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Highly elastic conductive polymeric MEMS

View Article: PubMed Central - PubMed

ABSTRACT

Polymeric structures with integrated, functional microelectrical mechanical systems (MEMS) elements are increasingly important in various applications such as biomedical systems or wearable smart devices. These applications require highly flexible and elastic polymers with good conductivity, which can be embedded into a matrix that undergoes large deformations. Conductive polydimethylsiloxane (PDMS) is a suitable candidate but is still challenging to fabricate. Conductivity is achieved by filling a nonconductive PDMS matrix with conductive particles. In this work, we present an approach that uses new mixing techniques to fabricate conductive PDMS with different fillers such as carbon black, silver particles, and multiwalled carbon nanotubes. Additionally, the electrical properties of all three composites are examined under continuous mechanical stress. Furthermore, we present a novel, low-cost, simple three-step molding process that transfers a micro patterned silicon master into a polystyrene (PS) polytetrafluoroethylene (PTFE) replica with improved release features. This PS/PTFE mold is used for subsequent structuring of conductive PDMS with high accuracy. The non sticking characteristics enable the fabrication of delicate structures using a very soft PDMS, which is usually hard to release from conventional molds. Moreover, the process can also be applied to polyurethanes and various other material combinations.

No MeSH data available.


Resistance-strain measurement for a 200 μm thin layer of MWCNT-PDMS. Different elongation cycles are shown, starting with cycle 2 after the first preload cycle.
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Figure 6: Resistance-strain measurement for a 200 μm thin layer of MWCNT-PDMS. Different elongation cycles are shown, starting with cycle 2 after the first preload cycle.

Mentions: MWCNT-PDMS. Figure 6 displays the measurements taken for MWCNT-PDMS. Starting with a base resistance of , the resistance again increases after the first preload cycle to at 0% strain. The base conductivity measured over a distance of 34 mm is 9.0 Sm−1. The material shows a similar global behavior to C-PDMS regarding the decrease in resistance and hysteresis with each subsequent cycle. After 2500 cycles, the resistance at 0% strain decreased to , thus yielding to a decrease of 13.6 %, compared to the resistance after preloading. However, MWCNT-PDMS shows a linear behavior only in the low strain region stretching from approximately 2 to 10% strain, which limits its application to resistive strain gauge sensors. A similar curve shape for MWCNT-PDMS regarding the hysteresis was also found by [19].


Highly elastic conductive polymeric MEMS
Resistance-strain measurement for a 200 μm thin layer of MWCNT-PDMS. Different elongation cycles are shown, starting with cycle 2 after the first preload cycle.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036488&req=5

Figure 6: Resistance-strain measurement for a 200 μm thin layer of MWCNT-PDMS. Different elongation cycles are shown, starting with cycle 2 after the first preload cycle.
Mentions: MWCNT-PDMS. Figure 6 displays the measurements taken for MWCNT-PDMS. Starting with a base resistance of , the resistance again increases after the first preload cycle to at 0% strain. The base conductivity measured over a distance of 34 mm is 9.0 Sm−1. The material shows a similar global behavior to C-PDMS regarding the decrease in resistance and hysteresis with each subsequent cycle. After 2500 cycles, the resistance at 0% strain decreased to , thus yielding to a decrease of 13.6 %, compared to the resistance after preloading. However, MWCNT-PDMS shows a linear behavior only in the low strain region stretching from approximately 2 to 10% strain, which limits its application to resistive strain gauge sensors. A similar curve shape for MWCNT-PDMS regarding the hysteresis was also found by [19].

View Article: PubMed Central - PubMed

ABSTRACT

Polymeric structures with integrated, functional microelectrical mechanical systems (MEMS) elements are increasingly important in various applications such as biomedical systems or wearable smart devices. These applications require highly flexible and elastic polymers with good conductivity, which can be embedded into a matrix that undergoes large deformations. Conductive polydimethylsiloxane (PDMS) is a suitable candidate but is still challenging to fabricate. Conductivity is achieved by filling a nonconductive PDMS matrix with conductive particles. In this work, we present an approach that uses new mixing techniques to fabricate conductive PDMS with different fillers such as carbon black, silver particles, and multiwalled carbon nanotubes. Additionally, the electrical properties of all three composites are examined under continuous mechanical stress. Furthermore, we present a novel, low-cost, simple three-step molding process that transfers a micro patterned silicon master into a polystyrene (PS) polytetrafluoroethylene (PTFE) replica with improved release features. This PS/PTFE mold is used for subsequent structuring of conductive PDMS with high accuracy. The non sticking characteristics enable the fabrication of delicate structures using a very soft PDMS, which is usually hard to release from conventional molds. Moreover, the process can also be applied to polyurethanes and various other material combinations.

No MeSH data available.