Microfabrication, Coil Characterization, and Hermetic Packaging of Millimeter-Sized Free-Floating Neural Probes

Yeon, Pyungwoo; Rajan, Sreejith Kochupurackal; Falcone, Jessica; Gonzalez, Joe L.; May, G.S.; Bellamkonda, Ravi V.; Brand, Oliver; Bakir, Muhannad S.; Ghovanloo, Maysam

doi:10.1109/jsen.2021.3068077

Cited by 7 publications

(4 citation statements)

References 45 publications

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“…The proposed system can examine either physical or material induced encapsulation failures of wireless IMDs as small as 1.3 × 1.3 mm 2 . [ 25,30 ] Furthermore, this system along with the IDC integrated LC sensors provides a proof‐of‐concept for early nondestructive manufacturing quality check by sampling or annualized failure rate calculation through targeted reliability testing for broader consumer electronics not limited to wireless IMDs.…”

Section: Discussionmentioning

confidence: 99%

Automated and Wireless Accelerated Heat Soak Testing System to Assess Hermetic Failure Mechanism of Inductively Powered Implantable Medical Applications

Yeon

Kim

Wang

et al. 2023

Adv Materials Technologies

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Reliability and lifetime estimation of implantable medical devices (IMDs) is one of the essential steps in their design and development. As any failure of IMDs can result in serious health risks for the patients, they should be guaranteed not to fail over their intended lifetime under the harsh body fluidic and chemical environments. Traditional leak tests are applicable to large cm-scale IMDs, and they are often destructive, laborious, and costly. This paper presents an automated and wireless accelerated heat soak testing system to assess hermetic failure mechanisms in small mm-sized inductively powered IMDs. A high-throughput readout coil array printed circuit board can test hermeticity of multiple mm-sized wireless IMDs simultaneously in a harsh environment (e.g., 45 °C/90% RH with an error range of ±0.2% for 18 days gage repeatability and reproducibility test). An accelerated heat soak test is performed to evaluate the electronic durability and estimate the lifetime of the IMDs. This work focuses on validating the proposed system interrogating with eight inductor-capacitor sensors, composed of an interdigitated capacitive sensor connected to an inductor patterned polyimide substrate, to examine hermetic failure mechanisms of parylene-C encapsulation for wireless IMDs as well as broader miniature-sized consumer electronics.

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Section: Discussionmentioning

confidence: 99%

Automated and Wireless Accelerated Heat Soak Testing System to Assess Hermetic Failure Mechanism of Inductively Powered Implantable Medical Applications

Yeon

Kim

Wang

et al. 2023

Adv Materials Technologies

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“…This leads to serious scarring and affects the quality of the recording [8]. Hence, a miniature and wideband wireless link that transmits sensor data across the dura (a brain protection tissue) and scalp is a critical part to make the MEA "free-floating," less invasive surgically, and offer a highly preferable option in clinics [8]- [10].…”

Section: Introductionmentioning

confidence: 99%

Galvanic-Coupled Trans-Dural Data Transfer for High-Bandwidth Intracortical Neural Sensing

Shi

Song

Gao

et al. 2022

IEEE Trans. Microwave Theory Techn.

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A digital-impulse galvanic coupling as a new high-speed trans-dural (from cortex to the skull) data transmission method has been presented in this paper. The proposed wireless telemetry replaces the tethered wires connected in between implants on the cortex and above the skull, allowing the brain implant to be "free-floating" for minimizing brain tissue damage. Such trans-dural wireless telemetry must have a wide channel bandwidth for high-speed data transfer and a small form factor for minimum invasiveness. To investigate the propagation property of the channel, a finite element model is developed and a channel characterization based on a liquid phantom and porcine tissue is performed. The results show that the trans-dural channel has a wide frequency response of up to 250 MHz. Propagation loss due to micro-motion and misalignments is also investigated in this work. The result indicates that the proposed transmission method is relatively insensitive to misalignment. It has approximately 1 dB extra loss when there is a horizontal misalignment of 1mm. A pulse-based transmitter ASIC and a miniature PCB module are designed and validated ex-vivo with a 10-mm thick porcine tissue. This work demonstrates a high-speed and miniature in-body galvanic-coupled pulse-based communication with a data rate up to 250 Mbps with an energy efficiency of 2 pJ/bit, and has a small module area of only 26 mm 2 .

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“…PDMS is an important material for biological application including neural interface [18][19][20][21][22][23][24], but it is not easy to accurately remove the PDMS encapsulation layer due to its chemical inertness and mechanical softness. Of course, PDMS film can be easily mechanically punched with relatively low spatial resolution.…”

Section: Introductionmentioning

confidence: 99%

Cold Laser Micro-Machining of PDMS as an Encapsulation Layer for Soft Implantable Neural Interface

et al. 2022

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PDMS (polydimethylsiloxane) is an important soft biocompatible material, which has various applications such as an implantable neural interface, a microfluidic chip, a wearable brain–computer interface, etc. However, the selective removal of the PDMS encapsulation layer is still a big challenge due to its chemical inertness and soft mechanical properties. Here, we use an excimer laser as a cold micro-machining tool for the precise removal of the PDMS encapsulation layer which can expose the electrode sites in an implantable neural interface. This study investigated and optimized the effect of excimer laser cutting parameters on the electrochemical impedance of a neural electrode by using orthogonal experiment design. Electrochemical impedance at the representative frequencies is discussed, which helps to construct the equivalent circuit model. Furthermore, the parameters of the equivalent circuit model are fitted, which reveals details about the electrochemical property of neural electrode using PDMS as an encapsulation layer. Our experimental findings suggest the promising application of excimer lasers in the micro-machining of implantable neural interface.

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Microfabrication, Coil Characterization, and Hermetic Packaging of Millimeter-Sized Free-Floating Neural Probes

Cited by 7 publications

References 45 publications

Automated and Wireless Accelerated Heat Soak Testing System to Assess Hermetic Failure Mechanism of Inductively Powered Implantable Medical Applications

Automated and Wireless Accelerated Heat Soak Testing System to Assess Hermetic Failure Mechanism of Inductively Powered Implantable Medical Applications

Galvanic-Coupled Trans-Dural Data Transfer for High-Bandwidth Intracortical Neural Sensing

Cold Laser Micro-Machining of PDMS as an Encapsulation Layer for Soft Implantable Neural Interface

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