超音波換能器功率計系統設計

Design of a power meter for use with ultrasound transducers

吳益彰(Yi-Chang Wu)

指導教授 ： 馬亞尼

義守大學/醫學院/生物醫學工程學系/碩士(2019年)

摘要

使用超音波刺激細胞，當訊號發送端與負載端的阻抗不匹配時，將會產生反射波。
當反射波越小時，超音波的功率強度或是細胞在超音波治療時所接收到的強度會更有效。
本篇研究初代功率計主要使用型號為MAX2016的IC作為主控制與偵測器，這顆IC是在高頻條件下所使用的。設計電路完成後，我們設計了一系列的實驗來證明電路板與功率計的功能性與準確性。
此篇研究目標主要是設計在超音波刺激細胞下所使用的功率計，超音波換能器激發頻率大約在28 KHz，高頻功率計偵測頻率最低為100 MHz，所以我們選擇另一顆型號為 HMC612的IC來設計另一台超音波功率計。
超音波功率計包含以IC為主控制器的電路板和雙通道的耦合器，所選擇的MAX2016與HMC612 IC可以偵測超音波治療時入射跟反射的訊號。利用功率計知道確切的入射跟反射訊號，可以調整入射跟反射訊號的比例，而使反射訊號最小，讓目標可以接收到完整的超音波刺激。
在研究的最後，我們將設計的高頻與低頻功率計與美國生產製造的功率計比較，確認其功能與實用性是否有相似的特徵。此超音波系統也接上微處理器(Arduino uno)用來傳送與接收資料並可顯示功率數值在液晶螢幕上讓使用者能即時讀取。

關鍵字

超音波 ； 功率計 ； 雙向耦合器

並列摘要

Improper ultrasound propagation produces reflection waves. When the impedance at signal source is not the same as the impedance at the load side it will produce reflection waves.
The smaller the reflection wave, the more ultrasound power tissues or cells receive during ultrasound treatment.
The initial version of the power meter uses the MAX2016 IC as the main power sensor, this IC input range is for high frequencies. After testing its function and accuracy, we performed a series of experiments as shown in the results.
The target of this study is to design a power meter for use in low frequency ultrasound stimulation of cells and tissues. The ultrasound signal has low frequency which is around 28 kHz, so we select the HMC612 IC to design another power meter for low frequency.
The designed power meter contains a PCB and a bi-directional coupler, the MAX2016 and HMC612 IC can detect the forward and reverse signals during ultrasound treatment. Knowing the exact values of the forward and reverse signals allows for adjustment so that reflections can be minimized.
Finally, a commercial ultrasound power meter was compared with the MAX2016 and HMC612 based power meters to confirm that they have similar characteristic. The system was also connected to an Arduino board so that the user can read the power values on an LCD display.

並列關鍵字

ultrasound ； power meter ； bi-directional coupler ； MAX2016 IC ； HMC612 IC ； Arduino Uno

參考文獻

[1]Datasheet,https://datasheets.maximintegrated.com/en/ds/MAX2016.pdf, Rev 1, LF-to-2.5GHz Dual Logarithmic Detector/ Controller for, Power, Gain, and VSWR Measurements, MAX2016, 10/06.

[2]Datasheet,http://k6jca.blogspot.com/2015/01/notes-on-directional-couplers-for-hf.html,2018/06/04, Notes on Directional Couplers for HF, 2015.

[3]Datasheet,https://www.analog.com/media/en/technical-documentation/data-sheets/hmc612.pdf, Rev1, 75 dB LOGARITHMIC DETECTOR / CONTROLLER, 50 Hz - 3000 MHz, 2008

[4] Sung-Whan Kim, Hyun Aae Ryu, Yong Seung Lee, In Sil Jeong, Soonhag Kim, “Generation of directly reprogrammed human endothelial cells derived from fibroblast using ultrasound” Journal of Molecular and Cellular Cardiology, 126 (2019) 118–128.

[5] MICHIEL KOUWENHOVEN, BRUCE HEMP, Analog Devices, Inc, “RF detectors help solve system design challenges”, 2019.