We demonstrate a hybrid "package-less" polydimethylsiloxane (PDMS)-complementary-metal-oxide-semiconductor (CMOS)-FR4 system for contact imaging. The system embeds the CMOS image sensor directly in a PDMS layer instead of the standard chip package to support microfluidic structures much larger and more complex than those in prior art. The CMOS/PDMS layer is self-aligned to form a continuous, flat surface to provide structural support for upper microfluidic layers. The system consists of five layers of PDMS implementing fluid channels, valves, chambers, and inlets/outlets. A custom CMOS image sensor with integrated signal conditioning circuits directly captures light from sample fluid for high optical collection efficiency. Owing to the flexibility afforded by the integration process, the system demonstrates, for the first time, integrated valves in contact imaging. Moreover, we present the first direct comparison of the optical performance of a CMOS image sensor and a photomultiplier tube (PMT) in identical contact-imaging conditions. Measurements show that our CMOS sensor achieves 17 dB better signal-to-noise ratio (SNR) compared to a commercial PMT across a broad range of integration times, with a maximum SNR of 47 dB. Chemiluminescent testing successfully shows signal detection for different analyte concentrations and integration times. The contact-imaging system demonstrates a detection limit of 25 μM of a 9,10-diphenylanthracene-based solution.

中文翻译：

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用于微流体集成的无封装混合 PDMS-CMOS-FR4 接触成像系统的设计和表征。

我们展示了一种用于接触成像的混合“无封装”聚二甲基硅氧烷 (PDMS)-互补金属氧化物半导体 (CMOS)-FR4 系统。该系统将CMOS图像传感器直接嵌入PDMS层而不是标准芯片封装中，以支持比现有技术更大、更复杂的微流体结构。CMOS/PDMS 层自对准形成连续、平坦的表面，为上部微流体层提供结构支撑。该系统由五层 PDMS 组成，用于实现流体通道、阀门、腔室和入口/出口。具有集成信号调节电路的定制 CMOS 图像传感器直接捕获来自样品流体的光，以实现高光学收集效率。由于集成过程提供的灵活性，该系统首次展示了接触式成像中的集成阀。此外，我们首次对 CMOS 图像传感器和光电倍增管 (PMT) 在相同接触成像条件下的光学性能进行了直接比较。测量结果表明，与商用 PMT 相比，我们的 CMOS 传感器在较宽的积分时间范围内实现了 17 dB 更好的信噪比 (SNR)，最大 SNR 为 47 dB。化学发光测试成功地显示了不同分析物浓度和积分时间的信号检测。接触式成像系统对基于 9,10-二苯基蒽的溶液的检测限为 25 μM。