Integrated temperature humidity sensor

Structure of the integrated temperature humidity sensors. Top view (above) and cross sectional view at a-b (below). 

The fabrication of humidity sensors on silicon chips has recently become possible using 1C. production technology [37, 49], This realizes a small, low cost humidity sensor, and makes it possible to integrate the humidity sensor with other sensors or signal-handling circuitry on the same chip. A new integrated temperature and humidity sensor developed by Yamamoto et al., consists of a polymer capacitor on the p-n diode of a temperature sensor [50] as illustrated in Figure 20-33. A thin film of polyimide is used as the moisture-sensitive material... 

Moser Y, Gijs MAM (2007) Miniatnrized flexible temperatnre sensor. J Microelectromech Syst 16(6) 1349-1354 Oprea A, Barsan N, Weimar U, Combat J, Briand D, de Rooij NF (2007) Integrated temperature, humidity and gas sensors on flexible substrates for low-power applications. In Proceedings IEEE sensors conference, Atlanta, USA, Oct 28-31, pp 158-161... 

The features of the monoHthic integrated sensor systems have not yet been fully exploited. The almost linear relationship between input reference voltage and microhotplate temperature renders the systems suitable for applying any temperature modulation protocol. Due their compatibility with other CMOS-based chemical sensors the microhotplates can be also combined with, e.g., polymer-based mass sensitive, calorimetric or capacitive sensors. The co-integration with such sensors can help to alleviate problems resulting from cross-sensitivities of tin-oxide based sensors to, e.g., volatile compounds such as hydrocarbons. A well-known problem is the crosssensitivity of tin oxide to humidity or ethanol. The co-integration of a capacitive sensor, which does not show any sensitivity to CO, could help to independently assess humidity changes. 

Temperature and/or humidity mapping of the chamber at the required set point is an integral part of OQ tests. Mapping includes the placement of temperature and humidity sensors at various locations within the chamber to demonstrate that the temperature and/or humidity will be consistent throughout different areas of the chamber under ideal conditions. Temperature and humidity readings should be obtained over a defined period, typically, a minimum of 24 h. 

Okamura K, Ishiji T, Iwaki M, Suzuki Y, Takahashi K (2007) Electrochemical gas sensor using a novel gas permeable electrode modified by ion implanfafion. Surf Coat Technol 201 8116-8119 Oprea A, Courbat J, Barsan N, Briand D, de Rooij NF, Weimar U (2009) Temperature, humidity and gas sensors integrated on plastic foil for low power applications. Sens Actuators B 140 227-232 Park CO, Akbar SA (2003) Ceramics for chemical sensing. J Mater Sd 38 4611 637... 

Polpmides have excellent thermal stability, solvent resistance, radiation resistance, wear resistance, hydrolytic stability, low dielectric constant, high mechanical properties, good chemical resistance and a low dielectric constant. Due to these superior properties, the application field of polyimide has generally been enlarged from printed circuit boards and electrical insulation layers in microelectronics to functional layers of humidity sensors, shielding layers for sensor surfaces and novel platforms for thermal sensor devices, temperature sensor arrays, micro-hotplates integrated into gas sensors and biosensors. 

Jimenez, L., Rocha, A.M., Aranberri, I., Covas, J.A., Catarino, A.P., 2009. Electrically conductive monofilaments for smart textiles. Advances in Science and Technology 60, 58—63. Ataman, C., Kinkeldei, T., Vasquez-Quintero, A., Molina-Lopez, E., Courbat, J., Cherenack, K., Briand, D., Troster, G., de Rooij, N.F., 2011. Humidity and temperature sensors on plastic foil for textile integration. Procedia Engineering 25, 136—139. 

Kinkeldei, T., Zysset, C., Cherenack, K.H., Troster, G., 2011. A textile integrated sensor system for monitoring humidity and temperature. In Sohd-state Sensors, Actuators and Microsystems Conference (TRANSDUCERS), 2011 16th International. IEEE, pp. 1156—1159. 

The ideal sensors to be integrated in an e-nose should fulfill the following criteria [6] high sensitivity toward chemical compounds, that is, similar to that of the human nose (down to 10 g/ml) low sensitivity toward humidity and temperature medium selectivity, they must respond to different compounds present in the headspace of the sample high stability high reproducibility and reliability short reaction and recovery time robust and durable easy calibration easily processable data output small dimensions. 

Kindeldei, T., Mattana, G., Leuenberger, D., et al., 2013. Feasibility ofprinting woven humidity and temperature sensors for integration into electronic textiles. Adv. Sci. Technol. 80, 77-82. 

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