@conference {131,
	title = {Towards addressable wireless microstimulators based on electronic rectification of epidermically applied currents},
	booktitle = {Annual International Conference of the IEEE Engineering in Medicine and Biology Society},
	year = {2014},
	month = {2014///},
	pages = {3973 - 3976},
	publisher = {IEEE},
	organization = {IEEE},
	address = {Chicago},
	abstract = {<p>Electrical stimulation has been explored to restore the capabilities of the nervous system in paralysis patients. This area of research and of clinical practice, known as Functional Electrical Stimulation, would greatly benefit from further miniaturization of implantable stimulators. To that end, we recently proposed and demonstrated an innovative electrical stimulation method in which implanted microstimulators operate as rectifiers of bursts of innocuous high frequency current supplied by skin electrodes, thus generating low frequency currents capable of stimulating excitable tissues. A diode could suffice in some applications but, in order to broaden the method{\textquoteright}s clinical applicability, we envision rectifiers with advanced capabilities such as current control and addressability. We plan flexible thread-like implants (diameters \&lt; 300 urn) containing ASICs. As an intermediate stage, we are developing macroscopic implants (diameters \~{} 2 mm) made of off-the-shelf components. Here we present a circuit which responds to commands modulated within the high frequency bursts and which is able to deliver charge-balanced currents. We show that a number of these circuits can perform independent stimulation of segments of an anesthetized earthworm following commands from a computer.</p>
},
	keywords = {Batteries, Capacitors, Electrical Stimulation, Electrodes, Implants, Microcontrollers, Rectifiers},
	author = {Laura Becerra-Fajardo and Antoni Ivorra}
}
@conference {Ivorra2012,
	title = {{Injectable Rectifiers as Microdevices for Remote Electrical Stimulation: an Alternative to Inductive Coupling}},
	booktitle = {World Congress 2012 on Medical Physics and Biomedical Engineering},
	year = {2012},
	pages = {1581{\textendash}1584},
	address = {Beijing, China},
	abstract = {<p>Miniaturization of implantable medical electronic devices is currently compromised by the available means for electrically powering them. Most common energy supply techniques for implants {\textendash} batteries and inductive couplers {\textendash} comprise bulky parts which, in most cases, are significantly larger than the circuitry they feed. For overcoming such miniaturization bottleneck in the case of implants for electrical stimulation, we recently proposed and demonstrated a method based on making the implants operate as rectifiers of bursts of high frequency current supplied by remote electrodes. In this way, low frequency current is generated locally around the implant and this low frequency current performs stimulation of excitable tissues whereas the high frequency current only causes innocuous heating. The present paper reports further progress in this technology. We first describe construction and functional test of an injectable stimulator consisting of a single miniature diode (300 m {\texttimes} 300 m {\texttimes} 600 m) and two thin electrodes which is implanted trough a 19G needle into an anesthetized earthworm. We then propose a circuit architecture for implementing smart implants based on this technology. Both accomplishments are steps towards the implementation of injectable addressable microsystems for neuroprosthetics. These systems based on the proposed technology will look like short pieces of flexible thread rather than rigid capsules, as it was the case of previous miniature electrical stimulation implants. With currently available microelectronic techniques, very thin stimulation implants (diameter \&lt; 200 m) are easily conceivable. This technology may be foundational to a broad range of new developments in the field of implantable medical devices with applications ranging from wound healing to nerve stimulation for pain relief. In addition, other non-medical devices could also emerge such as implantable identification devices.</p>
},
	keywords = {Electrical Stimulation, Implantable Devices, Microsystems, Neuroprosthetics, Rectifiers},
	author = {Antoni Ivorra and Sacrist{\'a}n, J. and Baldi, A.}
}
