Bhusal Anant, Farahmand Masoud, Hasan Md Sadique, Vasudevan Sandhya, Vogt William C, Ibarra Bryan, Weininger Sandy, Scully Christopher G, Frank Zhang X, Chen Yu, Pfefer T Joshua
University of Massachusetts, Department of Biomedical Engineering, Amherst, Massachusetts, United States.
Food and Drug Administration, Center for Devices and Radiological Health, Silver Spring, Maryland, United States.
J Biomed Opt. 2024 Jun;29(Suppl 3):S33314. doi: 10.1117/1.JBO.29.S3.S33314. Epub 2025 Jan 7.
Pulse oximeter measurements are commonly relied upon for managing patient care and thus often require human testing before they can be legally marketed. Recent clinical studies have also identified disparities in their measurement of blood oxygen saturation by race or skin pigmentation.
The development of a reliable bench-top performance test method based on tissue-simulating phantoms has the potential to facilitate pre-market assessment and the development of more accurate and equitable devices. To generate phantoms capable of mimicking physical mechanisms and providing realistic results, customized tissue-mimicking materials (TMMs) are needed.
We focused on the development of channelized finger phantoms based on flexible silicone elastomers and their implementation in a pulsatile pressurized fluid network. Candidate TMMs were formulated to achieve a range of biologically relevant mechanical and optical properties by modifying components and curing protocols.
Our final optimized TMM had a Shore OO hardness of 32 and an elastic modulus of 130 kPa. TMM samples with sub-millimeter diameter channels exhibited compliance-increase in channel diameter with internal fluid pressure, as measured by optical coherence tomography-that was linearly dependent on internal pressure. Phantoms implemented in the pressurized network with an absorber-doped fluid and measured by a photoplethysmographic (PPG) sensor displayed tunable modulation levels ranging from 0.6% to 18.1% at 940 nm. Finally, we demonstrated that the system could be used to generate measurements in several clinical pulse oximeters and variations in PPG waveform could be produced by varying the simulated epidermal melanin content.
Overall, we provide significant insights into potential best practices for creating silicone-based tissue phantom tools for pulse oximetry performance testing.
脉搏血氧仪测量常用于患者护理管理，因此在合法上市前通常需要进行人体测试。最近的临床研究还发现，其在测量血氧饱和度时存在因种族或皮肤色素沉着而产生的差异。
基于组织模拟体模开发一种可靠的台式性能测试方法，有可能促进上市前评估以及开发更准确和公平的设备。为了生成能够模拟物理机制并提供逼真结果的体模，需要定制的组织模拟材料（TMM）。
我们专注于基于柔性硅橡胶弹性体制备通道化手指体模，并将其应用于脉动加压流体网络中。通过修改成分和固化方案，配制候选TMM以实现一系列与生物学相关的机械和光学特性。
我们最终优化的TMM邵氏OO硬度为32，弹性模量为130 kPa。通过光学相干断层扫描测量，直径小于一毫米的通道的TMM样品在内部流体压力作用下通道直径的顺应性增加，且与内部压力呈线性相关。在加压网络中使用掺杂吸收剂的流体并通过光电容积脉搏波描记法（PPG）传感器测量的体模，在940 nm处显示出可调的调制水平，范围为0.6%至18.1%。最后，我们证明该系统可用于在几种临床脉搏血氧仪中进行测量，并且通过改变模拟表皮黑色素含量可以产生PPG波形的变化。
总体而言，我们为创建用于脉搏血氧仪性能测试的硅基组织体模工具的潜在最佳实践提供了重要见解。
