A mechanics-based approach to realize high-force capacity electroadhesives for robots.

Materials with electroprogrammable stiffness and adhesion can enhance the performance of robotic systems, but achieving large changes in stiffness and adhesive forces in real time is an ongoing challenge. Electroadhesive clutches can rapidly adhere high stiffness elements, although their low force capacities and high activation voltages have limited their applications. A major challenge in realizing stronger electroadhesive clutches is that current parallel plate models poorly predict clutch force capacity and cannot be used to design better devices. Here, we use a fracture mechanics framework to understand the relationship between clutch design and force capacity. We demonstrate and verify a mechanics-based model that predicts clutch performance across multiple geometries and applied voltages. On the basis of this approach, we build a clutch with 63 times the force capacity per unit electrostatic force of state-of-the-art electroadhesive clutches. Last, we demonstrate the ability of our electroadhesives to increase the load capacity of a soft, pneumatic finger by a factor of 27 times compared with a finger without an electroadhesive.

Materials with Electroprogrammable Stiffness.

Stiffness is a mechanical property of vital importance to any material system and is typically considered a static quantity. Recent work, however, has shown that novel materials with programmable stiffness can enhance the performance and simplify the design of engineered systems, such as morphing wings, robotic grippers, and wearable exoskeletons. For many of these applications, the ability to program stiffness with electrical activation is advantageous because of the natural compatibility with electrical sensing, control, and power networks ubiquitous in autonomous machines and robots. The numerous applications for materials with electrically driven stiffness modulation has driven a rapid increase in the number of publications in this field. Here, a comprehensive review of the available materials that realize electroprogrammable stiffness is provided, showing that all current approaches can be categorized as using electrostatics or electrically activated phase changes, and summarizing the advantages, limitations, and applications of these materials. Finally, a perspective identifies state-of-the-art trends and an outlook of future opportunities for the development and use of materials with electroprogrammable stiffness.

The INSPIRE Comparative Cost Study: 12-Month Health Economic and Clinical Outcomes Associated with Hysterectomy, Myomectomy, and Treatment with the Sonata System.

PURPOSE: The INSPIRE study compared perioperative and 12-month health economic and clinical outcomes associated with hysterectomy, myomectomy, and sonography-guided transcervical fibroid ablation (TFA) using the Sonata® system. PATIENTS AND METHODS: Cost and health care resource utilization (HCRU) data for TFA were obtained from a prospective, multicenter, single-arm clinical trial. Data for hysterectomy and myomectomy arms were derived from the Truven Health MarketScan commercial payer claims database. The Truven data was used to determine health economic outcomes and costs for the hysterectomy and myomectomy arms. For each arm, payer perspective costs were estimated from the available charge and HCRU data. RESULTS: TFA with Sonata had significantly lower mean length of stay (LOS) of 5 hrs versus hysterectomy (73 hrs) or myomectomy (79 hrs; all p< 0.001). The average payer cost for TFA treatment, including the associated postoperative HCRU was $8,941. This was significantly lower compared to hysterectomy ($24,156) and myomectomy ($22,784; all p< 0.001). In the TFA arm, there were no device- or procedure-related costs associated with complications during the peri- or postoperative time frame. TFA subjects had significantly lower costs associated with complications, prescription medications, and radiology. CONCLUSION: Compared to hysterectomy and myomectomy, TFA treatment with the Sonata system was associated with significantly lower index procedure cost, complication cost, and LOS, contributing to a lower total payer cost through 12 months.

Elastomeric passive transmission for autonomous force-velocity adaptation applied to 3D-printed prosthetics.

The force, speed, dexterity, and compact size required of prosthetic hands present extreme design challenges for engineers. Current prosthetics rely on high-quality motors to achieve adequate precision, force, and speed in a small enough form factor with the trade-off of high cost. We present a simple, compact, and cost-effective continuously variable transmission produced via projection stereolithography. Our transmission, which we call an elastomeric passive transmission (EPT), is a polyurethane composite cylinder that autonomously adjusts its radius based on the tension in a wire spooled around it. We integrated six of these EPTs into a three-dimensionally printed soft prosthetic hand with six active degrees of freedom. Our EPTs provided the prosthetic hand with about three times increase in grip force without compromising flexion speed. This increased performance leads to finger closing speeds of ~0.5 seconds (average radial velocity, ~180 degrees second-1) and maximum fingertip forces of ~32 newtons per finger.

Sensitivity of myoma imaging using laparoscopic ultrasound compared with magnetic resonance imaging and transvaginal ultrasound.

STUDY OBJECTIVE: To determine the efficacy of laparoscopic ultrasound (LUS) as compared with contrast-enhanced magnetic resonance imaging (CE-MRI) and transvaginal ultrasound (TVUS) in detection of uterine myomas. DESIGN: Retrospective study of imaging methods used in a trial of LUS-guided radiofrequency volumetric thermal ablation in women with symptomatic myomas (Canadian Task Force classification II-2). SETTING: Eleven medical university or private outpatient surgery clinics in the United States (nine sites) and Latin America (two sites). PATIENTS: One hundred thirty-five women with symptomatic myomas and objectively confirmed moderate to severe heavy menstrual bleeding. INTERVENTIONS: LUS-guided radiofrequency volumetric thermal ablation of myomas. MEASUREMENTS AND MAIN RESULTS: Preoperative TVUS scans and CE-MRIs were read at each site, and all CE-MRIs were read by a central reader. LUS-guided scans were obtained intraoperatively by each surgeon by mapping the uterus just before radiofrequency volumetric thermal ablation. The imaging methods and their yields in terms of number of myomas found per subject were as follows: TVUS, 403 myomas (mean [SD] 3 [1.8]; range, 1-8); site CE-MRI, 562 myomas (4.2 [3.8]; range, 1-18); central reader, 619 myomas (4.6 [3.7]; range, 0-20); and LUS, 818 myomas (6.1 [4.9]; range, 1-29) (p < .001). LUS was superior to TVUS, CE-MRI, and the central reader for detection of small (≤1 cm(3)) myomas. Most imaged myomas were intramural: 197 (50.9%) by TVUS, 298 (55.5%) by site CE-MRI, 290 (48.7%) by the central reader, and 386 (48.5%) by LUS. CONCLUSION: Compared with CE-MRI and TVUS, LUS demonstrates the most myomas, regardless of size or type.

Outpatient procedure for the treatment and relief of symptomatic uterine myomas.

OBJECTIVE: To estimate the safety and efficacy of laparoscopic ultrasound-guided radiofrequency volumetric thermal ablation of uterine myomas in symptomatic women. METHODS: A cohort of 135 premenopausal symptomatic women with uterine myomas, uteri 14 weeks of gestation-sized or less with no single myoma exceeding 7 cm, and objectively confirmed heavy menstrual bleeding participated in this prospective, international trial of outpatient laparoscopic ultrasound-guided radiofrequency volumetric thermal ablation. Bleeding outcomes were measured by alkaline hematin analysis at baseline and again at 3, 6, and 12 months posttreatment. Validated quality-of-life and patient satisfaction scales and objective measurements of uterine and myoma volume were conducted at 3, 6, and 12 months. RESULTS: The mean baseline menstrual blood loss of women in the full analysis set (n=127) was 272.7±82.3 mL. At 3-, 6-, and 12-month follow-ups, mean alkaline hematin and associated menstrual blood loss decreased from baseline levels by 31.8%, 40.7%, and 38.3%, respectively (P<.001, paired t test). Symptom severity decreased from a baseline mean transformed score of 61.1 to 26.6 at 12 months postprocedure (P<.001, paired t test). Health-related quality of life improved from a mean transformed score of 37.3 at baseline to 79.5 at 12 months (P<.001, paired t test). At 12 months postprocedure, total mean myoma volume decreased from baseline by 45.1% (measured by magnetic resonance imaging). There was one serious adverse event (one of 135 [0.7%]) requiring readmission 5 weeks postprocedure and one surgical reintervention for persistent bleeding. Ninety-four percent of the women reported satisfaction with the treatment. CONCLUSION: Radiofrequency volumetric thermal ablation of myomas is well tolerated and results in rapid recovery, high patient satisfaction, improved quality of life, and effective symptom relief. CLINICAL TRIAL REGISTRATION: : ClinicalTrials.gov, www.clinicaltrials.gov, NCT00874029. LEVEL OF EVIDENCE: II.

Ovarian transplantation between monozygotic twins discordant for premature ovarian failure.

Monozygotic 24-year-old twins presented with discordant ovarian function. One had had premature ovarian failure at the age of 14 years, whereas her sister had normal ovaries and three naturally conceived children. After unsuccessful egg-donation therapy, the sterile twin received a transplant of ovarian cortical tissue from her sister by means of a minilaparotomy. Within three months after transplantation, the recipient's cycles resumed and serum gonadotropin levels fell to the normal range. During the second cycle, she conceived, and her pregnancy progressed uneventfully. At 38 weeks' gestation, she delivered a healthy-appearing female infant.