A classic challenge in chemical sensing is selectivity. Metal-organic frameworks (MOFs) are an exciting class of materials because they can be tuned for selective chemical adsorption. Adsorption events trigger work-function shifts, which can be detected with a chemical-sensitive field-effect transistor (power ≈microwatts). In this work, several case studies were used towards generalizing the sensing mechanism, ultimately towards our metal-centric hypothesis. HKUST-1 was used as a proof-of-principle humidity sensor. The response is thickness independent, meaning the response is surface localized. ZIF-8 is demonstrated to be an NO2 -sensing material, and the response is dominated by adsorption at metal sites. Finally, MFM-300(In) shows how standard hard-soft acid-base theory can be used to qualitatively predict sensor responses. This paper sets the groundwork for using the tunability of metal-organic frameworks for chemical sensing with distributed, scalable devices.
July 23, 2019
D. W. Gardner, X. Gao, H. M. Fahad, A. T. Yang, S. He, A. Javey, C. Carraro, and R. Maboudian, “Transistor‐Based work‐function measurement of METAL–ORGANIC frameworks for ULTRA‐LOW‐POWER, rationally designed chemical sensors,” Chemistry – A European Journal, vol. 25, no. 57, pp. 13176–13183, 2019.