20.4 MEMS-Free 4096-Pixel CMOS E-Nose Gas-Sensor Array with Molecular-Selective Metal-Organic-Framework Sensing and In-Pixel Thermodynamic Modulation for Fast Sensor Regeneration

Accurate and real-time sensing of gas molecule species and concentrations is critical for a myriad of applications, including environmental protection, industry automation, public health monitoring, and bio-/chemical-security surveillance. For example, gas sensing in large chemical plants is crucial for safety and production efficiency, with ammonia (NH3) being particularly important due to its extensive use [1]. Electronic noses (e-noses) consist of a chemical sensor array with surface recognition modules for capturing specific or multi-species gas molecules followed by electronic signal acquisition and processing [2]. Despite decades of exploration [3]–[5], the development of e-noses is still in its early stages, and existing e-noses continue to face major challenges as: (1) limited selectivity on target molecules (2) poor sensor regeneration due to slow and incomplete gas desorption process, which can result in sensing memory effect, i.e., affecting low-trace gas detection due to prior exposure to high concentrations, (3) a small number of sensing nodes instead of a large array, also lacking in-pixel signal processing and data digitization [6], [7]. To address these issues, we present a monolithically integrated molecular specific metal-organic-frameworks (MOFs) CMOS e-nose sensor array with in-pixel fast capacitance-gas interfacing, readout, and data digitization with local temperature regulation and sensing. For demonstration, NiNi-Pyz MOFs have been employed to achieve NH3 specificity. In particular, the in-pixel temperature regulation can modulate the thermodynamic of NH3 adsorption and desorption at the sensor interfaces, significantly improving the sensitivity and allowing rapid sensor regeneration.