A surface mountable glucose fuel cell for medical implants

We present an enzymeless, surface mountable glucose fuel cell based on abiotic catalysts. The device is intended as an energy harvesting implantable power supply for low power medical implants and sensors. After 50 days of operation in physiological glucose solution the fuel cell exhibited a stable performance of 1.1 muW/cm2. The demonstrated lifetime of our glucose fuel cell therefore already exceeds the maximum lifetime reported for devices based on enzymatic catalysts. This renders the concept a promising approach for the development of autonomous and sustainable power supply systems for long- term medical implants

Clinical Evaluation of a Telemedically Linked Intraoral Drug Delivery System

The miniaturized intraoral drug delivery system BuccalDose is composed of a replaceable cartridge which is worn in a removable prosthesis and an external base station for telemedical therapy monitoring. The system has now been tested for the first time with Parkinson\u2019s disease (PD) patients. The study evaluated the usability of the entire system, the functionality of the telemedical transmission path and the functionality of the cartridge, which uses an osmotic pumping principle to release a liquid drug formulation to the buccal mucosa. The BuccalDose system was generally considered to be easy to handle, even with movement disorders, up to a mild-moderate disease stage. In addition, the obtained in vivo release rates of the cartridges confirmed the previously achieved in vitro release behavior

Morphological evolution of electrochemically plated stripped lithium microstructures by synchrotron X ray phase contrast tomography

Due to its low redox potential and high theoretical specific capacity, Li metal has drawn worldwide research attention because of its potential use in next generation battery technologies such as Li S and Li O2. Unfortunately, uncontrollable growth of Li microstructures LmSs, e.g., dendrites, fibers during electrochemical Li stripping plating has prevented their practical commercialization. Despite various strategies proposed to mitigate LmS nucleation and or block its growth, a fundamental understanding of the underlying evolution mechanisms remains elusive. Herein, synchrotron in line phase contrast X ray tomography was employed to investigate the morphological evolution of electrochemically deposited dissolved LmSs nondestructively. We present a 3D characterization of electrochemically stripped Li electrodes with regard to electrochemically plated LmSs. We clarify fundamentally the origin of the porous lithium interface growing into Li electrodes. Moreover, cleavage of the separator caused by growing LmS was experimentally observed and visualized in 3D. Our systematic investigation provides fundamental insights into LmS evolution and enables us to understand the evolution mechanisms in Li electrodes more profoundl

Improving Effective Surgical Delivery in Humanitarian Disasters: Lessons from Haiti

Kathryn Chu and colleagues describe the experiences of Médecins sans Frontières after the 2010 Haiti earthquake, and discuss how to improve delivery of surgery in humanitarian disasters

An intra-cerebral drug delivery system for freely moving animals

Abstract Microinfusions of drugs directly into the central nervous system of awake animals represent a widely used means of unravelling brain functions related to behaviour. However, current approaches generally use tethered liquid infusion systems and a syringe pump to deliver drugs into the brain, which often interfere with behaviour. We address this shortfall with a miniaturised electronically-controlled drug delivery system (20×17.5×5 mm 3 ) designed to be skull-mounted in rats. The device features a micropump connected to two 8-mm-long silicon microprobes with a cross section of 250×250 μm 2 and integrated fluid microchannels. Using an external electronic control unit, the device allows infusion of 16 metered doses (0.25 μL each, 8 per silicon shaft). Each dosage requires 3.375 Ws of electrical power making the device additionally compatible with state-of-the-art wireless headstages. A dosage precision of 0.25±0.01 μL was determined in vitro before in vivo tests were carried out in awake rats. No passive leakage from the loaded devices into the brain could be detected using methylene blue dye. Finally, the device was used to investigate the effects of the NMDA-receptor antagonist 3-((R)-2-Carboxypiperazin-4-yl)-propyl-1-phosphonic acid, (R)-CPP, administered directly into the prefrontal cortex of rats during performance on a task to assess visual attention and impulsivity. In agreement with previous findings using conventional tethered infusion systems, acute (R)-CPP administration produced a marked increase in impulsivity

Static and Dynamic Behaviour of Gas Bubbles in T-Shaped Non-Clogging Micro-Channels

Abstract Preventing micro-channels from clogging is a major issue in most micro and nanofluidic systems (Gravesen et al., J Micromech Microeng 3(4):168-182, 1993; Jensen et al., In: Proc. of MicroTAS 2002, Nara, Japan, pp 733-735, 2002 Wong et al., J Fluid Mech 292:71-94, 1995). The T-shaped channel first reported by Kohnle et al. (In: IEEE MEMS, the 15th international IEEE micro electro mechanical conference (ed), Las Vegas, pp 77-80, 2002) prevents micro-channels from clogging by the aid of the equilibrium bubble position in such a geometry. This work is concerned with the static and dynamic behaviour of bubbles in such T-shaped microchannels. The aspect ratio of a rectangle enclosing the Tshaped channel and the contact angle of the walls are the main parameters influencing the static and dynamic bubble behaviour. It is investigated in this article how these parameters relate to the equilibrium bubble shape and how optimum bubble velocities can be achieved inside the channel. An analytical model depending on the contact angle and the channel geometry is presented that allows to determine the bubble configuration inside the channel by minimizing the bubble's surface energy. A second model is derived to predict the velocity of gas bubbles driven by buoyancy in vertical T-shaped channels. The model is applied to design T-shaped channels with a maximum mobility of gas bubbles. Experiments with MEMS fabricated devices and CFD simulations are used to verify the models. Furthermore design rules for an optimum nonclogging channel geometry which provides the highest gas bubble mobility are given

Process Development for a High-throughput Fine Line Metallization Approach Based on Dispensing Technology

AbstractIn order to enhance prosperous dispensing technology towards an industrial application, besides a continuous process development, especially throughput rate has to be increased. In this study, paste rheology of two different dispensing pastes was transferred to CFD-simulation (CFD: Computational Fluid Dynamics) to investigate different nozzle geometries and print head designs. In the following, a single nozzle dispensing setup was used to verify simulative values by comparing them with those obtained from experimental investigations. Consequently, the single nozzle process was scaled to a parallel application, where a homogeneous pressure and flow distribution within the print head turned out to be crucial to achieve a homogeneous mass flow at all nozzles. In various iteration steps, the influence of fabrication tolerances especially concerning the nozzle geometry was isolated and print head designs were optimized based on CFD towards maximum process stability. Based on these results, a novel 10 nozzle fine line dispensing unit was designed and fabricated. Finally, successful cell production with resulting finger widths of less than 35μm could be demonstrated using the novel prototype