Implantable Neurostimulators ; Micro-Electrical-Mechanical Systems ; Microelectrodes

The paper proposed a new method to design and fabricate a flexible neural microelectrode arrays (MEA) for retinal prosthesis, the ion-beam technology was introduced to decrease the width of conductive wires and the distances between wires, a high density MEA (120 microelectrodes with a matrix of 10 x 12) was fabricated on a single layer of polymer from this. The MEA was proved to possess a fine electrochemical property. In vitro test, the average impedance of MEA on 1 kHz was 16 k omega +/- 2 k omega and the average phase difference was -85 degrees +/-30 degrees.
Micro-Electrical-Mechanical Systems ; Microelectrodes ; Prosthesis Design ; Visual Prosthesis

Objective To investigate the electrophysiological and morphological properties of the single ventral neuron in the medial geniculate body (MGBv) in rats. Methods The basic electrophysiological properties and action potentials at different levels of membrane potentials were recorded by whole cell patch clamp technique. Morphological properties of ventral neurons in the medial geniculate body were studied by biocytin staining. Results Nissl and biocytin stainings indicated that MGBv neurons were composed of oval shaped cell bodies, and the dendritic branches were tufted. In current clamp recordings, the resting membrane potential was (-54.92?10.85) mV, the input resistance (945.67?507.80) M?, the membrane capacitance (5.37?1.98) pF, and the time constant (2 109 87 ?2 496 01) ?s. Action potentials under different current inputs were various. Spontaneous discharge could be recorded by voltage clamp and current clamp. Conclusion MGBv dendritic trees are fairly dense with bushy tufted neurons and variety of action potentials under different current inputs in ventral neurons of the medial geniculate body. Spontaneous activities recorded by current clamp are similar to the action potential, which may be the spontaneous action potential due to the exceeding of membrane potential over liminal value.

Objective To improve the set up accuracy for patients by MED TEC thermoplastic sheet. Methods First, a reference positioning line was scored on the supporting board of MEC TEC. Then, lines on the patient body were marked according to the reference positioning line. After fastening MED TEC thermoplastic sheet, CT top view imagines of patients who were immobilized with MED TEC thermoplastics sheet on the CT scanner were then drawn. The results by PC graphics software were analysed. Results A total of 57 cases was studied. Deviation in 52 (91.2%) cases was less than 3?mm. The cause of the with deviation exceeding 5?mm were all found.Conclusion Using the right method is very important. Thus, results with satisfactory deviations could be obtained when the set up are repeated.

Objective To establish a whole-body dynamic inhalation exposure system for toxicological studies on highly toxic chemicals, and to evaluate the safety and applicability of the system.Methods The safety and standardization of the laboratory were ensured after positive and negative pressure protection and airtight protection were finished.By modifying and optimizing the key technological units of the exposure chamber, the relationships between aerosol concentrations in the chamber and the push rate, exposure time and different monitoring points were investigated.Results and Conclusion Multi-protection was achieved, including the independent exposure chamber, negative pressure experiment and positive pressure protection under working conditions.The laboratory meets the demands of safety and specifications.The exposure aerosol concentrations in the chamber are uniform, stable and controllable while the air is dynamically flowing.The whole-body dynamic inhalation exposure system can meet the need for toxicological studies on highly toxic chemicals.

Three-electrode testing method was used to investigate the effect of temperature on electrode impedance, and the pH shifts in saline solution resulting from the electrical stimulation were also determined. Experiments in PBS (phosphate buffered solution) solution showed that the electrode impedance was almost invariable at the human body temperature range (35 degrees C-40 degrees C). And the experiments in unbuffered saline solution showed that pH shifts decreased from 0.03 to 0.005 when the frequency of biphasic charged-balanced pulses increased from 1 Hz to 100 Hz. Even stimulated by monophasic pulses (frequency is 15 Hz, amplitude is 50 microA), the stimulus-induced pH shift of electrode only varies 0.15 (anodic pulse current increased 0.15 and cathodic pulse current decreased 0.15).
Electrochemistry ; Eye, Artificial ; Materials Testing ; Microelectrodes ; Prostheses and Implants

This paper proposed a new design on multi-layer flexible microelectrode arrays (MEA) of epiretinal prosthesis, as well as a set of automatic testing system to evaluate and analyze the MEA. Experiment results showed that the MEA was satisfying on both flexibility and impedance and the multi-layer design didn't introduce significant differences.
Microarray Analysis ; Microelectrodes ; Prostheses and Implants ; Prosthesis Design ; Prosthesis Implantation ; instrumentation ; Retina

This review paper presents the current research progress, challenges and future development on microelectrode array of retinal prosthesis, including epi-retinal and sub-retinal implants.
Microelectrodes ; Prosthesis Design ; Visual Prosthesis