Large-Area 3D Printable Soft Electronic Skin for Biomedical Applications.

Soft electronic skin (soft-e-skin) capable of sensing touch and pressure similar to human skin is essential in many applications, including robotics, healthcare, and augmented reality. However, most of the research effort on soft-e-skin was confined to the lab-scale demonstration. Several hurdles remain challenging, such as highly complex and expensive fabrication processes, instability in long-term use, and difficulty producing large areas and mass production. Here, we present a robust 3D printable large-area electronic skin made of a soft and resilient polymer capable of detecting touch and load, and bending with extreme sensitivity (up to 150 kPa-1) to touch and load, 750 times higher than earlier work. The soft-e-skin shows excellent long-term stability and consistent performance up to almost a year. In addition, we describe a fabrication process capable of producing large areas and in large numbers, yet is cost-effective. The soft-e-skin consists of a uniquely designed optical waveguide and a layer of a soft membrane with an array of soft structures which work as passive sensing nodes. The use of a soft structure gives the liberty of stretching to the soft-e-skin without considering the disjoints among the sensing nodes. We have shown the functioning of the soft-e-skin under various conditions.

Complex Obstetric Perineal Injury Reconstruction Using Antropyloric Valve Transposition

Despite significant advancements in the field of medicine, management of complex obstetric perineal injuries remains a challenge. Although several surgical techniques have been described, no techniques have provided satisfactory long-term results. Recently, a perineal transposed antropyloric valve has been used for anorectal reconstruction in patients with damaged or excised anal sphincters. We describe this technique in the case of complex obstetric perineal trauma with extensive tissue loss, presenting with end stage fecal incontinence. The functional outcome after this procedure was evaluated. The patient tolerated the surgery well, and there were no procedure-related upper gastrointestinal disturbances. Short-term functional outcomes were encouraging. At the 36-month follow-up, the patient’s neoanal resting and squeeze pressures were 50 and 70 mmHg, respectively. The postoperative St. Mark’s incontinence score was 7. Perineal antropyloric valve transposition is feasible and can be successfully applied in the management of end-stage fecal incontinence associated with complex obstetric perineal injury.

Generation of Aspherical Optical Lenses via Arrested Spreading and Pinching of a Cross-Linkable Liquid.

Aspherical optical lenses with spatially varying curvature are desired for capturing high quality, aberration free images in numerous optical applications. Conventionally such lenses are prepared by multistep top-down processes which are expensive, time-consuming, and prone to high failure rate. In this context, an alternate method is presented here based on arrested spreading of a sessile drop of a transparent, cross-linkable polymeric liquid on a solid substrate heated to an elevated temperature. Whereas surface tension driven flow tends to render it spherical, rapid cross-linking arrests such flow so that nonequilibrium aspherical shapes are attained. It is possible to tune also the initial state of the drop via delayed pinching of a liquid cylinder which precedes its release on the substrate. This method has led to the generation of a wide variety of optical lenses, ranging from spherical plano convex to superspherical solid immersion to exotic lenses not achieved via conventional methods.

Molecularly imprinted polyaniline-polyvinyl sulphonic acid composite based sensor for para-nitrophenol detection.

We report results of the studies relating to the fabrication and characterization of a conducting polymer based molecularly imprinted para-nitrophenol (PNP) sensor. A water pollutant, para-nitrophenol is electrochemically imprinted with polyvinyl sulphonic acid (PVSA) doped polyaniline onto indium tin oxide (ITO) glass substrate. This PNP imprinted electrode (PNPI-PANI-PVSA/ITO) prepared via chronopotentiometric polymerization and over-oxidation is characterized by Fourier transform infra-red spectroscopy (FT-IR), UV-visible (UV-vis) spectroscopy, contact angle (CA), scanning electron microscopy (SEM), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) studies. The response studies of PNPI-PANI-PVSA/ITO electrode carried out using DPV reveal a lower detection limit of 1×10(-3) mM, improved sensitivity as 1.5×10(-3) A mM(-1) and stability of 45 days. The PNPI-PANI-PVSA/ITO electrode shows good precision with relative standard deviation of 2.1% and good reproducibility with standard deviation of 3.78%.

Feasibility of Neurovascular Antropylorus Perineal Transposition With Pudendal Nerve Anastomosis Following Anorectal Excision: A Cadaveric Study for Neoanal Reconstruction

PURPOSE: Perineal transposition of the antropyloric valve following an anorectal excision as a substitute for a permanent colostomy has recently been reported in humans. However, the problem of neural control still remains in these patients. Our aim herein was to study the anatomical feasibility of an anastomosis between the pudendal nerve branches (inferior rectal nerve) innervating the external anal sphincter and the anterior vagal branches of the perineally-transposed antropyloric segment in cadavers. METHODS: The antropyloric segment, along with its carefully dissected branch of the anterior vagus, was mobilized based on the left gastroepiploic pedicle in six fresh human cadavers. The antropyloric valve was then transposed in the perineum after the pudendal nerve branches had been dissected out, and an approximation of these two nerves was performed to ascertain the technical feasibility of their neural anastomosis. RESULTS: The anterior vagus innervating the antropylorus could be harvested in all cadavers below the hepatic division of the main vagus trunk. The inferior rectal nerve or its branches were found consistently around the 3 or the 9 o'clock position in the ischioanal fossa. An anatomical tension-free approximation of the anterior vagus branch (of the transposed antropyloric segment) to the inferior rectal nerve in the perineum was feasible in all the cadavers studied. CONCLUSION: An inferior rectal nerve anastomosis with the anterior vagal branch of the perineally-transposed antropyloric segment can be achieved anatomically. This preliminary step can be the basis for future animal studies and subsequent clinical application of the procedure for possible neural control of the transposed antropyloric segment in the perineum.

Physiological and Functional Evaluation of the Transposed Human Pylorus as a Distal Sphincter

BACKGROUND/AIMS: Studies evaluating the human pylorus as a sphincter are scanty and contradictory. Recently, we have shown technical feasibility of transposing the human pylorus for end-stage fecal incontinence. This unique cohort of patients provided us an opportunity to study the sphincter properties of the pylorus in its ectopic position. METHODS: Antro-pylorus transposition on end sigmoid colostomies (n = 3) and in the perineum (n = 15) was performed for various indications. Antro-pylorus was assessed functionally (digital examination, high resolution spatiotemporal manometry, barium retention studies and colonoscopy) and by imaging (doppler ultrasound, MRI and CT angiography) in its ectopic position. RESULTS: The median resting pressure of pylorus on colostomy was 30 mmHg (range 28-38). In benign group, median resting pressure in perineum was 12.5 mmHg (range 6-44) that increased to 21.5 mmHg (range 12-29) (P = 0.481) and 31 mmHg (range 16-77) (P = 0.034) on first and second follow-up, respectively. In malignant group, median post-operative pressures were 20 mmHg (range 14-36) and 21 mmHg (range 18-44) on first and second follow-up, respectively. A definite tone and gripping sensation were felt in all the patients on digital examination. On distal loopogram, performed through the diverting colostomies, barium was retained proximal to the neo-pyloric valve. Both perineal ultrasound and MRI showed viable transposed graft. CT angiography and color doppler studies confirmed vascular flow in the transposed position. CONCLUSIONS: The human pyloric valve can function as a tonic sphincter when removed from the gastroduodenal continuity.