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A Micromachined Picocalorimeter Sensor for Liquid Samples with Application to Chemical Reactions and Biochemistry
Advanced Science ( IF 14.3 ) Pub Date : 2021-01-12 , DOI: 10.1002/advs.202003415
Jinhye Bae 1 , Juanjuan Zheng 2 , Haitao Zhang 2 , Peter J Foster 3 , Daniel J Needleman 4, 5 , Joost J Vlassak 2
Affiliation  

Calorimetry has long been used to probe the physical state of a system by measuring the heat exchanged with the environment as a result of chemical reactions or phase transitions. Application of calorimetry to microscale biological samples, however, is hampered by insufficient sensitivity and the difficulty of handling liquid samples at this scale. Here, a micromachined calorimeter sensor that is capable of resolving picowatt levels of power is described. The sensor consists of low‐noise thermopiles on a thin silicon nitride membrane that allow direct differential temperature measurements between a sample and four coplanar references, which significantly reduces thermal drift. The partial pressure of water in the ambient around the sample is maintained at saturation level using a small hydrogel‐lined enclosure. The materials used in the sensor and its geometry are optimized to minimize the noise equivalent power generated by the sensor in response to the temperature field that develops around a typical sample. The experimental response of the sensor is characterized as a function of thermopile dimensions and sample volume, and its capability is demonstrated by measuring the heat dissipated during an enzymatically catalyzed biochemical reaction in a microliter‐sized liquid droplet. The sensor offers particular promise for quantitative measurements on biological systems.

中文翻译:


用于液体样品的微机械皮热量计传感器及其在化学反应和生物化学中的应用



量热法长期以来一直用于通过测量化学反应或相变与环境交换的热量来探测系统的物理状态。然而,由于灵敏度不足以及处理这种规模的液体样品的困难,量热法在微型生物样品中的应用受到阻碍。这里描述了一种能够解析皮瓦级功率的微机械热量计传感器。该传感器由氮化硅薄膜上的低噪声热电堆组成,可以直接测量样品和四个共面参考之间的温差,从而显着减少热漂移。使用小型水凝胶内衬外壳将样品周围环境中的水分压保持在饱和水平。传感器中使用的材料及其几何形状经过优化,可最大程度地减少传感器响应典型样品周围形成的温度场而产生的噪声等效功率。该传感器的实验响应被表征为热电堆尺寸和样品体积的函数,并且通过测量微升大小的液滴中酶催化生化反应期间耗散的热量来证明其能力。该传感器为生物系统的定量测量提供了特殊的前景。
更新日期:2021-03-03
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