基于气体浓度定量的嗅觉刺激器优化设计

现有的基于磁共振测量的嗅觉刺激器，通过调节嗅剂液体浓度的方法可以实现不同浓度的嗅觉刺激，但随着实验进行，受到嗅剂挥发以及实验环境（温度、湿度、气流量）变化的影响，很难确保输送至鼻腔的嗅剂气体浓度的稳定性，进而影响实验结果的准确性．本研究对本实验室前期开发的嗅觉刺激装置进行改进，实现了气体浓度精确定量．改进后的嗅觉刺激器主要分为三个部分：控制系统、反馈系统和气路系统．控制系统主要实现气路系统的送气控制和嗅剂气体浓度调节；反馈系统则负责对气体浓度进行测量；气路系统则在原有基础上添加活性炭装置，降低无关因素干扰．装置改进之后，不同气路切换时间为75.2 ms，比原装置减少了1 s，有效提高刺激精度．实验结果显示，气体浓度调节前，300 s内乙醇、吡啶、乙酸戊酯嗅剂气体浓度分别下降6.7%、71.4%、79.2%，嗅剂气体浓度短时间内发生较大改变．加入气体浓度调节功能后，当气体浓度下降至目标浓度的90%时，可通过调节气泵电压改变嗅剂气流与空气气流比例，从而调节嗅剂气体浓度至目标值，其中吡啶、乙酸戊酯用时13 s．

Optimal Design for Quantification of Gas Concentration Based Olfactory Stimulator

The existing olfactory stimulator based on magnetic resonance measurement can provide different concentration of olfactory stimulation by adjusting the concentration of olfactory liquid.However,with the progress of the experiment,it is difficult to ensure the concentration stability of odorant gas delivered to the nasal cavity,due to the odorant volatilization and the change of experimental environments(temperature,humidity,air flow),thus affecting the experimental accuracy.In this research,we improved the olfactory stimulation device previously developed by our laboratory to achieve accurate quantification of gas concentration.The improved olfactory stimulator mainly consists of three parts:control system,feedback system and pneumatic system.The control system is mainly use to control gas delivery and adjust concentration of olfactory gas.The feedback system is responsible for measuring the gas concentration.In the pneumatic system,an activated carbon device is added to the original foundation to reduce interference of irrelevant factors.After the improvement,the switching response time between different pneumatic branches reached to 75.2 ms,which is nearly 1 s less than the original device,and effectively improves the accuracy of stimulus.The experimental results show that the olfactory gas concentration of ethanol,pyridine and amyl acetate decrease by 6.7%,71.4%,and 79.2% respectively,within 300 s before adjusting the gas concentration.The odorant gas concentration changes significantly in a short time.The gas concentration regulation function can be realized by adjusting the voltage of air pump of the feedback system to change the ratio of odorant airflow and pure airflow.When the gas concentration drops to 90% of the target value,it took 13 s to adjust the odorant gas concentration to the target value for pyridine and amyl acetate.