Gusphyl A. Justin

Passing data and supplying power to neural implants

This work investigates two important components in neural implants, the information link and the energy source. In this paper, a new concept in which neural implants operate on the biological resources readily available to them is adopted. The volume conduction property of human tissue is employed to pass information, and the electrons released during cellular metabolic process are collected to supply power. The x-antenna has been developed for data communication wherein the volume conduction mechanism has been used. The paper has shown that the bodys own energy stores can be converted to electrical current using a biofuel cell. The biofuel cell approach would provide not only uninterrupted power but also an opportunity to explore new methods fostering improved biocompatibility for implantable devices

Biofuel cells as a possible power source for implantable electronic devices

Biofuel cells were designed to investigate electricity production from Escherichia coli and human white blood cells as a preliminary investigation into the possible future use of such fuel cells as power sources for implantable electronic devices. The biofuel cells function is based on the coupling of glucose oxidation to the reduction of oxygen to water. It might, therefore, be possible to utilize the cellular processes involved in oxidative metabolism to generate electrical energy for numerous medical applications. In the bacteria experiment, we were able to generate small electrical currents, which gradually decreased over a (2) hour measurement period. In the human white blood cell experiment, our biofuel cell attained current outputs, which were smaller in magnitude than values recorded from the microbial biofuel cell.

Biofuel cells: a possible power source for implantable electronic devices

A biofuel cell was designed to investigate electricity production from Escherichia coli (E. Coli) and as a preliminary investigation into the possible future use of biofuel cells as power sources for implantable electronic devices. A plexiglass container was fabricated to house the biofuel cell components. Current densities of 24.9 /spl mu/Acm/sup -2/ were obtained, which decreased to 3.58 /spl mu/Acm/sup -2/ over a two hour period.

A Metabolic Biofuel Cell: Conversion of Human Leukocyte Metabolic Activity to Electrical Currents

An investigation of the electrochemical activity of human white blood cells (WBC) for biofuel cell (BFC) applications is described. WBCs isolated from whole human blood were suspended in PBS and introduced into the anode compartment of a proton exchange membrane (PEM) fuel cell. The cathode compartment contained a 50 mM potassium ferricyanide solution. Average current densities between 0.9 and 1.6 μA cm-2 and open circuit potentials (Voc) between 83 and 102 mV were obtained, which were both higher than control values. Cyclic voltammetry was used to investigate the electrochemical activity of the activated WBCs in an attempt to elucidate the mechanism of electron transfer between the cells and electrode. Voltammograms were obtained for the WBCs, including peripheral blood mononuclear cells (PBMCs - a lymphocyte-monocyte mixture isolated on a Ficoll gradient), a B lymphoblastoid cell line (BLCL), and two leukemia cell lines, namely K562 and Jurkat. An oxidation peak at about 363 mV vs. SCE for the PMA (phorbol ester) activated primary cells, with a notable absence of a reduction peak was observed. Oxidation peaks were not observed for the BLCL, K562 or Jurkat cell lines. HPLC confirmed the release of serotonin (5-HT) from the PMA activated primary cells. It is believed that serotonin, among other biochemical species released by the activated cells, contributes to the observed BFC currents.

An investigation of the ability of white blood cells to generate electricity in biofuel cells

The issue of energy supply is a significant challenge that currently inhibits the development of numerous implantable medical and therapeutic devices. Biofuel cell (BFC) technology may present a solution in this regard. BFCs are capable of generating electricity through the coupling of glucose oxidation to the reduction of molecular oxygen to water. Both glucose and oxygen are abundantly present within the cells of most biological organisms. In this study, we investigate whether it is possible to use human white blood cells (WBC) as microscopic bioreactors for glucose metabolism in a BFC. The presence of an electron transport chain (the enzyme complex NADPH oxidase) bound to the plasma membrane of phagocytic WBCs might provide an explanation for the currents that we observed when such cells were incorporated into a BFC setup.

A 128-Electrode Three Dimensional Electrical Impedance Tomography System

Electrical impedance tomography (EIT) is a new functional imaging technique. This paper presents the development of a new electrical impedance tomography system with 128 electrodes for impedance change detection and 3D imaging of the human thorax. The system consists of several modules, including multi-frequency current source, driving, measuring, data acquisition, and controlling and signal processing modules. A high speed digital signal processor (DSP) is used as the controller. The 64 driving electrodes and 64 measuring electrodes are positioned uniformly in four planes around the surface of a cylindrical phantom filled with a saline solution and objects of varying conductivities. The performance has been tested, and these preliminary experiments demonstrate the feasibility this system.

Serotonin (5-HT) released by activated white blood cells in a biological fuel cell provide a potential energy source for electricity generation

Previous studies by our group have demonstrated the ability of white blood cells to generate small electrical currents, on the order of 1-3 muA/cm2, when placed at the anode compartment of a proton exchange membrane (PEM) biological fuel cell. In this research study, an electrochemical technique is used to further investigate the electron transfer ability of activated white blood cells at interfacing electrodes in an attempt to elucidate the mechanism of electron transfer in the original biological fuel cell experiments. Cyclic voltammograms were obtained for human white blood cells using a three-electrode system. The working and counter electrodes were made from carbon felt and platinum, respectively, while the reference was a saturated calomel electrode (SCE). Oxidation peaks were observed at an average potential of 363 mV vs. SCE for the PMA/ionomycin activated white blood cells in glucose solution. However a corresponding reduction peak was not observed, suggesting irreversibility of the redox reaction. The cyclic voltammograms recorded for the white blood cells bear very close similarities to those of the neurotransmitter serotonin (5-HT). Serotonin released by white blood cells into the extracellular environment may be irreversibly oxidized at the working electrode in the cyclic voltammetry experiments and at the PEM biological fuel cell anode in our earlier electrochemical cell studies

A theoretical computation of abnormal oscillation propagation in a 2-D excitable neuronal network coupled via gap junction

The propagation of abnormal oscillations in actual neural tissue is often irregular and highly complex. The experiments and theoretical work on it are both very difficult; however, it can be helpful to understand some disorder in the neural system. With the help of microelectrode recording techniques and microdialysis, some experimental results from human beings and animal models have demonstrated that epileptic seizures can occur when either the external cellular environment of neurons is changed drastically from physiological conditions or when the synapses of neurons are extensively induced to release neurotransmitter or other neural signals. Here, we present a theoretical framework to investigate the gap junctions (electrical synapse) effect on the propagation of abnormal oscillations. Although such theoretical work is still very limited in explaining all the mechanistic problems related to the disorder situation, e.g., epilepsy, it is, nevertheless, helpful to our understanding of synaptic effects on the abnormal activity propagation. Now, from ionic channels to neural networks, a two-dimensional (2-D) spatial-temporal partial differential equation (PDE) is built. The implicit scheme of the finite-differential method in the time domain and a multistep algorithm are utilized to solve the PDE and the nonlinear ordinary differential equations, respectively, while the successive overrelaxation method is utilized to compute the large-scale sparse equations. Lyapunov exponent and approximate entropy are further applied, respectively, to the analysis of chaos and complexity in the propagation. Numerical results show that abnormal oscillations can propagate when the coupling strength of the gap junctions is sufficiently large, leading to turbulence in the excitable network, and that the larger the coupling strength is, the greater the nonlinear and the complexity of the propagation are. It is also concluded that the chaos and the complexity of the activity at the periphery point are larger than that at the central point when the abnormal oscillations propagate from the central to the periphery. This theoretical work is helpful to understand the gap junctions effects on the abnormal oscillation propagation in a 2-D excitable neural tissue.

On-demand controlled release of anti-inflammatory and analgesic drugs from conducting polymer films to aid in wound healing

An electronically-controlled drug delivery system (eDDS) for the on-demand release of anti-inflammatory, anti-microbial and analgesic agents to aid in wound healing is currently under development. The loading of several drugs into conductive polymer films and their subsequent on-demand, controlled release upon application of an electrical potential to the polymer film has been demonstrated. The loading and release (active and passive) of Ibuprofen sodium salt - a negatively charged analgesic and anti-inflammatory agent - from polypyrrole films is described. Major challenges identified include precise control over drug loading and passive release from the conducting polymers in the absence of an applied potential.

Synthesizing multi-view video frames for coding patient monitoring video.

This paper presents a method to synthesize multi-view video frames to facilitate coding and transmission of patient monitoring video. The synthesis is carried out in the DCT domain by means of interlacing. The synthesized video provides a higher video coding efficiency, better synchronization of the video streams from multiple cameras, as well as the improved data loss resilience and protection of the video content. The viability of the presented method was demonstrated by experimental results on patient monitoring video