Oscillator-Based Reactance Sensors With Injection Locking for High-Throughput Flow Cytometry Using Microwave Dielectric Spectroscopy
Oscillator-Based Reactance Sensors With Injection Locking for High-Throughput Flow Cytometry Using Microwave Dielectric Spectroscopy
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DOI：
10.1109/jssc.2015.2500362
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发表时间：
2016-02-01
影响因子：
5.4
通讯作者：
Niknejad, Ali M.
中科院分区：
文献类型：
--
作者：
Chien, Jun-Chau;Niknejad, Ali M.
本文介绍了分析和设计的干扰器为基础的电抗传感器，采用注入锁定高通量无标记单细胞分析，在微波频率下使用介电谱。通过用I/Q激励源注入锁定两个感测LC振荡器，通过具有注入强度相关的换能器增益的相位检测来执行由与电磁场的相互作用引起的样品诱导的频移的测量。由注入锁定提供的这种固有相位放大不仅放松了对读出电路的设计要求，而且还保持了对与电源电压和环境参数的漂移相关联的共模误差的最高抑制。为了减少闪烁噪声的贡献，斩波技术采用相位调制。此外，本文提出了一种新的乒乓斩波方法，以减轻斩波引起的直流失调。在该原型中，覆盖6.5和30 GHz之间的频率的四个感测通道沿沿着用标准光刻法制造的微流体通道分布。测量结果表明，所提出的微波电容传感器在100 kHz滤波带宽下实现了亚aF（rms）的噪声灵敏度，使测量吞吐量超过1 k cells/s。该传感器原型采用65 nm CMOS工艺实现，在1 V电源下功耗为65 mW。
This paper presents the analysis and design of oscillator-based reactance sensors employing injection locking for high-throughput label-free single-cell analysis using dielectric spectroscopy at microwave frequencies. By injection-locking two sensing LC-oscillators with an I/Q excitation source, the measurement of the sample-induced frequency shift caused by the interaction with the electromagnetic fields is performed through phase detection with injection-strength-dependent transducer gain. Such inherent phase amplification offered by the injection locking not only relaxes the design requirement for the readout circuits but also maintains the highest rejection against common-mode errors associated with the drift of the supply voltage and the environmental parameters. To reduce flicker noise contribution, a chopping technique employing phase modulation is exploited. In addition, this paper presents a novel ping-pong chopping approach to alleviate chopping-induced dc offset. In this prototype, four sensing channels, covering frequencies between 6.5 and 30 GHz, are distributed along a microfluidic channel fabricated with standard photolithography. Measurements show that the proposed microwave capacitive sensors achieve a sub-aF(rms) of noise sensitivity at 100 kHz filtering bandwidth, enabling measurement throughput exceeding 1 k cells/s. The sensor prototype is implemented in 65 nm CMOS technology and consumes 65 mW at 1 V supply.