Erratum: Publisher's Note: "Contrast-enhanced ultrasound tracking of helical propellers with acoustic phase analysis and comparison with color Doppler" [APL Bioeng. 6, 036102 (2022)].

[This corrects the article DOI: 10.1063/5.0097145.].

Contrast-enhanced ultrasound tracking of helical propellers with acoustic phase analysis and comparison with color Doppler.

Medical microrobots (MRs) hold the potential to radically transform several interventional procedures. However, to guarantee therapy success when operating in hard-to-reach body districts, a precise and robust imaging strategy is required for monitoring and controlling MRs in real-time. Ultrasound (US) may represent a powerful technology, but MRs' visibility with US needs to be improved, especially when targeting echogenic tissues. In this context, motions of MRs have been exploited to enhance their contrast, e.g., by Doppler imaging. To exploit a more selective contrast-enhancement mechanism, in this study, we analyze in detail the characteristic motions of one of the most widely adopted MR concepts, i.e., the helical propeller, with a particular focus on its interactions with the backscattered US waves. We combine a kinematic analysis of the propeller 3D motion with an US acoustic phase analysis (APA) performed on the raw radio frequency US data in order to improve imaging and tracking in bio-mimicking environments. We validated our US-APA approach in diverse scenarios, aimed at simulating realistic in vivo conditions, and compared the results to those obtained with standard US Doppler. Overall, our technique provided a precise and stable feedback to visualize and track helical propellers in echogenic tissues (chicken breast), tissue-mimicking phantoms with bifurcated lumina, and in the presence of different motion disturbances (e.g., physiological flows and tissue motions), where standard Doppler showed poor performance. Furthermore, the proposed US-APA technique allowed for real-time estimation of MR velocity, where standard Doppler failed.

Fabrication and characterization of AlN-based flexible piezoelectric pressure sensor integrated into an implantable artificial pancreas.

This study reports on the fabrication and characterization of an event detection subsystem composed of a flexible piezoelectric pressure sensor and the electronic interface to be integrated into an implantable artificial pancreas (IAP) for diabetic patients. The developed sensor is made of an AlN layer, sandwiched between two Ti electrodes, sputtered on Kapton substrate, with a preferential orientation along c-axis which guarantees the best piezoelectric response. The IAP is made of an intestinal wall-interfaced refilling module, able to dock an ingestible insulin capsule. A linearly actuated needle punches the duodenum tissue and then the PDMS capsule to transfer the insulin to an implanted reservoir. The device is located at the connection of the needle with the linear actuator to reliably detect the occurred punching of the insulin-filled capsule. Finite Element Analysis (FEA) simulations were performed to evaluate the piezoelectric charge generated for increasing loads in the range of interest, applied on both the sensor full-area and footprint area of the Hamilton needle used for the capsule punching. The sensor-interface circuit was simulated to estimate the output voltage that can be obtained in real operating conditions. The characterization results confirmed a high device sensitivity during the punching, in the low forces (0-4 N) and low actuator speed (2-3 mm/s) ranges of interest, meeting the requirement of the research objective. The choice of a piezoelectric pressure sensor is particularly strategic in the medical field due to the request of self-powered implantable devices which do not need any external power source to output a signal and harvest energy from natural sources around the patient.

Polydimethylsiloxane films doped with NdFeB powder: magnetic characterization and potential applications in biomedical engineering and microrobotics.

This work reports the fabrication, magnetic characterization and controlled navigation of film-shaped microrobots consisting of a polydimethylsiloxane-NdFeB powder composite material. The fabrication process relies on spin-coating deposition, powder orientation and permanent magnetization. Films with different powder concentrations (10 %, 30 %, 50 % and 70 % w/w) were fabricated and characterized in terms of magnetic properties and magnetic navigation performances (by exploiting an electromagnet-based platform). Standardized data are provided, thus enabling the exploitation of these composite materials in a wide range of applications, from MEMS/microrobot development to biomedical systems. Finally, the possibility to microfabricate free-standing polymeric structures and the biocompatibility of the proposed composite materials is demonstrated.

Magnetically driven microrobotic system for cancer cell manipulation.

Lab-on-a-chip applications, such as single cell manipulation and targeted delivery of chemicals, could greatly benefit from mobile untethered microdevices able to move in fluidic environments by using magnetic fields. In this paper a magnetically driven microrobotic system enabling the controlled locomotion of objects placed at the air/liquid interface is proposed and exploited for cell manipulation. In particular authors report the design, fabrication and testing of a polymeric thin film-based magnetic microrobot (called "FilmBot") used as a support for navigating cancer cells. By finely controlling magnetic film locomotion, it is possible to navigate the cells by exploiting their adhesion to the film without affecting their integrity. Preliminary in vitro tests demonstrated that the magnetic thin film is able to act as substrate for T24 bladder cancer cells without affecting their viability and that film locomotion can be magnetically controlled (with a magnetic field and a gradient of 6 mT and 0.6 T/m, respectively) along specific directions, with a mean speed of about 3 mm/s.

[Continuous venous infusion of buprenorphine with autonomous elastomeric system in the control of postoperative pain]. / Infusione venosa continua di buprenorfina mediante sistema elastomerico autonomo nel controllo del dolore postoperatorio.

We herein evaluated the analgesic effectiveness of low doses of buprenorphine with or without a primer and the practicality and usefulness of a constant flow disposable infusion set (Infusor Baxter 2 ml/h). Our series consists of 300 patients, seen between January 1992 and December 1993, randomly distributed in three groups of 100 patients each. All patients were informed before operation about the use of pain Visual Analogical Scale (VAS) and how the infusor works. At the end of the operation all patients had an infusor positioned with a 0.01 mg/kg supplied of buprenorphine diluted to 60 ml with Ringer's Lactate solution. In addition to this, group B patients received an i.v. primer of 0.003 mg/kg of buprenorphine diluted to 10 ml with saline solution and group C patients received an i.v. primer of 0.5 mg/kg of ketorolac diluted to 10 ml with saline solution. VAS, systolic arterial pressure, diastolic arterial pressure, heart rate, respiratory rate, request of analgesics and side effects were evaluated at one hour (T0), six hours (T1), 12 hours (T2), 24 hours (T3) and 36 hours (T4) after operation. Group B and C patients showed significant reduction in VAS compared to group A patients at T0 and T1 but the difference disappeared starting from T2. Group B and C patients showed blood pressure, heart rate and respiratory rate values significantly reduced compared to group A patients at T0 and T1. Such values however then stabilized. Side effects encountered were nausea and vomiting in different percentages in the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

[Postoperative analgesia: peridural morphine versus sublingual buprenorphine. Comparative clinical study]. / Analgesia postoperatoria: morfina per via peridurale vs buprenorfina per via sublinguale. Studio clinico comparativo.

The authors herein present their personal series on the clinical evaluation of the analgesic efficacy of 2 opiodes, peridural morphine hydrochloride (0.5 mg/kg) administered to group A patients, and sublingual buprenorphine (0.4 mg) administered to group B patients in the management of post-operative pain in major abdominal surgery. The study was conducted on 44 patients, both male and female, classified as ASA II and III. Statistical analysis of cardiovascular parameters (BP and cardiac frequency), respiratory frequency and pain score showed an overlapping progression among the two groups. Spontaneous pain decreased significantly to zero at T6 (p < 0.001). However, the necessity to administer buprenorphine more frequently after the sixth hour and the consequent increase in side effects, lead us to believe that the method used for group A patients is more advantageous.

[Buprenorphine as preanesthetic medication in peridural anesthesia]. / La buprenorfina come farmaco preanestetico in anestesia peridurale.

Buprenorphine was used as a preanesthetic drug for peridural anaesthesia. The aim of the study was therefore to evaluate the sedative/anxiolitic activity of this drug as compared to prometazine and diazepam. Two hundred male patients, divided into two groups (A and B), who were to undergo urological surgery under peripheral anesthesia, were included in the study: L2/L3 or L3/L4 epidural block. The group A patients were premedicated with buprenorphine; the group B patients received traditional anesthetic. The following factors were evaluated: the course of the AP and CF, the state of intraoperative sedation, the presence of side effects and data obtained, elaborated with a statistical test constructed to compare the percentages in two independent samples. There were no statistically significant variations of the AP and CF in the two groups. Additional sedatives were administered to 56.2% of the patients in group B and to only 27.1% in group A, premedicated with buprenorphine. Thirty seven percent of the group A patients and 10% of the group B patients presented preoperative nausea. The authors believe that the buprenorphine/atrophine association should be encouraged for pre-anesthesia when operations in peridural anesthesia are to be conducted, as it provides a state of constant sedation, avoiding rather ineffective pharmacological mixtures.