Soft electrochemical bubble actuator with liquid metal electrode using an embodied hydrogel pneumatic source.

Soft pneumatic actuators-such as those used for soft robotics-achieve actuation by inflation of pneumatic chambers. Here, we report the use of the electrochemical reduction of water to generate gaseous products that inflate pneumatic chambers. Whereas conventional pneumatic actuators typically utilize bulky mechanical pumps, the approach here utilizes only electricity. In contrast to dielectric actuators, which require ∼kV to actuate, the electrochemical approach uses a potential of a few volts. The applied potential converts liquid water-a safe, abundant, and cheap fuel-into hydrogen gas. Since the chambers are constructed of hydrogel, the body of the actuator provides an abundant supply of water that ultimately converts to gas. The use of liquid metal for the electrode makes the entire device soft and ensures intimate contact between the chamber walls and the electrode during inflation. The device can inflate in tens of seconds, which is slower than other pneumatic approaches, but much faster than actuating hydrogels via principles of swelling. The actuation volume can be predicted and controlled based on the input parameters such as time and voltage. The actuation shape and position can also be controlled by the position of the electrodes and the geometry of the device. Such actuators have the potential to make tether-less (pump-free), electrically-controlled soft devices that can even operate underwater.

A Soft Variable-Area Electrical-Double-Layer Energy Harvester.

The technological promise of soft devices-wearable electronics, implantables, soft robotics, sensors-has accelerated the demand for deformable energy sources. Devices that can convert mechanical energy to electrical energy can enable self-powered, tetherless, and sustainable devices. This work presents a completely soft and stretchable (>400% strain) energy harvester based on variable-area electrical-double-layer (EDL) capacitors (≈40 µF cm-2 ). Mechanically varying the EDL area, and thus the capacitance, disrupts equilibrium and generates a driving force for charge movement through an external circuit. Prior EDL capacitors varied the contact area by depressing water droplets between rigid electrodes. In contrast, here, the harvester consists of liquid-metal electrodes encased in a hydrogel. Deforming the device by ≈25% strain generates a power density ≈0.5 mW m-2 . This unconventional approach is attractive because: (1) it does not need an external voltage supply to provide charge; (2) the electrodes themselves deform; and (3) it can work under various modes of deformation such as pressing, stretching, bending, and twisting. The unique ability of the harvester to operate underwater shows promising applications in wearables that contact sweat, underwater sensing, and blue energy harvesting.

Complications with Hair Transplantation.

Most complications associated with hair transplant surgery are usually preventable and most often arise as a consequence of poor planning or faulty surgical technique. Patients should be evaluated for having realistic goals and a pattern that is amenable to aesthetic restoration. A good treatment plan must consider the potential for future hair loss. Well-informed patients who carefully follow instructions and take an active role in the postoperative recovery process minimize the chance of patient-controlled complications. This article discusses potential complications associated with hair restoration surgery, and the roles of the patient and physician in decreasing the risk of complications.

Glomus faciale tumors: A report of 3 cases and literature review.

Our objectives in reporting this case series are to familiarize readers with the rare occurrence of paragangliomas originating along the facial nerve and to provide a literature review. We describe 3 such cases that occurred at our tertiary care academic medical center. Two women and 1 man presented with a tumor adjacent to the vertical segment of the facial nerve. The first patient, a 48-year-old woman, presented with what appeared to be a parotid tumor at the stylomastoid foramen; she underwent a parotidectomy, transmastoid facial nerve decompression, and a shave biopsy of the tumor. The second patient, a 66-year-old man, underwent surgery via a postauricular infratemporal fossa approach, and a complete tumor resection was achieved. The third patient, a 56-year-old woman, presented with a middle ear mass; she underwent complete tumor removal through a transmastoid transcanal approach. All 3 patients exhibited normal facial nerve function both before and after surgery. Paragangliomas of the facial nerve are extremely rare, and their signs and symptoms are unlike those of any other temporal bone glomus tumors. Management options include surgical resection, radiologic surveillance, and radiotherapy. The facial nerve can be spared in selected cases.

Revision Functional Surgery: Salvaging Function.

Reduction rhinoplasty techniques include maneuvers that weaken the nasal osseocartilaginous framework. The structurally compromised anatomy remaining after reductive surgery may be left with inadequate strength to withstand postoperative contractile forces. Significant aesthetic and functional deformities requiring revision rhinoplasty may develop. This article reviews common causes of nasal obstruction after primary rhinoplasty. The discussion of etiology is based on both the anatomic description of nasal subsites (middle vault and lateral walls) as well as an explanation of why certain techniques lead to functional problems in these areas. Revision rhinoplasty techniques for correcting these problems are discussed in detail.

Facial reanimation according to the postresection defect during lateral skull base surgery.

The vast majority of benign tumors of the cerebellopontine angle, temporal bone, and parotid gland can be successfully resected without permanent injury to the facial nerve. Malignant tumors or recurrent disease may require facial nerve sacrifice, especially if preoperative facial paresis is present. This article will present case examples of the various methods to reconstruct facial animation after lateral skull base resections that require sacrifice of cranial nerve VII, and the associated mimetic facial musculature. Facial mimetic outcome after reanimation was graded using the House-Brackmann scale. Primary neurorrhaphy or interposition grafting may be performed when both the proximal and distal portions of the facial nerve are available and viable facial musculature is present. If only the distal facial nerve and viable facial musculature are available, a split hypoglossal to facial nerve anastomosis is used. A proximal facial nerve to microvascular free flap is performed when the proximal facial nerve is available without distal nerve or viable musculature. A cross-facial to microvascular free flap is performed when the proximal and distal facial nerve and facial musculature are unavailable. The above methods resulted in a House-Brackmann score of III/VI in all case examples postoperatively. The method of facial reanimation used depends on the availability of viable proximal facial nerve, the location of healthy, tumor-free distal facial nerve, and the presence of functioning facial mimetic musculature.

The economic impact of revision otologic surgery.

Revision otologic surgery places a significant economic burden on patients and the healthcare system. We conducted a retrospective chart analysis to estimate the economic impact of revision canal-wall-down (CWD) mastoidectomy. We reviewed the medical records of all 189 adults who had undergone CWD mastoidectomy performed by the senior author between June 2006 and August 2011 at Loyola University Medical Center in Maywood, Ill. Institutional charges and collections for all patients were extrapolated to estimate the overall healthcare cost of revision surgery in Illinois and at the national level. Of the 189 CWD mastoidectomies, 89 were primary and 100 were revision procedures. The total charge for the revision cases was $2,783,700, and the net reimbursement (collections) was $846,289 (30.4%). Using Illinois Hospital Association data, we estimated that reimbursement for 387 revision CWD mastoidectomies that had been performed in fiscal year 2011 was nearly $3.3 million. By extrapolating our data to the national level, we estimated that 9,214 patients underwent revision CWD mastoidectomy in the United States during 2011, which cost the national healthcare system roughly $76 million, not including lost wages and productivity. Known causes of failed CWD mastoidectomies that often result in revision surgery include an inadequate meatoplasty, a facial ridge that is too high, residual diseased air cells, and recurrent cholesteatoma. A better understanding of these factors can reduce the need for revision surgery, which could have a positive impact on the economic strain related to this procedure at the local, state, and national levels.

Immediate postoperative imaging after uncomplicated endoscopic approach to the anterior skull base: is it necessary?

BACKGROUND: Postoperative imaging is frequently performed to assess for intracranial complications following anterior skull base (ASB) surgery. However, there is little data to suggest that radiologic studies change the management of complications. In this study, the utility of postoperative imaging within 72 hours after uncomplicated ASB surgery was examined. METHODS: A retrospective review was conducted of 143 patients who underwent endoscopic ASB surgery between 2007 and 2013 at Loyola University Medical Center. The main outcomes measures included the ability of head computed tomography (CT) scan to identify postoperative complications and hallmark symptoms associated with complications. RESULTS: Seventy-nine patients underwent postoperative imaging within 72 hours of the initial surgery. The most common finding was pneumocephalus (35/79; 44%). Expanding pneumocephalus requiring surgical intervention developed in 3 cases. Cerebrospinal fluid (CSF) leak was the most common complication, occurring in 22 of 143 (15%) of the patients. Of the 24 patients who developed a postoperative complication, all had clinical signs or symptoms indicative of the need for surgical or medical intervention. The positive predictive value for a head CT scan to detect a complication was 12%, negative predictive value was 92%, and sensitivity and specificity were 63% and 48%, respectively. CONCLUSION: Routine postoperative imaging may be unnecessary after uncomplicated endoscopic ASB surgery because (1) it may not alter patient management; (2) it may not detect the most common complication (CSF leak); and (3) when imaging is positive, the patient has clinical symptoms suggesting a need for intervention.