Towards Low-Cost, High-Sensitivity Point-of-Care Diagnostics Using VCO-Based ESR-on-a-Chip Detectors
Towards Low-Cost, High-Sensitivity Point-of-Care Diagnostics Using VCO-Based ESR-on-a-Chip Detectors
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DOI：
10.1109/jsen.2018.2875767
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发表时间：
2019-10
影响因子：
4.3
通讯作者：
Benedikt Schlecker;A. Hoffmann;Anh Chu;M. Ortmanns;K. Lips;J. Anders
中科院分区：
文献类型：
--
作者：
Benedikt Schlecker;A. Hoffmann;Anh Chu;M. Ortmanns;K. Lips;J. Anders
在本文中，我们提出了一种新的架构，用于压控振荡器（VCO）为基础的电子自旋共振（ESR）检测的便携式，即时护理ESR光谱仪的未来使用。所提出的架构以一个专用集成电路（ASIC）为中心，其中包含一个基于VCO的ESR检波器，该检波器具有两个不同的调谐端口，VCO增益差异很大，可实现宽频率扫描和小信号频率调制，同时保持对驱动端口的数模转换器的要求易于管理。此外，所提出的ASIC具有第二个VCO，用于通过混频进行片内下变频。为了从外部基准电压源精确推导工作频率（这是定量ESR实验所需的），两个片内VCO被嵌入到一个失调锁相环中。所提出的架构进行了验证与ESR实验上常用的ESR标准样品（DPPH和BDPA）。在这些实验中，在$B_{0} = {450} {\text {mT}}$下，使用永磁体和现场可编程门阵列上的低成本信号处理，实现了1.7\times10 ^{9}~{\text {spins}/（\text {G}\sqrt {\text {Hz}}）}$的自旋灵敏度，这与现有技术水平相当。所提出的概念验证实验清楚地证明了所提出的基于VCO的ESR检测系统在未来床旁应用中的潜力。
In this paper, we present a new architecture for a voltage-controlled oscillator (VCO)-based electron spin resonance (ESR) detection for a future use in portable, point-of-care ESR spectrometers. The proposed architecture is centered around an application-specified integrated circuit (ASIC) containing a VCO-based ESR detector with two distinct tuning ports with largely different VCO gains to enable wide frequency sweeps and small-signal frequency modulations while keeping the requirements on the digital-to-analog converter driving the ports manageable. In addition, the proposed ASIC features a second VCO for an on-chip frequency downconversion via mixing. To allow for a precise derivation of the operating frequency from an external reference as it is required for quantitative ESR experiments, the two on-chip VCOs are embedded into an offset phase-locked loop. The proposed architecture is verified with ESR experiments on commonly used ESR standard samples (DPPH and BDPA). In these experiments, a spin sensitivity of $1.7\times 10^{9}~{\text {spins}/(\text {G}\sqrt {\text {Hz}})}$ has been achieved at $B_{0} = {450} {\text {mT}}$ , which is comparable to the state of the art, using a permanent magnet and low-cost signal processing on an field-programmable gate array. The presented proof-of-concept experiments clearly demonstrate the potential of the proposed VCO-based ESR detection system for future point-of-care applications.