Monitoring muscle activity in pediatric SCI: Insights from sensorized rocking chairs and machine-learning.

Activity-based therapy is effective at improving trunk control in children with spinal cord injury. A prototype sensorized rocking chair was developed and confirmed as an activity that activates trunk muscles. This study uses data collected from the chair to predict muscle use during rocking.

Development of a rocking chair for use by children with spinal cord injuries.

Purpose: Activity-based locomotor training improves intrinsic trunk control in children with spinal cord injury (SCI). To reinforce these improvements, there is a need to develop community integration activities to allow a patient to apply the retrained nervous system at home. One activity that has been explored is rocking in a rocking chair.

A Flow Sensor-Based Suction-Index Control Strategy for Rotary Left Ventricular Assist Devices.

Rotary left ventricular assist devices (LVAD) have emerged as a long-term treatment option for patients with advanced heart failure. LVADs need to maintain sufficient physiological perfusion while avoiding left ventricular myocardial damage due to suction at the LVAD inlet. To achieve these objectives, a control algorithm that utilizes a calculated suction index from measured pump flow (SIMPF) is proposed.

Design and Computational Evaluation of a Pediatric MagLev Rotary Blood Pump.

Pediatric heart failure (HF) patients have been a historically underserved population for mechanical circulatory support (MCS) therapy. To address this clinical need, we are developing a low cost, universal magnetically levitated extracorporeal system with interchangeable pump heads for pediatric support. Two impeller and pump designs (pump V1 and V2) for the pediatric pump were developed using dimensional analysis techniques and classic pump theory based on defined performance criteria (generated flow, pressure, and impeller diameter).

Photobleaching reduction in modulated super-resolution microscopy.

Important breakthroughs in far-field imaging techniques have been made since the first demonstrations of stimulated emission depletion (STED) microscopy. To date, the most straightforward and widespread deployment of STED microscopy has used continuous wave (CW) laser beams for both the excitation and depletion of fluorescence emission. A major drawback of the CW STED imaging technique has been photobleaching effects due to the high optical power needed in the depletion beam to reach sub-diffraction resolution.

Electroactive Interface for Enabling Spectroelectrochemical Investigations in Evanescent-Wave Cavity-Ring-Down Spectroscopy.

In this study, we report the development of an electrically active solid-liquid interface for the evanescent-wave cavity-ring-down spectroscopic (EW-CRDS) technique to enable spectroelectrochemical investigations of redox events. Because of a high-quality transparent conductive electrode film of indium tin oxide (ITO) coated on the interface of total internal reflection of the EW-CRDS platform, a cavity ring-down time of about 900 ns was obtained allowing spectroelectrochemical studies at solid-liquid interfaces. As a proof-of-concept on the capabilities of the developed platform, measurements were performed to address the effects of an applied electric potential to the adsorption behavior of the redox protein cytochrome c (Cyt-C) onto different interfaces, namely, bare-ITO, 3-aminopropyl triethoxysilane (APTES), and Cyt-C antibody.

Observation and modeling of conformational molecular structures driving the self-assembly of tri-adamantyl benzene on Ag(111).

The self-organization of tri-adamantyl (TAB) benzene molecules has been investigated using low temperature scanning tunneling microscopy (LT-STM). The molecular structures have also been studied using molecular modeling. In particular, these calculations have been performed on large areas (1000 nm(2)) from the atomic structure of the molecular building block, combining molecular dynamics (MD) and Monte-Carlo (MC) approaches.

Electrochemical dissolved oxygen removal from microfluidic streams for LOC sample pretreatment.

Current water quality monitoring for heavy metal contaminants largely results in analytical snapshots at a particular time and place. Therefore, we have been interested in miniaturized and inexpensive sensors suitable for long-term, real-time monitoring of the drinking water distribution grid, industrial wastewater effluents, and even rivers and lakes. Among the biggest challenges for such sensors are the issues of in-field device calibration and sample pretreatment.

Predicting supramolecular self-assembly on reconstructed metal surfaces.

The prediction of supramolecular self-assembly onto solid surfaces is still challenging in many situations of interest for nanoscience. In particular, no previous simulation approach has been capable to simulate large self-assembly patterns of organic molecules over reconstructed surfaces (which have periodicities over large distances) due to the large number of surface atoms and adsorbing molecules involved. Using a novel simulation technique, we report here large scale simulations of the self-assembly patterns of an organic molecule (DIP) over different reconstructions of the Au(111) surface.

Electrochemical and microfabrication strategies for remotely operated smart chemical sensors: application of anodic stripping coulometry to calibration-free measurements of copper and mercury.

Remote unattended sensor networks are increasingly sought after to monitor the drinking water distribution grid, industrial wastewater effluents, and even rivers and lakes. One of the biggest challenges for application of such sensors is the issue of in-field device calibration. With this challenge in mind, we report here the use of anodic stripping coulometry (ASC) as the basis of a calibration-free micro-fabricated electrochemical sensor (CF-MES) for heavy metal determinations.

Cardiac cell culture model as a left ventricle mimic for cardiac tissue generation.

A major challenge in cardiac tissue engineering is the delivery of hemodynamic mechanical cues that play a critical role in the early development and maturation of cardiomyocytes. Generation of functional cardiac tissue capable of replacing or augmenting cardiac function therefore requires physiologically relevant environments that can deliver complex mechanical cues for cardiomyocyte functional maturation. The goal of this work is the development and validation of a cardiac cell culture model (CCCM) microenvironment that accurately mimics pressure-volume changes seen in the left ventricle and to use this system to achieve cardiac cell maturation under conditions where mechanical loads such as pressure and stretch are gradually increased from the unloaded state to conditions seen in vivo.

Modeling the Self-Assembly of Nano Objects: Applications to Supramolecular Organic Monolayers Adsorbed on Metal Surfaces.

We present here the implementation of a code developed for the simulation of the self-assembly of nano objects (SANO). The code has the ability to predict the molecular self-assembly of different structural motifs by tuning the molecular building blocks as well as the metallic substrate. It consists in a two-dimensional grand canonical Monte Carlo (GCMC) approach developed to perform atomistic simulations of thousands of large organic molecules self-assembling on metal surfaces.

Endothelial cell culture model for replication of physiological profiles of pressure, flow, stretch, and shear stress in vitro.

The phenotype and function of vascular cells in vivo are influenced by complex mechanical signals generated by pulsatile hemodynamic loading. Physiologically relevant in vitro studies of vascular cells therefore require realistic environments where in vivo mechanical loading conditions can be accurately reproduced. To accomplish a realistic in vivo-like loading environment, we designed and fabricated an Endothelial Cell Culture Model (ECCM) to generate physiological pressure, stretch, and shear stress profiles associated with normal and pathological cardiac flow states.

Adsorptive behavior of CO2, CH4 and their mixtures in carbon nanospace: a molecular simulation study.

Using molecular simulation, four types of nanoporous carbons are examined as adsorbents for the separation of CO(2)/CH(4) mixtures at ambient temperature and pressures up to 10 MPa. First, the adsorption selectivity of CO(2) is investigated in carbon slit pores and single-walled carbon nanotube bundles in order to find the optimal pore dimensions for CO(2) separation. Then, the adsorptive properties of the optimized slit pore and nanotube bundle are compared with two realistic nanoporous carbon models: a carbon replica of zeolite Y and an amorphous carbon.

Transition from single-file to Fickian diffusion for binary mixtures in single-walled carbon nanotubes.

The transition from single-file diffusion to Fickian diffusion in narrow cylindrical pores is investigated for systems of rigid single-walled armchair carbon nanotubes, solvated with binary mixtures of Lennard-Jones fluids (Ar/Ne, Ar/Kr, and Ar/Xe). A range of effects is examined including the mixture concentration, the size ratio of the two components, and the nanotube diameter. The transition from single-file to Fickian diffusion in varying carbon nanotube diameters is analyzed in terms of the Fickian self-diffusivity and the single-file mobility of the mixture components.

Dual diffusion mechanism of argon confined in single-walled carbon nanotube bundles.

The adsorption and diffusion mechanisms of argon at 120 K were examined in a (25,0) single-walled carbon nanotube (SWCNT) bundle using a combination of Grand Canonical Monte Carlo and microcanonical molecular dynamics simulations. Interstices between the SWCNTs provided the most energetically favorable adsorption sites and filled completely at low relative pressure, followed by adsorption in the SWCNTs. We calculated the self-diffusivities from the average mean squared displacements of argon molecules.

Fully integrated three-dimensional electrodes for electrochemical detection in microchips: fabrication, characterization, and applications.

A scalable and rather inexpensive solution to producing microanalytical systems with "on-chip" three-dimensional (3D) microelectrodes is presented in this study, along with applicability to practical electrochemical (EC) detection scenarios such as preconcentration and interferant removal. This technique to create high-aspect-ratio (as much as 4:1) gold microstructures in constrained areas involved the modification of stud bump geometry with microfabricated silicon molds via an optimized combination of temperature, pressure, and time. The microelectrodes that resulted consisted of an array of square pillars approximately 18 microm tall and 20 microm wide on each side, placed at the end of a microfabricated electrophoresis channel.

Fabrication of a glass capillary electrophoresis microchip with integrated electrodes.

In this chapter, a detailed outline delineating the processing steps for microfabricating capillary electrophoresis (CE) with integrated electrochemical detection (ECD) platforms for performing analyte separation and detection is presented to enable persons familiar with microfabrication to enter a cleanroom and fabricate a fully functional Lab-on-a-Chip (LOC) microdevice. The processing steps outlined are appropriate for the production of LOC prototypes using easily obtained glass substrates and common microfabrication techniques. Microfabrication provides a major advantage over existing macro-scale systems by enabling precise control over electrode placement, and integration of all required CE and ECD electrodes directly onto a single substrate with a small footprint.

Portable high-voltage power supply and electrochemical detection circuits for microchip capillary electrophoresis.

Miniaturized, battery-powered, high-voltage power supply, electrochemical (EC) detection, and interface circuits designed for microchip capillary electrophoresis (CE) are described. The dual source CE power supply provides +/- 1 kVDC at 380 microA and can operate continuously for 15 h without recharging. The amperometric EC detection circuit provides electrode potentials of +/-2 VDC and gains of 1, 10, and 100 nA/V.

Fully integrated on-chip electrochemical detection for capillary electrophoresis in a microfabricated device.

Microfabricated lab-on-a-chip devices employing a fully integrated electrochemical (EC) detection system have been developed and evaluated. Both capillary electrophoresis (CE) channels and all CE/EC electrodes were incorporated directly onto glass substrates via traditional microfabrication techniques, including photolithographic patterning, wet chemical etching, DC sputtering, and thermal wafer bonding. Unlike analogous CE/EC devices previously reported, no external electrodes were required, and critical electrode characteristics, including size, shape, and placement on the microchip, were established absolutely by the photolithography process.