Design and implementation of collagen-based capacitive relative humidity sensors

Shapardanis, Steven; Hudspeth, Mathew A.; Kaya, Tolga

doi:10.1109/icsens.2013.6688506

Cited by 1 publication

(2 citation statements)

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“…13 The hysteresis due to adsorption and desorption can be accounted for by examining the temperature shifts during the experiment in Figure 3(b). A temperature cross-sensitivity will account for different capacitance levels at the same humidity for different temperatures.…”

Section: Discussionmentioning

confidence: 99%

“…Previous work has shown that varying the gelatin-to-water concentration over a range of spin speeds from 1000 to 5000 rpm (revolutions per minute) will produce gelatin thin films between 100 and 1200 nm thick. 13 The gelatin sensing film was applied using a Laurell spin coater at 2000 rpm for 20 seconds to create a 300 nm thick film on a 100 nm copper thin film which was deposited onto the gelatin film using metal evaporation. Thicker gelatin film as chosen to eliminate the fringing field effects through the air.…”

Section: Sensor Fabricationmentioning

confidence: 99%

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Gelatin as a new humidity sensing material: Characterization and limitations

2014

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The goal of this work is to assert the utility of collagen and its denatured counterpart gelatin as cost-effective alternatives to existing sensing layers comprised of polymers. Rather than producing a material that will need to be discarded or recycled, collagen, as a by-product of the meat and leather industry, could be repurposed. This work examines the feasibility of using collagen as a sensing layer. Planar electrodes were patterned with lift-off process to work with the natural characteristics of gelatin by utilizing metal vapor deposition, spin coating, and photolithography. Characterization methods have also been optimized through the creation of specialized humidity chambers that isolate specific characteristics such as response time, accuracy, and hysteresis. Collagen-based sensors are found to have a sensitivity to moisture in the range of 0.065 pF/%RH. Diffusion characteristics were also analyzed with the diffusion coefficient found to be 2.5 × 10−5 cm2/s. Absorption and desorption times were found to be 20 seconds and 8 seconds, respectively. Hysteresis present in the data is attributed to temperature cross-sensitivity. Ultimately, the utility of collagen as a dielectric sensing material is, in part, due to its fibrous macrostructures as well its hydrophilic sites along the peptide chains. Gelatin was patterned between and below interdigitated copper electrodes and tested as a relative humidity sensor. This work shows that gelatin, which is inexpensive, widely available, and easy to process, can be an effective dielectric sensing polymer for capacitive-type relative humidity sensors.

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Section: Discussionmentioning

confidence: 99%

Section: Sensor Fabricationmentioning

confidence: 99%