High aspect ratio spiral microcoils fabricated by a silicon lost molding technique

Jiang, Yun; Ono, Takahito; Esashi, Masayoshi

doi:10.1088/0960-1317/16/5/025

Cited by 13 publications

(10 citation statements)

References 13 publications

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“…Researchers have used through-wafer silicon trenches as electroplating molds for interconnects in three dimensional packaging [19,20]. More recently, using through-wafer silicon trenches for magnetic lamination was studied [13] and a coreless RF inductor based on through-wafer silicon molds was demonstrated [21]. However, using silicon molding technique to construct a power inductor by stack multiple thick metal layers has not been reported.…”

Section: Performances Of the Integrated Power Inductors From Literaturementioning

confidence: 99%

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Design and Fabrication of Integrated Power Inductor Based on Silicon Molding Technology

Wang

Batarseh

Ngo

et al. 2007

2007 IEEE Power Electronics Specialists Conference

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This paper reports a new fabrication process that can be used to integrate high-power-density and low-loss inductors with silicon-based power ICs to realize monolithic integration of power converters for portable electronics applications. In this new process, copper is electroplated into through-wafer silicon trenches, resulting in thick copper windings (200~500 µm) and thus low winding resistance. The magnetic cores are electroplated on both sides of the silicon substrate to cover the copper windings, and through-wafer magnetic vias are used to close the magnetic path. Powder permalloy with relatively high resistivity (400 µ ·cm) and low permeability (40) are used to reduce the loss of large magnetic cores. The powder permalloy can be fabricated by using high-current-density electroplating without mixing or high temperature sintering. A pot-core inductor has been designed and fabricated. The inductance and saturation current of the designed inductor are 179 nH and 5 A, respectively. The measured winding resistance of the 200 µm thick copper winding is 23 m .

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Section: Performances Of the Integrated Power Inductors From Literaturementioning

confidence: 99%

“…Therefore it is possible that fully-integrated power converters can be fabricated by an IC foundry. In fact, a CMOS-MEMS process capable of fabricating deep-silicon trench structures has been developed for making integrated inertial sensors [21][22][23]. 4) The through-wafer metals and vias provide good thermal paths.…”

Section: Process Flowmentioning

confidence: 99%

Design and Fabrication of Integrated Power Inductor Based on Silicon Molding Technology

Wang

Batarseh

Ngo

et al. 2007

2007 IEEE Power Electronics Specialists Conference

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“…At high frequencies, skin and proximity effects increase the effective resistance of the coil [11]. The effective resistance can be estimated by the following equation,…”

Section: Inductive Power Linkmentioning

confidence: 99%

High Efficiency Double-Paired Inductive Coils for Wireless Powering of a Retinal Prosthesis

Ng¹,

Bai²,

Boyd³

et al. 2010

Mechatronic Systems and Control

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Wireless powering of a retinal prosthesis is necessary for continuous operation of the implanted device in a blind patient. Inductive link has the potential for transferring power wirelessly to such an implanted device inside the eye. However, constant motion of the eye and changes in electrode-tissue impedance results in a decrease in the inductive link efficiency. In this paper, we present a novel method to improve the efficiency of the inductive link by introducing an intermediate pair of coils to close the gap between two coils with large separation. Based on our theoretical formulation, the power transfer efficiency of the double-pair coil link is estimated to exceed the efficiency of a single-pair coil when the coupling coefficient can be improved by a conservative value of 3 times. We fabricated the double-pair coils using flexible printed circuit board technology. Measurement result confirms our initial expectation. By implementing this design, we aim to provide sufficient power for next generation retinal prosthesis which has electrode count exceeding 1000 and can consume upwards of 50 mW of power.

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“…The variables C 1 , C 2 and C 3 take the values 1; 2.46; and 0.2 respectively [13]. The impedance of the coil is due to the resistivity of the material, and skin effect and proximity effects [14]. The coil impedance can be calculated by adding the resistance of the coil due to skin effect, to the resistance due to proximity effect.…”

Section: Coil Fabricationmentioning

confidence: 99%

Closed-loop inductive link for wireless powering of a high density electrode array retinal prosthesis

Felic

Skafidas

et al. 2009

2009 Electromagnetic Compatibility Symposium Adelaide

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A retinal prosthesis intended for rehabilitation of vision impaired patients will require continuous power supply in order to achieve real-time moving images. In this work, we explore the use of inductive coils fabricated using flexible circuit technologies for inductive powering of the implanted prosthetic device. We found that manufacturing technologies dictate the optimum operating frequency of the coil. For a minimum track width and spacing of 4 mils, the optimum frequency was found to be 2.9 MHz. We also looked at the distribution of electric and magnetic fields generated by the inductive coils in and surrounding the eye. These simulation results show that there are electric field concentrations around the conductive coils. Apart from the coils, we need to design an efficient circuit to drive the transmit coil and recover the transmitted power. In order to maintain optimal operation of the link, a closed-loop load modulation feedback operation is proposed. Adaptive control using back-telemetry of the induced voltage on the secondary side can close the power supply loop and result in optimum power transfer by boosting the supply voltage on the primary side when load is high and reducing this voltage when load is small.

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High aspect ratio spiral microcoils fabricated by a silicon lost molding technique

Cited by 13 publications

References 13 publications

Design and Fabrication of Integrated Power Inductor Based on Silicon Molding Technology

Design and Fabrication of Integrated Power Inductor Based on Silicon Molding Technology

High Efficiency Double-Paired Inductive Coils for Wireless Powering of a Retinal Prosthesis

Closed-loop inductive link for wireless powering of a high density electrode array retinal prosthesis

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