以微控制器研製高準確度阻抗量測系統

Abstract

生物電阻抗分析 (Bioelectrical Impedance Analysis, BIA) 是利用不同的生物組織，其具有不同的結構組成，藉以擷取出所需的相關生物資訊，近年來被廣泛應用於人體病理樣本檢測上，但不論被應用於何種生物組織，其量測硬體與後端的演算皆相當重要。傳統的 LCR 量測儀固然精準，硬體空間與消耗功率不利於攜帶，且從前阻抗量測的計算方式，往往侷限於時間解析度的不足，無法區分極小的相位改變，導致量測出的電阻與電抗與實際數值有相當的差異。 本研究開發了低頻率的高準確度阻抗量測平台，以德州儀器 (TI) 之 MSP430 微控制器作為系統核心並整合其他周邊的子系統與設備，最終使用標準元件來模擬簡單的組織模型，結果與現有 LCR Meter 比較，用以確定系統之準確度與可靠性之評估，且達到可攜式、低成本、自動量測以及即時顯示等優點，提升日後對於阻抗量測的便利性。

Bioelectrical impedance analysis is based on that the different tissues have different characteristics to obtain the relevant biological information. It has been wildly used to detect much biological information for decades. No matter what kind of application, their measurement hardware and algorithm are very important. Traditional LCR meters are certainly accurate, however its size, and power consumption will make it difficult for portable applications. Furthermore, previous impedance measurement can not distinguish a very small amount of the phase change, leading to considerable deviation from the actual value. This study develop a low-frequency, high-accuracy impedance measurement platform. The system utilized a microcontroller, MSP430, as the core unit. It was compared with a LCR Meter to determine the accuracy and reliability. The resulting system is a portable, low-cost, automatic and real-time display device for the convenience of the impedance measurement.