@article{prasetya2024investigation,

title = {Investigation of the Free-Base Zr-Porphyrin MOFs as Humidity Sensors for an Indoor Setting},

author = {Nicholaus Prasetya and Salih Okur},

url = {https://chemrxiv.org/engage/chemrxiv/article-details/6608e3c466c138172950e040},

doi = {https://doi.org/10.26434/chemrxiv-2024-1jwr7},

year  = {2024},

date = {2024-04-01},

urldate = {2024-04-01},

abstract = {Maintaining optimal relative humidity is paramount for human comfort. Therefore, the utilization of quartz crystal microbalance (QCM) as a humidity sensor platform holds significant promise due to its cost-effectiveness and high sensitivity. This study explores the efficacy of three free-base Zr porphyrin metal-organic frameworks (MOFs) - namely MOF-525, MOF-545, and NU-902 - as sensitive materials for QCM-based humidity sensors. Our extended experimental findings reveal that these materials exhibit notable sensitivity, particularly within relative humidity ranges of 40% to 100%. However, we observe potential irreversible adsorption sites within the MOF-545 framework, hindering its ability to revert to its initial state after prolonged exposure. In light of this observation, we conduct periodic cycling experiments at relative humidity levels of 40-70% to evaluate the measurement repeatability and feasibility of these sensors for indoor applications. Interestingly, the periodic cycling study demonstrates that MOF-545 shows promising repeatability, positioning it as a strong contender for indoor humidity sensing. In contrast, MOF-525 may necessitate extended desorption time, and NU-902 displays diminished sensitivity at low relative humidity levels. Nevertheless, a preliminary treatment of the MOF-545 QCM sensor may be necessary to address irreversible adsorption sites and uphold measurement repeatability, as only reversible adsorption sites are currently accessible. This study underscores the potential of MOF-based QCM sensors for effective humidity monitoring in indoor environments, thus facilitating improved comfort and environmental control.},

keywords = {Adsorption, humidity, openQCM, QCM, QCM sensor, Zr-porphyrin metal organic frameworks},

pubstate = {published},

tppubtype = {article}

}

@article{jang2022direct,

title = {Direct and controlled device integration of graphene oxide on Quartz Crystal Microbalance via electrospray deposition for stable humidity sensing},

author = {Il Ryu Jang and Soon In Jung and Jeonhyeong Park and Chaehyun Ryu and Inyong Park and Sang Bok Kim and Hoe Joon Kim},

url = {https://www.sciencedirect.com/science/article/pii/S0272884221037706},

year  = {2022},

date = {2022-01-01},

urldate = {2022-01-01},

journal = {Ceramics International},

volume = {48},

number = {6},

pages = {8004--8011},

publisher = {Elsevier},

abstract = {Integration of advanced and functional materials onto conventional sensing platforms can improve the device performances and even discover new applications. For piezoelectric resonant sensors, an addition of sensing materials can induce damping and hinder a stable device operation. Hence, the development of efficient method for materials integration is important to ensure high-performance and reliable sensor operation. This work presents a direct and precisely controlled integration of graphene oxide (GO) using the electrospray deposition (ESD) onto a 10 MHz Quartz Crystal Microbalance (QCM) for humidity sensing. The proposed ESD method achieves a high mass resolution of a few nanograms. Moreover, the GO uniformly coats across the sensing electrode region as it acts as a ground electrode during ESD. The proposed ESD method also works for a wide range of nanomaterials, such as carbon nanotubes, tin oxide, and silicon carbide micro-and nano-powders. Compared to the conventional drop-casting and dip coating approaches, our method ensures minimal GO agglomeration, resulting in a stable QCM-oscillator operation in a wide range of relative humidity from 11% to 97%. The measurement sensitivity increases with an amount of GO, but less GO results in better noise and detection limit performances. The results shed light on the importance of selecting an optimal amount of sensing materials for stable sensor operations.},

keywords = {electrospray deposition, humidity},

pubstate = {published},

tppubtype = {article}

}