Wireless Power Transfer and Optogenetic Stimulation of Freely Moving Rodents
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1
Erasmus Medical Center, Neuroscience, Netherlands
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2
Delft University of Technology, Bioelectronics, Netherlands
Animal studies are commonly used to test the feasibility and effectiveness of promising novel neuroscience research ideas. One such new technique is optogenetic stimulation, a state-of-the-art brain stimulation technique. In optogenetics, genetic techniques are used to create light-sensitive proteins within the neuron membrane, thus allowing the affected region to become sensitive to light stimulation, for example through an inserted LED. Current optogenetic stimulation methods use tethered setups and, typically, the animal-under-study is put into a fixed position. This introduces stress, which, besides an obvious reduction in animal welfare, may also influence the experimental results. Hence, an untethered setup is highly desirable. Therefore, in this study, we propose a wireless optogenetic stimulation setup, which allows for full freedom of movement of multiple rodents-under-study in a 40 cm x 40 cm x 20 cm environment.
We investigate a variety of wireless power transfer methods, which results in the choice for wireless power transfer through inductive coupling, as this allows for efficient power transfer over short range and has the least side-effects, making it the most suitable approach for this particular environment. The efficiency of inductive coupling is highly susceptible to vertical, lateral and angular misalignment of the coils. The wireless link is, therefore, designed to maximize the link efficiency and minimize the misalignments between the coils. In order to maximize the inductive power transfer link, we look into
all the aspects that have an influence on the link efficiency, including coil shape and coil material. The implementation of the wireless optogenetics setup is divided into three parts:
Transmitter Coil: The design of a transmitter coil capable of providing sufficient link efficiency throughout the entire 40 cm x 40 cm x 20 cm region of interest, in order to be able to power the optogenetic stimulation receiver, regardless of lateral and vertical misalignments.
Receiver Module: The design of a receiver module that resides on the animal and, as such, is severely restricted in both size and weight. The complete module with receiver coil, rectifying and regulating electronics and microcontroller can occupy at most 1 cm x 1 cm x 1 cm and weights below 1 g. Moreover, half of allowable volume of the receiver module is kept unused for the future assembly including the wireless ECoG recording electronics.
Optogenetics Optrodes: The creation of optogenetics optrodes using a novel micro-LED mounting technique, which allows for the micro-LED array with multiple micro-LEDs to be directly inserted into the brain. The use of a micro-LED array greatly improves the power efficiency, as the traditional LED-to-optical-fiber coupling is accompanied by large losses in light-intensity. Moreover, a single optrode is able to replace a number of optical fibers, resulting in a less-invasive procedure if multiple stimulation sites are required.
For an input current of 0.5 A into the primary coil, an average inductive link efficiency of 0.28 %, and an angular misalignment of 45 degrees, the final setup is capable of delivering at least 8.5 mW of light power into the brain.
Keywords:
Brain Stimulation,
Epilepsy,
inductive coupling,
optogenetics,
Optrodes,
Wireless power transfer
Conference:
The Cerebellum inside out: cells, circuits and functions
, ERICE (Trapani), Italy, 1 Dec - 5 Dec, 2016.
Presentation Type:
poster
Topic:
Cellular & Molecular Neuroscience
Citation:
Nassirinia
F,
Hoebeek
FE and
Serdijn
WA
(2019). Wireless Power Transfer and Optogenetic Stimulation of Freely Moving Rodents.
Conference Abstract:
The Cerebellum inside out: cells, circuits and functions
.
doi: 10.3389/conf.fncel.2017.37.00003
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Received:
29 Nov 2016;
Published Online:
25 Jan 2019.
*
Correspondence:
Ms. Farnaz Nassirinia, Erasmus Medical Center, Neuroscience, Rotterdam, Netherlands, farnaznn@gmail.com