Hostname: page-component-77c89778f8-5wvtr Total loading time: 0 Render date: 2024-07-21T23:25:02.393Z Has data issue: false hasContentIssue false
  • English
  • Français

Collagen as a Humidity Sensing Dielectric Material

Published online by Cambridge University Press:  09 August 2012

Mathew A. Hudspeth  and
Tolga Kaya
Mathew A. Hudspeth
Affiliation:
Science of Advanced Materials, ET 228, Mount Pleasant, MI 48859, U.S.A.
Tolga Kaya*
Affiliation:
Science of Advanced Materials, ET 228, Mount Pleasant, MI 48859, U.S.A. School of Engineering and Technology, ET 130G, Mount Pleasant, MI 48859, U.S.A.
*
*Corresponding Author: kaya2t@cmich.edu
Get access

Abstract

The motivating principle behind this research is the development of small, wearable devices that would use humidity and temperature measurements as metrics for health monitoring. If it is to be useful as a health monitoring tool, the device needs to respond quickly and predictably to changes in humidity. Collagen is shown to be a viable humidity sensing material for use in capacitive relative humidity (RH) sensors. As a natural by-product of meat and leather industries, collagen presents itself as an interesting and inexpensive alternative to polyimide dielectric sensing materials. We used gelatin, a partially hydrolyzed form of collagen, to allow for easier spin coating. We have successfully fabricated devices by depositing a collagen thin film (1.2 μm) via spin coating, followed by Au/Pd electrodes (60 nm) via sputter coating. A plastic mask made from a rapid prototyping machine was used during physical vapor deposition (PVD) to pattern electrodes. This simple method eliminates the need for the use of more complicated photolithography processes. Interdigitated electrodes (rather than parallel plate electrodes) form a 6 mm wide, planar capacitor structure that has little dependence on dielectric thickness and is not affected by dielectric swelling. Initial findings indicate that these devices very closely match the results of the commercial relative humidity sensor used for reference. The capacitance-humidity relationship is shown to be non-linear, with an average change of 3 fF for every 1% change in RH around 60% RH, and an average change of 7 fF for every 1% change in RH around 80% RH. In this work, we present the fabrication and characterization of these novel collagen-based relative humidity sensors.

Keywords

sensordielectric propertiesmicroelectro-mechanical (MEMS)
Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 1427: Symposium B – Heterogeneous Integration Challenges of MEMS, Sensor and CMOS LSI , 2012 , mrss12-1427-b07-04
Copyright
Copyright © Materials Research Society 2012

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

[1] Fenner, R. and Zdankiewicz, E., “Micromachined water vapor sensors: a review of sensing technologies,” IEEE Sensors Journal, vol. 1, no. 4, pp. 309 –317, Dec. 2001.Google Scholar
[2] Kim, Y., Jung, B., Lee, H., Kim, H., Lee, K., and Park, H., “Capacitive humidity sensor design based on anodic aluminum oxide,” Sensors and Actuators B: Chemical, vol. 141, no. 2, pp. 441 – 446, 2009.Google Scholar
[3] Steele, J., Taschuk, M., and Brett, M., “Nanostructured metal oxide thin films for humidity sensors,” IEEE Sensors Journal, vol. 8, no. 8, pp. 1422 –1429, aug. 2008.Google Scholar
[4] Chen, W.-P., Zhao, Z.-G., Liu, X.-W., Zhang, Z.-X., and Suo, C.-G., “A capacitive humidity sensor based on multi-wall carbon nanotubes (mwcnts),” Sensors, vol. 9, no. 9, pp. 7431–7444, 2009.Google Scholar
[5] Lazarus, N. and Fedder, G. K., “Integrated vertical parallel-plate capacitive humidity sensor,” Journal of Micromechanics and Microengineering, vol. 21, no. 6, p. 065028, 2011.Google Scholar
[6] Schubert, P. and Nevin, J., “A polyimide-based capacitive humidity sensor,” IEEE Transactions on Electron Devices, vol. 32, no. 7, pp. 1220 – 1223, Jul. 1985.Google Scholar
[7] Shibata, H., Ito, M., Asakursa, M., and Watanabe, K., “A digital hygrometer using a polyimide film relative humidity sensor,” IEEE Transactions on Instrumentation and Measurement, vol. 45, pp. 564–569, 1996.Google Scholar
[8] Grange, H., Bieth, C., Boucher, H., and Delapiere, G., “A capacitive humidity sensor with every fast response time and very low hysteresis,” Sensors and Actuators, vol. 12, no. 3, pp. 291 – 296, 1987.Google Scholar
[9] Plum, T., Saxena, V., and Jessing, R., “Design of a MEMS capacitive chemical sensor based on polymer swelling,” in WMED 2006 IEEE Workshop on Microelectronics and Electron Devices, 2006.Google Scholar
[10] Kulwicki, B. M., “Humidity sensors,” Journal of the American Ceramic Society, vol. 74, pp. 697–708, 1991.Google Scholar
[11] Lazarus, N., Bedair, S., Lo, C.-C., and Fedder, G., “CMOS-MEMS Capacitive Humidity Sensor,” Journal of Microelectromechanical Systems, vol. 19, no. 1, pp. 183 –191, Feb 2010.Google Scholar
[12] Courbat, J., Kim, Y. B., Briand, D., and de Rooij, N. F., “Inkjet printing on paper for the realization of humidity and temperature sensors,” in Proceedings Solid-State Sensors, Actuators and Microsystems Conference (TRANSDUCERS), vol. 1, 2011, pp. 1356–1359.Google Scholar
[13] GLK Instruments, “Model 3000 Capacitance Meter with Analog Output and USB Port,” http://www.glkinst.com/, January 2012.Google Scholar
[14] OMEGA ENGINEERING Inc, “Portable Temperature and Humidity Data Loggers with Display,” http://www.omega.com/pptst/OM-70_Series.html, January 2012.Google Scholar