ACADEMIC RESEARCH•學術研究 2020 UMAGAZINE 22•澳大新語 58 該可攜式核磁共振系統之核心為一粒 客製化CMOS芯片，內含脈衝序列合成 器、發射器和接收器各一個。脈衝序列 合成器會產生不同種類的脈衝序列，這 些序列會控制原子核的自轉方式和反 應。通過製造不同種類的脈衝序列，我 們就能獲取研究樣本的各種資訊。發射 器則會放大由脈衝序列合成器產生的激 勵訊號，並引導訊號到射頻線圈，讓線 圈產生磁場並激發原子核。與射頻線圈 連接的接收器會擷取並放大來自線圈的 微弱訊號，用作過濾或頻率轉換等後續 處理。整個CMOS芯片的裸片只有四平 方毫米。 無論一般還是小型化版本的核磁共振系 統，都存在著吞吐量較低之先天缺點。 由於樣本的核磁共振訊號通常以微伏特 計，非常微弱，研究人員要重複多輪實 驗才能改善擷取結果的訊號雜訊比（訊 噪比）。另一方面，原子核受發射器激 發後要花數秒才能回復至熱平衡以繼續 下次實驗，直接限制了其重複擷取之速 率，並降低了實驗的通量。因此，要獲 取解析度理想的共振訊號，往往要花上 sample management by integrating a digital microfluidic platform with the NMR system (Pictures 1 and 2)1, while the latest generation, on which we collaborated with the research group of Prof Donhee Ham at Harvard University, focuses on portable NMR with parallelism to expedite the NMR experiment for faster screening (Picture 3). Herein, we briefly discuss the key features of this latest research2. At the heart of the portable NMR system is the customised CMOS IC. It mainly includes a pulse sequence synthesiser, a transmitter, and a receiver. The pulse sequence synthesiser generates different kinds of pulse sequences for the NMR experiments. The pattern of the pulse sequence manipulates the spinning of the nuclei and determines the responses from them. Hence, different information from the samples can be obtained by varying the pulse sequences. The transmitter amplifies the excitation signals generated by the pulse sequence synthesiser and drives the signals into the radio-frequency coil, which excites the nuclei. The receiver, which is connected to the same radio-frequency coil, picks up the diminutive signals from the coil and amplifies the signals for subsequent processing, such as filtering and frequency‑conversion. The size of the CMOS IC die is only 4 mm2. 圖二： 第一代可攜式核磁共振系 統使用的CMOS芯片1 Picture 2: The photo of the CMOS IC for our first portable NMR system1
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