應用於生醫電刺激器中動態阻抗之自動調整刺激時間的脈衝寬度調變控制器

摘要神經電刺激在神經功能失調治療和神經損傷康復中具有極其重要的作用。隨著微電子控制技術，電腦技術以及神經科學的發展，神經電刺激已經從傳統的經由皮層電刺激逐漸發展到植入式電刺激階段，目前植入式神經電刺激在治療和控制帕金森病，癲癇，慢性疼痛，聽視覺障礙等多個方面已經取得了較大進展。本論文的設計為一個控制植入式生理電刺激器的控制器以及電刺激器。電刺激器必須透過電極作為介面才能對神經或肌肉進行電刺激的動作，然而電極－組織介面阻抗可能因電極本體受刺激電流、環境等因素而產生變化，或者受接觸不良、電極大小與材質的影響，例如視網膜是一個弧狀的面，所以不同位置的電極，接觸到組織形成的阻抗值亦會不同，其變異範圍在10KΩ– 100KΩ，所以對於不同的介面阻抗值，必須調整刺激週期使得刺激電荷量可以達到有效的電刺激，此時如果沒有依照阻抗的變化量予以控制增減刺激的電荷量，會導致所需要的刺激量和施予細胞的刺激量出現不相等的現象，並且當刺激量超過某一定程度之後，便有可能產生永久性的細胞傷害。為了讓電刺激器能滿足阻抗變異的需求，根據阻抗變異與電刺激參數的設定，論文中提出了一個可以根據介面阻抗不同而自動調整刺激時間的控制器，此控制器能依照每次的刺激阻抗不同而自動調整所需要的刺激時間週期，一方面使得刺激的組織得到需要的刺激量，另一方面保護刺激過量導致組織損壞。電刺激器則是利用產生三倍供應電壓輸出的高電壓輸出級驅動電路，並以台積電0.18μm互補式金氧半導體的標準製程實現，其好處是不需花費其他昂貴的特殊製程，又可以與其他電路整合於同一晶片。

關鍵字

寬度調變；動態阻抗；電刺激；生醫

並列摘要

Abstract Functional Neuromuscular Stimulation plays an important role in the treatment of nervous diseases and rehabilitation of nerve injury. With the rapid development of microelectronic technology, bio-technology and Neuroscience, Functional Neuromuscular Stimulation has been transformed from a traditional electrical stimulation to implantable electrical stimulation, and got great progress in Parkinson, Epilepsy, Chronic Pain and others visual diseases. This thesis aims to design an electrical stimulator controller for implanted visual prosthesis. The designed electrical stimulator stimulates nerves or muscles using electrodes as the interface. Generally the impedance of electrode-tissue interface may change in the rage of 10KΩ – 100KΩ due to electrode itself such as poor contact, the electrode size, material differences, and stimulus current and environmental factors. It is necessary to adjust the stimulus period to get correct electrical charge, otherwise, will induce the difference between theoretical electrical charge and real electrical charge, and sometimes will damage the cell permanently. This thesis proposes a new impedance measurement circuit called PWM-based auto-tuning electrical charge timing controller, ahead of the stimulation circuit, to prevent inaccurate electrical charge and protect histiocyte. The width of the digital pulse width modulator can be varied automatically, based on different interface impedances. That means the stimulus period can be auto-adjusted with dynamic impedance to get required electrical charge and best effect. Besides, the electrical stimulator is designed by a high voltage output driver which can generate three times supply voltage output. The whole design is implemented in TSMC 0.18-μm standard CMOS technology to demonstrate the feasibility of the proposed electrical stimulator. An advantage is that it can be fully integrated with other circuits without extra processing costs.

並列關鍵字

Biomedical Electrical ； PWM ； Stimulator ； Electric Charge

參考文獻

[4] M. Sivapralasam, W. Liu, G. Wang, J. D. Weiland, and M. S. Humayun, “Architecture tradeoffs in high-density microstimulators for retinal prosthesis,” IEEE Transactions on Circuits and Systems, vol. 52, no. 12, pp. 2629-2641, Dec. 2005.

[5] D. R. McNeal, R. J. Nakai, P. Meadows, and W. Tu, “Open-loop control of the freely-swinging paralyzed leg,” IEEE Trans. Biomed. Eng., vol. 36, no. 9, pp.895-905, Sep. 1989.

[7] M. Mahadevappa, J. D. Weiland, D. Yanai, I Fine, R. J. Greenberg, and M. S. Humayun, “Perceptual thresholds and electrode impedance in three retinal prosthesis subjects,” IEEE Trans. Neural Syst. Rehabil. Eng., vol. 13, no. 2, pp. 201-206, Jun. 2005.

[8] M. Sivaprakasam, W. Liu, M. S. Humayun, and J. D. Weiland, “A variable range bi-phasic current stimulus driver circuitry for an implantable retinal prosthetic device,” IEEE Journal of Solid-State Circuits, vol. 40, no. 3, pp. 763-771, Mar. 2005.

[9] L. S. Y. Wong, S. Hossain, A. Ta, J. Edvinsson, D. H. Rivas, and H. Naas, “A very low-power CMOS mixed-signal IC for implantable pacemaker applications,” IEEE J. Solid-State Circuits, vol. 39, no. 12, pp. 2446-2456, Dec. 2004.

國際替代計量

應用於生醫電刺激器中動態阻抗之自動調整刺激時間的脈衝寬度調變控制器

未授權

主題瀏覽