Electrical and chemical characterizations of hafnium (IV) oxide films for biological lab-on-a-chip devices

Collins, Jeana; Hernandez, H. Moncada; Habibi, Sanaz; Kendrick, Chito; Wang, Z.; Bihari, Nupur; Bergstrom, Paul L.; Minerick, Adrienne R.

doi:10.1016/j.tsf.2018.07.024

Cited by 18 publications

(29 citation statements)

References 54 publications

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“…Use as an optical coating material is another major application of HfO 2 [43,46]. With positive results regarding the in vitro biocompatibility of HfO 2 in terms of cytotoxicity, hemolysis, and cell imaging [47,48,49] along with the inherently excellent property of HfO 2 as a barrier against liquid water, its applications have been extended to include uses in biological devices, such as in biocompatible passivation or the functionalization of biosensors [49,50,51,52].…”

Section: Inorganic Materialsmentioning

confidence: 99%

Emerging Encapsulation Technologies for Long-Term Reliability of Microfabricated Implantable Devices

2019

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The development of reliable long-term encapsulation technologies for implantable biomedical devices is of paramount importance for the safe and stable operation of implants in the body over a period of several decades. Conventional technologies based on titanium or ceramic packaging, however, are not suitable for encapsulating microfabricated devices due to their limited scalability, incompatibility with microfabrication processes, and difficulties with miniaturization. A variety of emerging materials have been proposed for encapsulation of microfabricated implants, including thin-film inorganic coatings of Al2O3, HfO2, SiO2, SiC, and diamond, as well as organic polymers of polyimide, parylene, liquid crystal polymer, silicone elastomer, SU-8, and cyclic olefin copolymer. While none of these materials have yet been proven to be as hermetic as conventional metal packages nor widely used in regulatory approved devices for chronic implantation, a number of studies have demonstrated promising outcomes on their long-term encapsulation performance through a multitude of fabrication and testing methodologies. The present review article aims to provide a comprehensive, up-to-date overview of the long-term encapsulation performance of these emerging materials with a specific focus on publications that have quantitatively estimated the lifetime of encapsulation technologies in aqueous environments.

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Section: Inorganic Materialsmentioning

confidence: 99%

Emerging Encapsulation Technologies for Long-Term Reliability of Microfabricated Implantable Devices

2019

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“…These properties have led HfO 2 to use as a high-κ gate dielectric material to replace silicon dioxide in CMOS semiconductor industry, [34,35] and as an optical coating material. [37,38] In vitro biocompatibility of HfO 2 has been demonstrated by cell viability test follwing the standard guideline of ISO 10993-5, [39,40] hemolysis test, [41] and imaging of cultured cell, [42] all of which have verified non-cytotoxicity and biocompatibility of HfO 2 films. Recently HfO 2 has been increasingly utilized in biological applications as a biocompatible passivation or functionalization layer for lab-on-a-chip devices or biosensors, where HfO 2 stability in aqueous solution and good passivation proeperties were demonstrated.…”

Section: Introductionmentioning

confidence: 99%

“…Recently HfO 2 has been increasingly utilized in biological applications as a biocompatible passivation or functionalization layer for lab-on-a-chip devices or biosensors, where HfO 2 stability in aqueous solution and good passivation proeperties were demonstrated. [41,[43][44][45] While HfO 2 has not yet been applied for implantable medical devices, these results encouraged us to explore the capability of HfO2 as an hermetic packaging material for the microscale devices desccribed below. As a transparent material complement, SiO 2 was chosen due to its adhesion properties including ease of hydrophobic/hydrophilic surface manipulation.…”

Section: Introductionmentioning

confidence: 99%

Conformal Hermetic Sealing of Wireless Microelectronic Implantable Chiplets by Multilayered Atomic Layer Deposition (ALD)

Jeong

Laiwalla

Lee

et al. 2018

Adv Funct Materials

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A hermetic sealing method of sub-mm sized microelectronic chiplets for wireless body implants is presented by ultrathin and electromagnetically transparent Atomic Layer Deposition (ALD) coatings. Fully 3-dimensional (3D) conformal encapsulation of wirelessly powered microdevices is demonstrated both with and without opening windows for electrophysiological measurements. The chiplets embedding custom CMOS application specific integrated circuits (ASICs) with RF transmitters are encapsulated by a stack of alternating layers of Hafnium oxide (HfO 2 ) and Silicon dioxide (SiO 2 ) as the strategy to maximize impermeability of water and ionic penetration while minimizing the volume of the packaging material. The hermeticity of the devices is characterized through accelerated aging tests in saline at T=87˚C while continued functionality is monitored via evaluation of backscattered RF signals (near 1 GHz) to ascertain possible degradation and electronic failure. Earliest failures of wirelessly functional devices have occurred after more than 180 days of immersion at 87˚C. Wireless device having opening windows through ALD envelope have not shown any signs of degradation for more than 95 days so far. This implies an equivalent lifetime >10 years at T=37˚C. This approach is readily scalable to high throughput batch processing of hundreds of microchiplets, offering a methodology for hermetic packaging of microscale biomedical chronic implants.

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“…Orthogonally positioned Ti/Au (50/50 nm thickness, 100 µm width) electrode pairs with 100 μm gaps were designed and fabricated following standard soft photolithography fabrication procedures on microscope slides [30]. Additionally, a layer of 100 nm hafnium dioxide (HfO2) was sputter coated over the entire glass slide to provide a physical dielectric barrier above the electrode [29]. Fig.…”

Section: Microdevice Design and Fabricationmentioning

confidence: 99%

“…To test our hypothesis, ionized fluorescent dye Fluorescein isothiocyanate (FITC), was used as a real-time detectable target. To suppress the dominant Faradaic reaction manifesting as water electrolysis, 1) methanol (MeOH) was used as a solvent instead of water [28], and 2) a dielectric layer of hafnium dioxide (HfO2) was implemented over the Ti/Au electrode to block the electron exchange between the electrode metal surface to any residual water molecules [29].…”

Section: Introductionmentioning

confidence: 99%

Reaction-free concentration gradient generation in spatially non-uniform AC electric fields

Minerick

2022

Preprint

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The ability to generate stable, spatiotemporally controllable concentration gradients is critical for both electrokinetic and biological applications such as directional wetting and chemotaxis. Electrochemical techniques for generating solution and surface gradients display benefits such as simplicity, controllability, and compatibility with automation. Here, we present an exploratory study for generating micro-scale spatiotemporally controllable gradients using a reaction-free electrokinetic technique in a microfluidic environment. Methanol solutions with ionic Fluorescein isothiocyanate (FITC) molecules were used as an illustrative electrolyte. Spatially non-uniform alternating current (AC) electric fields were applied using hafnium dioxide (HfO2) coated Ti/Au electrode pairs. Results from spatial and temporal analysis, along with control experiments suggest that the FITC ion concentration gradient in bulk fluid (over 50 µm from the electrode) was established due to spatial variation of electric field density, and was independent of electrochemical reactions at the electrode surface. The established ion concentration gradients depended on both amplitudes and the frequencies of the oscillating AC electric field. Overall, this work reports a novel approach for generating stable and spatiotemporally tunable gradients in a microfluidic chamber using a reaction-free electrochemical methodology.

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Electrical and chemical characterizations of hafnium (IV) oxide films for biological lab-on-a-chip devices

Cited by 18 publications

References 54 publications

Emerging Encapsulation Technologies for Long-Term Reliability of Microfabricated Implantable Devices

Emerging Encapsulation Technologies for Long-Term Reliability of Microfabricated Implantable Devices

Conformal Hermetic Sealing of Wireless Microelectronic Implantable Chiplets by Multilayered Atomic Layer Deposition (ALD)

Reaction-free concentration gradient generation in spatially non-uniform AC electric fields

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