Fully-Passive Wireless Implant for Neuropotential Acquisition: An <i>In Vivo</i> Validation

Moncion, Carolina; Balachandar, Lakshmini; Venkatakrishnan, Satheesh Bojja; Riera, Jorge J.; Volakis, John L.

doi:10.1109/jerm.2019.2895657

Cited by 15 publications

(14 citation statements)

References 16 publications

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“…When implantable neural sensors are placed under the skin, and interrogator is 2 mm away, the system loss is approximately 30 dB, deduced as the difference between the input neural power of -58 dBm and the received sideband power of -89 dBm, as illustrated in Fig. 6., which is similar to the values reported in [8].System Performance Analysis and Projection: The key performance metrics for a neural recording unit are a) low interrogating power, b) high backscattering power because of low conversion, propagation and other system losses and c) high sensitivity to weak (20 microvolts) neurosignals. These three aspects are examined in detail here with a simple diagram Fig.…”

Section: Resultssupporting

confidence: 80%

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Miniaturized Fully-Passive Wireless Neural Recording with Heterogeneous Integration in Thin Packages

Sayeed¹,

Pulugartha²

2022

Preprint

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Wireless fully-passive neural recording systems are demonstrated with heterogeneous integration of sensing, mixing and communication components in flexible polymer dielectric films. The recording neurosensor has an antenna, antiparallel diode, and a by-pass capacitor to modulate an incoming carrier signal with the neuropotentials and backscatter the mixed signal to an external reader circuit. Planar antennas are realized on Liquid Crystal Polymer (LCP) flexible substrates with low dielectric constant. The designed antenna topology is realized with a single metal layer and eliminates the dependency on substrate thickness and leads to thinner sensors. This is a major advance compared to prior passive neural recording with rigid and thicker substrates and components. Approximately 80% thickness reduction and 20% volume reduction are achieved with similar performance compared to earlier studies. Our approach thus leads to low-cost and disposable wireless neurosensors on a flexible platform with heterogenous integration.

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Section: Resultssupporting

confidence: 80%

“…The whole wireless neurosensor is designed to a size of 15 mm ×16mm ×1.5 mm. With further advances in design, the device is miniaturized to 10 mm × 9 mm × 2.2mm [7], [8]. Existing neupotential sensors are based on rigid or flexible PCB substrates.…”

Section: Introductionmentioning

confidence: 99%

Miniaturized Fully-Passive Wireless Neural Recording with Heterogeneous Integration in Thin Packages

Sayeed¹,

Pulugartha²

2022

Preprint

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“…34,35 Given the small area of S1HL, it is difficult to perform simultaneous wired and wireless recordings of SSEPs, and for this reason, the recordings were performed sequentially. 32 Three different RF power levels of 11, 9, and 7 dBm were used. Each of these recordings, along with the wired recording, had duration of approximately 10 min and was digitized at a 2 kHz sampling rate.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…We followed the previous method of SSEP signal processing. 32 The wired and wireless signals were first band-pass filtered from 4 to 80 Hz and then notch filtered between 35 and 45 Hz. The filtered signals were then segmented from −50 to 250 ms referenced to the onset of the recorded stimulation pulse.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…31 Another previous work reported in vivo validation of the fully passive wireless system using somatosensory evoked potentials (SSEPs). 32 This work was performed by wiring the electrode inside the scalp to the external wireless system. In this article, we evaluate the biocompatible and flexible recorder in a practical implanted environment, using both an invitro tissue-simulating phantom model and an in vivo epileptic rat model.…”

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confidence: 99%

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Fully Passive Flexible Wireless Neural Recorder for the Acquisition of Neuropotentials from a Rat Model

et al. 2019

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Wireless implantable neural interfaces can record high-resolution neuropotentials without constraining patient movement. Existing wireless systems often require intracranial wires to connect implanted electrodes to an external head stage or/and deploy an application-specific integrated circuit (ASIC), which is battery-powered or externally power-transferred, raising safety concerns such as infection, electronics failure, or heat-induced tissue damage. This work presents a biocompatible, flexible, implantable neural recorder capable of wireless acquisition of neuropotentials without wires, batteries, energy harvesting units, or active electronics. The recorder, fabricated on a thin polyimide substrate, features a small footprint of 9 mm × 8 mm × 0.3 mm and is composed of passive electronic components. The absence of active electronics on the device leads to near zero power consumption, inherently avoiding the catastrophic failure of active electronics. We performed both in vitro validation in a tissue-simulating phantom and in vivo validation in an epileptic rat. The fully passive wireless recorder was implanted under rat scalp to measure neuropotentials from its contact electrodes. The implanted wireless recorder demonstrated its capability to capture low voltage neuropotentials, including somatosensory evoked potentials (SSEPs), and interictal epileptiform discharges (IEDs). Wirelessly recorded SSEP and IED signals were directly compared to those from wired electrodes to demonstrate the efficacy of the wireless data. In addition, a convoluted neural network-based machine learning algorithm successfully achieved IED signal recognition accuracy as high as 100 and 91% in wired and wireless IED data, respectively. These results strongly support the fully passive wireless neural recorder's capability to measure neuropotentials as low as tens of microvolts. With further improvement, the recorder system presented in this work may find wide applications in future brain machine interface systems.

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Appendix A Antennas and Sensors for Medical Applications: A Representative Literature Review

Song¹,

Rahmat‐Samii²

2021

Antenna and Sensor Technologies in Modern Medical Applications

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Advanced wireless diagnosis and treatment technologies have recently and rapidly moved from largely a vision of science fiction to widely spreading consumer and clinical products. Large numbers of research and literature are published in different journals and conferences each year on the development of antennas and sensors of various health-care applications. This chapter presents a representative literature review on the recently developed antenna and sensor technologies for advanced medical applications. A block diagram summarizing the subtopics included in this review chapter is shown in Figure A.1. The antenna-related topics are broken into three subsections according to their operating mechanisms: medical imaging antennas and coils, wireless telemetry antennas for implantable and ingestible devices, and microwave ablation antennas for localized tumor treatments. The discussion on sensor technologies consists of mechanical, electrical, optical, and chemical sensing devices. For each of the subtopics, we present the basic system-level physics, followed by the state of the art with representative literature, general outlooks for current challenges, and potential solutions in each field. This review not only serves as an introductory platform for new researchers to the fields but also benefits experienced researchers by broadening their views among various related topics. Various chapters of this book provide in-depth discussions with additional references, detailing the topics briefly covered in this appendix.

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Fully-Passive Wireless Implant for Neuropotential Acquisition: An In Vivo Validation

Cited by 15 publications

References 16 publications

Miniaturized Fully-Passive Wireless Neural Recording with Heterogeneous Integration in Thin Packages

Miniaturized Fully-Passive Wireless Neural Recording with Heterogeneous Integration in Thin Packages

Fully Passive Flexible Wireless Neural Recorder for the Acquisition of Neuropotentials from a Rat Model

Appendix A Antennas and Sensors for Medical Applications: A Representative Literature Review

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