3D Printable Sensorized Soft Gelatin Hydrogel for Multi-Material Soft Structures

Abstract

The ability to 3D print soft materials with integrated strain sensors enables significant flexibility for the design and fabrication of soft robots. Hydrogels provide an interesting alternative to traditional soft robot materials, allowing for more varied fabrication techniques. In this work, we investigate the 3D printing of a gelatin-glycerol hydrogel, where transglutaminase is used to catalyse the crosslinking of the hydrogel such that its material properties can be controlled for 3D printing. By including electron-conductive elements (aqueous carbon black) in the hydrogel we can create highly flexible and linear soft strain sensors. We present a first investigation into adapting a desktop 3D printer and optimizing its control parameters to fabricate sensorized 2D and 3D structures which can undergo >300% strain and show a response to strain which is highly linear and synchronous. To demonstrate the capabilities of this material and fabrication approach, we produce some example 2D and 3D structures and show their sensing capabilities.

Edible Origami Actuators Using Gelatin-Based Bioplastics

“…Custom molds (Figure b) combined with UV-laser cutting can create gelapin bioplastics with over 100 creases per 3 cm 2 . Compared to alternative works with individual cm-scale folds, this improved feature density can enable smaller actuator designs with higher degrees of freedom and articulation. − Figure c–e shows the example of bioplastic origami products and their deployment under 80% RH. A 150 μm-thick gelapin substrate containing 37.5 wt % glycerol and 100 mol % genipin crosslinking was used to create the origami.…”

Sustainable Robots 4D Printing

“…Utilizing the absorbent properties of bio‐polymers such as gelatin or alginate, these lines of research were able to create sensorized hydrogels. Hardman et al [ 143 ] used the FFF method to fabricate a biodegradable, biocompatible soft sensor employing gelatin‐glycerol hydrogel. They presented the first investigation into adapting a desktop 3D printer and optimizing its control parameters to fabricate sensorized 2D and 3D structures that can withstand >300% strain and exhibit a highly linear and synchronous response to strain.…”

“…Alginate/methylcellulose (Alg/MC), [ 62 ] PLA, [ 72,80,95,141 ] poly(ethylene adipate) (PEA), [ 95 ] polylactide‐co‐trimethylene carbonate (PLMC), [ 64 ] carrageenan‐based nanocomposites, [ 152,153 ] multi‐walled carbon nanotubes (MWCNTs), [ 141,143 ] chitosan hydrogels, [ 67 ] PCL, [ 63,68,72 ] sodium alginate, [ 68 ] bio‐polyurethane (BPU), [ 114 ] carboxymethyl chitosan (CMCS), [ 114 ] protein‐based hydrogels, [ 70 ] propylene glycol di acetate (PGDA), [ 74 ] cellulose‐based biopolymers, [ 115,136,157 ] carboxymethyl cellulose (CMC), [ 114,134 ] gelatin hydrogels, [ 146 ] and poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) [ 148 ] are among biodegradable materials used to make appropriate ink for DIW technique.…”

“…Similarly, biodegradability in flexible sensors offers numerous applications in diverse areas, such as E‐tongues for soil quality sensing in agriculture, [ 135–138 ] biomedicine, [ 62,66,77,139,140 ] liquid sensing, [ 137,141 ] humidity sensing, [ 136,142 ] strain sensing, [ 140,143–151 ] force sensing, [ 77,139,152–154 ] magnetic field sensing, [ 62 ] gas sensing, [ 138,155 ] pH sensing, [ 66 ] temperature sensing, [ 156 ] ion sensing, [ 66 ] wearable soft sensors, [ 95,111,114,118,143–146,149,151,157 ] waveguide sensors, [ 98 ] soft sustainable electronics, [ 95,109,111,118,139,140,144–149,151–153 ] human motion sensing for healthcare monitoring, [ 118,145,146,157,158 ] environment monitoring, [ 136 ] bioelectrodes, [ 145,146 ] touch sensors, [ 109 ] food quality sensing for smart packaging, [ 138,155 ] antennas, [ 156,159 ] and structures health monitoring. [ 142 ] Figure depicts a brief evolution of additively manufactured BSSA, as well as the ecofriendly material used in their construction.…”

Resveratrol Triggered the Quick Self-Assembly of Gallic Acid into Therapeutic Hydrogels for Healing of Bacterially Infected Wounds

“…Hydrogels are soft materials consisting of a three-dimensional (3D) hydrophilic polymer network that can swell in water or biological fluids. − Because the hydrogel has good water retention properties, it can absorb wound exudate, thereby promoting the infiltration of dermal and epidermal cells and finally re-epithelializing the wound . Also, most hydrogels have the merits of good biocompatibility and continuous degradation .…”