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In Vivo Demonstration of Addressable Microstimulators Powered by Rectification of Epidermically Applied Currents for Miniaturized Neuroprostheses.

Becerra-Fajardo L, Ivorra A - PLoS ONE (2015)

Bottom Line: This approach has the potential to result in an unprecedented level of miniaturization as no bulky parts such as coils or batteries are included in the implant.In addition, we numerically show that the high frequency current bursts comply with safety standards both in terms of tissue heating and unwanted electro-stimulation.We demonstrate that addressable microstimulators powered by rectification of epidermically applied currents are feasible.

View Article: PubMed Central - PubMed

Affiliation: Department of Information and Communication Technologies, Universitat Pompeu Fabra, Barcelona, Spain.

ABSTRACT
Electrical stimulation is used in order to restore nerve mediated functions in patients with neurological disorders, but its applicability is constrained by the invasiveness of the systems required to perform it. As an alternative to implantable systems consisting of central stimulation units wired to the stimulation electrodes, networks of wireless microstimulators have been devised for fine movement restoration. Miniaturization of these microstimulators is currently hampered by the available methods for powering them. Previously, we have proposed and demonstrated a heterodox electrical stimulation method based on electronic rectification of high frequency current bursts. These bursts can be delivered through textile electrodes on the skin. This approach has the potential to result in an unprecedented level of miniaturization as no bulky parts such as coils or batteries are included in the implant. We envision microstimulators designs based on application-specific integrated circuits (ASICs) that will be flexible, thread-like (diameters < 0.5 mm) and not only with controlled stimulation capabilities but also with sensing capabilities for artificial proprioception. We in vivo demonstrate that neuroprostheses composed of addressable microstimulators based on this electrical stimulation method are feasible and can perform controlled charge-balanced electrical stimulation of muscles. We developed miniature external circuit prototypes connected to two bipolar probes that were percutaneously implanted in agonist and antagonist muscles of the hindlimb of an anesthetized rabbit. The electronic implant architecture was able to decode commands that were amplitude modulated on the high frequency (1 MHz) auxiliary current bursts. The devices were capable of independently stimulating the target tissues, accomplishing controlled dorsiflexion and plantarflexion joint movements. In addition, we numerically show that the high frequency current bursts comply with safety standards both in terms of tissue heating and unwanted electro-stimulation. We demonstrate that addressable microstimulators powered by rectification of epidermically applied currents are feasible.

No MeSH data available.


Related in: MedlinePlus

Force modulation capabilities.Force exerted on the load cell by independently stimulating the tibialis anterior and the gastrocnemius muscles. The magnitude of the force was modulated by varying the frequency of the stimulation bursts.
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pone.0131666.g008: Force modulation capabilities.Force exerted on the load cell by independently stimulating the tibialis anterior and the gastrocnemius muscles. The magnitude of the force was modulated by varying the frequency of the stimulation bursts.

Mentions: Fig 8 shows two trials in which the frequency of the stimulation bursts (F) was increased from 40 Hz to 100 Hz while the features of the biphasic pulse were kept constant. It can be observed that the force exerted by the foot on the load cell increased with the frequency of the bursts. That is, force modulation was not only possible by varying the amplitude of the pulses or their duration (results not shown here) but also by varying the repetition rate of the stimulation bursts. This is a common observation in neuromuscular electrical stimulation when regular low frequency pulses are employed [30]. Therefore, this seems to indicate that the outcome of the currents generated by the devices (rectified HF current bursts) was equivalent to that of regular current pulses.


In Vivo Demonstration of Addressable Microstimulators Powered by Rectification of Epidermically Applied Currents for Miniaturized Neuroprostheses.

Becerra-Fajardo L, Ivorra A - PLoS ONE (2015)

Force modulation capabilities.Force exerted on the load cell by independently stimulating the tibialis anterior and the gastrocnemius muscles. The magnitude of the force was modulated by varying the frequency of the stimulation bursts.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493086&req=5

pone.0131666.g008: Force modulation capabilities.Force exerted on the load cell by independently stimulating the tibialis anterior and the gastrocnemius muscles. The magnitude of the force was modulated by varying the frequency of the stimulation bursts.
Mentions: Fig 8 shows two trials in which the frequency of the stimulation bursts (F) was increased from 40 Hz to 100 Hz while the features of the biphasic pulse were kept constant. It can be observed that the force exerted by the foot on the load cell increased with the frequency of the bursts. That is, force modulation was not only possible by varying the amplitude of the pulses or their duration (results not shown here) but also by varying the repetition rate of the stimulation bursts. This is a common observation in neuromuscular electrical stimulation when regular low frequency pulses are employed [30]. Therefore, this seems to indicate that the outcome of the currents generated by the devices (rectified HF current bursts) was equivalent to that of regular current pulses.

Bottom Line: This approach has the potential to result in an unprecedented level of miniaturization as no bulky parts such as coils or batteries are included in the implant.In addition, we numerically show that the high frequency current bursts comply with safety standards both in terms of tissue heating and unwanted electro-stimulation.We demonstrate that addressable microstimulators powered by rectification of epidermically applied currents are feasible.

View Article: PubMed Central - PubMed

Affiliation: Department of Information and Communication Technologies, Universitat Pompeu Fabra, Barcelona, Spain.

ABSTRACT
Electrical stimulation is used in order to restore nerve mediated functions in patients with neurological disorders, but its applicability is constrained by the invasiveness of the systems required to perform it. As an alternative to implantable systems consisting of central stimulation units wired to the stimulation electrodes, networks of wireless microstimulators have been devised for fine movement restoration. Miniaturization of these microstimulators is currently hampered by the available methods for powering them. Previously, we have proposed and demonstrated a heterodox electrical stimulation method based on electronic rectification of high frequency current bursts. These bursts can be delivered through textile electrodes on the skin. This approach has the potential to result in an unprecedented level of miniaturization as no bulky parts such as coils or batteries are included in the implant. We envision microstimulators designs based on application-specific integrated circuits (ASICs) that will be flexible, thread-like (diameters < 0.5 mm) and not only with controlled stimulation capabilities but also with sensing capabilities for artificial proprioception. We in vivo demonstrate that neuroprostheses composed of addressable microstimulators based on this electrical stimulation method are feasible and can perform controlled charge-balanced electrical stimulation of muscles. We developed miniature external circuit prototypes connected to two bipolar probes that were percutaneously implanted in agonist and antagonist muscles of the hindlimb of an anesthetized rabbit. The electronic implant architecture was able to decode commands that were amplitude modulated on the high frequency (1 MHz) auxiliary current bursts. The devices were capable of independently stimulating the target tissues, accomplishing controlled dorsiflexion and plantarflexion joint movements. In addition, we numerically show that the high frequency current bursts comply with safety standards both in terms of tissue heating and unwanted electro-stimulation. We demonstrate that addressable microstimulators powered by rectification of epidermically applied currents are feasible.

No MeSH data available.


Related in: MedlinePlus