Methods and systems for identifying a particle using dielectrophoresis

A system for identifying a particle. The system includes a microfluidic device; a microelectrode array including a plurality of electrodes, the microelectrode array disposed within the microfluidic device; a plurality of particles suspended in a solution and delivered to the microelectrode array using the microfluidic device; a signal generator operatively coupled to the microelectrode array; a particle detector adjacent to the microelectrode array; and a controller in operative communication with the signal generator and the particle detector. The controller is configured to apply an oscillating voltage signal to the microelectrode array between a low frequency and a high frequency at a sweep rate, wherein the sweep rate is no more than a maximum sweep rate, and determine a distribution of the plurality of particles relative to the microelectrode array at a plurality of frequency levels between the low frequency and the high frequency.https://digitalcommons.mtu.edu/patents/1139/thumbnail.jp

Wide field epiretinal micro-electrode-design and feature test

This study was aimed to design and fabricate a wide field implantable epi-retinal microelectrode array for the purpose of retinal repair, and to perform electrochemical test on the array. With parylene as flexible substrate material and Pt as electrode and route material, microelectrode array prototypes was designed and fabricated, and electric characteristics of the array was tested with the three-electrode test system. The feature analysis showed that morphological and electrical properties of the array well met the requirements of implantation and electrical stimulation of retina. The microelectrode array can be put in the in vivo electrophysiological experiments on animal and can perform reliably. © 2013 IEEE.published_or_final_versio

Microelectrode arrays and the use of PEG-functionalized diblock copolymer coatings

PEG-modified diblock copolymer surfaces have been examined for their compatibility with microelectrode array based analytical methods. The use of PEG-modified polymer surfaces on the arrays was initially problematic because the redox couples used in the experiments were adsorbed by the polymer. This led the current measured by cyclic voltammetry for the redox couple to be unstable and increase with time. However, two key findings allow the experiments to be successful. First, after multiple cyclic voltammograms the current associated with the redox couple does stabilize so that a good baseline current can be established. Second, the rate at which the current stabilizes is consistent every time a particular coated array is used. Hence, multiple analytical experiments can be conducted on an array coated with a PEG-modified diblock copolymer and the data obtained is comparable as long as the data for each experiment is collected at a consistent time point

Sonochemically fabricated microelectrode arrays for biosensors. Part II. Modification with a polysiloxane coating

A polymer modified sonochemically fabricated glucose oxidase microelectrode array with microelectrode population densities of up to 2.5 x 105 microelectrodes cm-2 is reported. These microelectrode sensors were formed by first depositing an insulating film on commercial screen printed electrodes which was subsequently sonicated to form cavities of regular sizes in the film. Electropolymerisation of aniline at the microelectrode cavities formed polyaniline protrusions containing entrapped glucose oxidase. Chemical deposition of polysiloxane from dichlorodimethysilane was used to deposit a thin protective and diffusion mass transport controlling coating over the electrodes. The physical and electrochemical properties of these films were studied. The performance of the final glucose oxidase based microelectrode sensor array is reported

Intraneural stimulation using 2D wire-microelectrode arrays: II. Comparison with single-wire electrode results

A two-dimensional wire-microelectrode array was inserted into the peroneal nerve of the rat through an incision. For each of the electrodes in the array the corresponding twitch-force recruitment curve was recorded from the extensor digitorum longus muscle (EDL). The mean value and standard deviation of the threshold current were found to be not significantly different from those for single wire electrodes. This suggests that the incision does not introduce significant (additional) current leakag

Intraneural stimulation using 2D wire-microelectrode arrays: I. Experimental results

A two-dimensional 24-channel wire-microelectrode array was inserted into the peroneal nerve of the rat during acute experiments. The electrodes in the array are on a regular grid of 6 by 4 electrodes; inter-electrode spacing is 120 ¿m. For each of the electrodes in the array the corresponding twitch-force recruitment curve was recorded from the extensor digitorum longus muscle (EDL). A complete set of 24 recruitment curves is presented The shape of the recruitment curves varies among the electrodes in the array. This supports previous findings which suggest a different motor unit recruitment order for stimulating electrodes at different intraneural position

Intraneural stimulation using wire-microelectrode arrays: analysis of force steps in recruitment curves

In acute experiments on six Wistar rats, a wire-microelectrode array was inserted into the common peroneal nerve. A 5-channel array and a 24-channel array were available. Each electrode in the array was used to generate a twitch contraction force recruitment curve for the extensor digitorum longus muscle. We constructed a histogram of the pooled force steps in all recruitment curves. From a comparison of this experimental histogram with one estimated from literature data, we found that the force steps encountered in our experiments are in the same range as those from the literature-based estimated distribution. Discrepancies between the experimental and the literature-based histogram might be ascribed to an approximation used in the estimated distribution. We conclude that force step histograms appear to provide a simple means for estimating motor unit twitch force distributions, and thus are of value in studies of intraneural selective stimulatio