Effect of bias voltage and temperature on lifetime of wireless neural interfaces with Al 2O3 and parylene bilayer encapsulation.
Biomed Microdevices
; 17(1): 1, 2015 Feb.
Article
en En
| MEDLINE
| ID: mdl-25653054
ABSTRACT
The lifetime of neural interfaces is a critical challenge for chronic implantations, as therapeutic devices (e.g., neural prosthetics) will require decades of lifetime. We evaluated the lifetime of wireless Utah electrode array (UEA) based neural interfaces with a bilayer encapsulation scheme utilizing a combination of alumina deposited by Atomic Layer Deposition (ALD) and parylene C. Wireless integrated neural interfaces (INIs), equipped with recording version 9 (INI-R9) ASIC chips, were used to monitor the encapsulation performance through radio-frequency (RF) power and telemetry. The wireless devices were encapsulated with 52 nm of ALD Al2O3 and 6 µm of parylene C, and tested by soaking in phosphate buffered solution (PBS) at 57 °C for 4× accelerated lifetime testing. The INIs were also powered continuously through 2.765 MHz inductive power and forward telemetry link at unregulated 5 V. The bilayer encapsulated INIs were fully functional for â¼35 days (140 days at 37 °C equivalent) with consistent power-up frequencies (â¼910 MHz), stable RF signal (â¼-75 dBm), and 100 % command reception rate. This is â¼10 times of equivalent lifetime of INIs with parylene-only encapsulation (13 days) under same power condition at 37 °C. The bilayer coated INIs without continuous powering lasted over 1860 equivalent days (still working) at 37 °C. Those results suggest that bias stress is a significant factor to accelerate the failure of the encapsulated devices. The INIs failed completely within 5 days of the initial frequency shift of RF signal at 57 °C, which implied that the RF frequency shift is an early indicator of encapsulation/device failure.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Polímeros
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Xilenos
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Ensayo de Materiales
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Electrodos Implantados
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Óxido de Aluminio
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Tecnología Inalámbrica
Idioma:
En
Revista:
Biomed Microdevices
Asunto de la revista:
ENGENHARIA BIOMEDICA
Año:
2015
Tipo del documento:
Article