems, and have shown significant improvement to surgical control during in vitro experiments. The primary barrier to the adoption of tactile feedback in clinical use is the unavailability of suitable force sensing technologies. This paper describes the design and fabrication of a thin-film capacitive force sensor array that is intended for integration with tactile feedback systems. This capacitive force sensing technology could provide precise, high-sensitivity, real-time responses to both static and dynamic loads. Capacitive force sensors were designed to operate with optimal sensitivity and dynamic range in the range of forces typical in minimally invasive surgery (0-40 N). Initial results validate the fabrication of these capacitive force-sensing arrays. We report 16.3 pF and 146 pF for 1-mm(2) and 9-mm(2) capacitive areas, respectively, whose values are within 3% of theoretical predictions.