Direct ink write multi-material printing of PDMS-BTO composites with MWCNT electrodes for flexible force sensors

Abstract

With recent advances of additive manufacturing (AM) technology, direct ink write (DIW) printing has allowed to incorporate multi-material printing of various materials with freedom of design and complex geometric shapes to complete functional sensors in a one-step fabrication. This paper introduces the use of DIW 3D printing of polydimethylsiloxane (PDMS) with barium titanate (BTO) filler as stretchable composites with tunable piezoelectric properties that can be used for force sensors applications. To improve the bonding between stretchable piezoelectric composites and electrodes, multi-walled carbon nanotubes (MWCNT) was included in the fabrication of electrodes at a fixed ratio of 11 wt. %. The alignment of the BTO dipoles was achieved through corona poling method, which applies an electric charge on the surface layer of the functional material, aligning the dipoles in the desired direction and thus gaining the piezoelectricity. Different BTO mixing ratios (10-50 wt. %) were evaluated in order to obtain tunable piezoelectric properties and compare the sensitivity with respect their elastic properties. Tensile testing and piezoelectric testing were carried out to characterize mechanical and piezoelectric properties. Results showed that fabricated PDMS with 50 wt. % BTO gave the highest piezoelectric coefficient (d33) of 11.5 pC/N and with an output voltage of 385 mV under compression loading of >200 lbF. This demonstrates feasibility of using multi-material DIW printing to fabricate piezoelectric force sensors with integrated electrodes in one-step without compromising the flexibility of the material.

Low-temperature processing of screen-printed piezoelectric KNbO3 with integration onto biodegradable paper substrates

“…Recent low-temperature approaches for printing piezoelectric materials involve polymer ceramic composites (typically nonbiodegradable polyvinylidene fluoride (PVDF) or polydimethylsiloxane (PDMS) embedded with ferroelectric particles) 19,20 . This approach removes the sintering step at the cost of a significant reduction in piezoelectric performance relative to bulk literature values for conventional processes [21][22][23] .…”

Polydimethylsiloxane/carboxylated hydroxylated multiwalled carbon nanotubes/polyimide composite membrane wearable flexible piezoresistive tactile sensor device with microsphere array

“…Hydroxylated multiwalled carbon nanotubes (carboxylated MWCNT) has the advantages of high conductivity, high aspect ratio, high strength, and high stability, the adaption of carboxylated MWCNT as the conductive filler of force sensitive composites can reduce the impact on the original mechanical properties of polymers, and the size of carboxylated MWCNT particles is usually at the nano level, which can significantly improve the sensitivity of conductive composites. In addition, carboxylated MWCNT has high strength and stable properties, and will not be damaged under the repeated external forces 12,13 . Polydimethylsiloxane (PDMS) material has excellent biocompatibility and stability that is the most ideal material for preparing flexible substrate 14 .…”

“…In addition, carboxylated MWCNT has high strength and stable properties, and will not be damaged under the repeated external forces. 12,13 Polydimethylsiloxane (PDMS) material has excellent biocompatibility and stability that is the most ideal material for preparing flexible substrate. 14 Maity et al 15 have prepared the wearable human motion sensor and humidity monitoring sensor by spraying carboxylated MWCNT on the textile layer by layer.…”

Synergy of PMN-PT with piezoelectric polymer using sugar casting method for sensing applications

“…While direct fabrication of piezoelectric foams, for example by mechanical frothing of a ceramic suspension, is simple and low cost the resultant structures remain brittle and will still require shaping, drying and sintering [2]. Composites created by a piezoceramic nanoparticle inclusion are attractive to low frequency applications such as energy harvesting [3] and low frequency hydrophones [4] but have far lower piezoelectric modulus than bulk ceramic. Modification of PZT nanoparticles with surfactants has shown increases in the d 33 measure to 52 pC/N with relatively low particle loading within a polyethalene glycol diacrylate (PEGDA) resin (16% wt/wt) [5] with the same group later showing large gains in the compliance of the piezoelectric materials by adopting a 3D printed lattice structure [6].…”