Costanzo Ian, Sen Devdip, McNeill John, Guler Ulkuhan
Department of Electrical and Computer Engineering, Worcester Polytechnic Institute, Worcester, MA 01609 USA.
IEEE J Solid-State Circuits. 2025 Aug;60(8):2905-2919. doi: 10.1109/jssc.2024.3512472. Epub 2024 Dec 20.
This article presents a novel technique that is immune to offset, enabling precise determination of the lifetime of luminescent materials. The technique is specifically applied to measure transcutaneous oxygen, an indicator of oxygen that diffuses through the skin and reflects arterial oxygen levels. Unlike intensity-based measurements, lifetime-based luminescence measurements are superior because they decouple oxygen information from confounding factors. The technique presented in this work involves measuring the time difference between fixed-voltage steps to extract the time constant of a decaying exponential, which represents the lifetime of luminescence. We propose a novel switched-capacitor circuit that enables long integration times and prevents the front-end amplifier from saturating. The analog subsystem was realized in 180-nm CMOS technology via a transimpedance amplifier (TIA) with a gain bandwidth product of 10 MHz, a comparator, and a switched capacitor circuit. The measured mean error is as accurate as 1.9% without postprocessing. During a 130 s measurement period, the readout circuit consumes a maximum of 16 J per calculation with a . Preliminary human subject tests have demonstrated that the sensor can effectively detect changes in transcutaneous oxygen levels resulting from arterial occlusion.
本文介绍了一种不受偏移影响的新技术，能够精确测定发光材料的寿命。该技术专门用于测量经皮氧含量，经皮氧是一种通过皮肤扩散并反映动脉氧水平的氧指标。与基于强度的测量不同，基于寿命的发光测量更具优势，因为它们能将氧信息与混杂因素分离。本文所介绍的技术涉及测量固定电压阶跃之间的时间差，以提取衰减指数的时间常数，该时间常数代表发光寿命。我们提出了一种新型开关电容电路，该电路能实现长积分时间并防止前端放大器饱和。模拟子系统采用180纳米CMOS技术，通过增益带宽积为10兆赫兹的跨阻放大器（TIA）、比较器和开关电容电路实现。未经后处理时，测量的平均误差精确至1.9%。在130秒的测量周期内，读出电路每次计算最多消耗16焦耳能量，功耗为 。初步人体受试者测试表明，该传感器能够有效检测动脉阻塞引起的经皮氧水平变化。
