Powering Implantable Telemetry Devices from Localized Magnetic Fields

McCormick, Daniel J.; Hu, Aiguo Patrick; Nielsen, Poul; Malpas, Simon C.; Budgett, David

doi:10.1109/iembs.2007.4352793

Cited by 22 publications

(12 citation statements)

References 9 publications

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“…Sampling protocols were defined by the total period of sampling duration (12,8,6, 4, 3, 2, 1, 0.2 h) and the number of "on periods" that these data were spread throughout the day (1-120/day). For example, 12 h of data can either be collected as a single 12-h recording period or spread throughout the day as 12 1-h recording periods (Fig.…”

Section: Methodsmentioning

confidence: 99%

“…While improving all the time, the power consumption of the high bandwidth transmitters required for high-frequency signals such as SNA exceeds the limits of current capacity of small batteries if recordings are to be made for significant periods (e.g., Ͼ 1 month). Other methods of supplying power, such as using wireless power (4,12) are being developed for use in rodents, such as the rat, but for a number of reasons their application to larger animals, such as the rabbit, is limited. Intermittent sampling, with the telemeter turned off between sample periods, is obviously one approach for spreading limited battery capacity over extended recording periods.…”

mentioning

confidence: 99%

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Sampling of cardiovascular data; how often and how much?

Guild

Barrett²,

McBryde³

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

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Long-term measurement of cardiovascular variables by telemetry in laboratory animals has become indispensable in recent years. However, limited battery life and management of large volumes of recorded data are major drawbacks. These limitations can often be overcome by intermittent sampling of data. The question is, how much data does one need to collect to accurately reflect the underlying average value? To investigate this, 24-h continuous recordings of rabbit heart rate, arterial pressure, and integrated renal sympathetic nerve activity (RSNA) were resampled using a variety of protocols that differed with respect to the number of individual sampling periods used and the total amount of time that was sampled. The absolute percentage errors of estimates of the daily mean, standard deviation, and interquartile range were calculated for each sampling protocol. A similar analysis was repeated using arterial pressure data from rats. The results show that the number of sampling periods spread throughout the day had more effect than the total amount of data recorded. For example, just 2 h of total sampling time spread over 12 evenly spaced 10-min periods gave estimates of the daily mean of blood pressure and heart rate with <1% error and RSNA with <3% error. We show that accurate estimates of the daily mean of arterial pressure, heart rate, and RSNA can all be made using scheduled recording, and we recommend recording a minimum of 2 h/day spread over a number of periods throughout the day.

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Sampling of cardiovascular data; how often and how much?

Guild

Barrett²,

McBryde³

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

show abstract

“…The chamber can use a single big coil, the size of the chamber, or an array of smaller coils [17], [19][20][21][22]. Using a chamber the bottom of which is tiled with smaller TX coils has proven much more efficient than one with a single big coil that encompasses the whole area [19][20][21][22]. In fact, arrays of coils can provide homogeneous magnetic flux density within the entire chamber area.…”

Section: Introductionmentioning

confidence: 99%

“…Power localization focuses the transmitted power at the location of the power RX coil, so no resource is wasted [19][20][21]. Different techniques have been used to avoid driving all coils of an array simultaneously [13], [20][21][22]. In [20], a magnetic sensor is used to detect the location of a small magnet embedded in the RX and to activate the subset of coils that encompass the RX using dedicated control circuitry.…”

Section: Introductionmentioning

confidence: 99%

Towards a wireless optical stimulation system for long term in-vivo experiments

Mirbozorgi

Ameli

Gosselin

2014

2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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This paper presents our recent progresses towards the development of a wirelessly powered head mountable optical stimulator for enabling long-term optogenetic experiments with small freely moving transgenic models. The proposed system includes a wireless power transmission chamber with uniform power distribution in 3D and a wireless head mountable optical stimulator prototype with power recovery. The wireless power link, which includes the inductive chamber and power recovery circuits, is robust against subject movements in all directions, and against angular misalignment. Such link provides uniform power distribution without the need for a closed-loop control system, and can localize the transmitted power towards the receiver, without using additional detection and control circuitry compared to other systems. Additionally, the chamber is equipped with a camera for capturing the animal motion and behavior after applying optical stimulation patterns. A low-power microcontroller unit is embedded with the stimulator prototype to generate arbitrary light stimulation patterns. Measurement results show that the inductive chamber can continuously deliver 70 mW to the stimulator prototype with a power efficiency of 59%.

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“…A group of researchers from New Zealand [44] proposed a 3 × 3 nonoverlapping coil array for this application with each coil tuned at a different frequency. While this design provided good coverage in the center of the coils, the power delivered to the Rx coil on the corners of each coil was ~20 times less than the center.…”

Section: Introductionmentioning

confidence: 99%

Geometrical Design of a Scalable Overlapping Planar Spiral Coil Array to Generate a Homogeneous Magnetic Field

Jow

Ghovanloo

2013

IEEE Trans. Magn.

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We present a design methodology for an overlapping hexagonal planar spiral coil (hex-PSC) array, optimized for creation of a homogenous magnetic field for wireless power transmission to randomly moving objects. The modular hex-PSC array has been implemented in the form of three parallel conductive layers, for which an iterative optimization procedure defines the PSC geometries. Since the overlapping hex-PSCs in different layers have different characteristics, the worst case coil-coupling condition should be designed to provide the maximum power transfer efficiency (PTE) in order to minimize the spatial received power fluctuations. In the worst case, the transmitter (Tx) hex-PSC is overlapped by six PSCs and surrounded by six other adjacent PSCs. Using a receiver (Rx) coil, 20 mm in radius, at the coupling distance of 78 mm and maximum lateral misalignment of 49.1 mm (1/√3 of the PSC radius) we can receive power at a PTE of 19.6% from the worst case PSC. Furthermore, we have studied the effects of Rx coil tilting and concluded that the PTE degrades significantly when θ > 60°. Solutions are: 1) activating two adjacent overlapping hex-PSCs simultaneously with out-of-phase excitations to create horizontal magnetic flux and 2) inclusion of a small energy storage element in the Rx module to maintain power in the worst case scenarios. In order to verify the proposed design methodology, we have developed the EnerCage system, which aims to power up biological instruments attached to or implanted in freely behaving small animal subjects’ bodies in long-term electrophysiology experiments within large experimental arenas.

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Powering Implantable Telemetry Devices from Localized Magnetic Fields

Cited by 22 publications

References 9 publications

Sampling of cardiovascular data; how often and how much?

Sampling of cardiovascular data; how often and how much?

Towards a wireless optical stimulation system for long term in-vivo experiments

Geometrical Design of a Scalable Overlapping Planar Spiral Coil Array to Generate a Homogeneous Magnetic Field

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