Smart and intelligent materials provide direct or indirect solutions for many
of the current/existing problems. Studies in this line have been in progress since few
decades developing multifunctional materials, smart systems etc., for specific
applications. Though many smart materials were developed, not much of them are
compatible as implants in human body. One such material that possesses the inherent
requirements attuned with human body is ‘hydrogel’. Like other smart materials, gels
can also be intelligent in their responses to the environments they are exposed to, or on
influence of any induced stimuli. Many such smart gels are explored by various
industries and are used for applications such as drug delivery systems, cancer therapy,
tissue engineering and organ printing, but a comprehensive understanding with
properties, and their mechanisms regarding their functionality and usage are meagre.
This work consolidates and details the classification of gels and elaborates the various
stimuli to which gels respond and the mechanisms involved. This article also explores
the possibilities, prospects of 3D-printing of smart gels in biomedical field and has
listed the possible applications of hydrogels.
Keywords: 4D printing, Additive manufacturing, Artificial lens, Artificial muscles, Bimodal, Biochemical, Cross-linking, Drug delivery, Hydrogels, Hydrophilic, Hydrophobic, Organ printing, Self-healing, Shape memory hydrogels, Smart gels, Spinodal, Stimuli responsive, Superporous, Supramolecular, Tissue engineering.