Sukhwinder K. Bhullar

Design and fabrication of auxetic stretchable force sensor for hand rehabilitation

Using a melt electrospinning technique, stretchable force sensors were designed for use in an application of hand rehabilitation. The main purpose of this study was to verify that the use of auxetic sensors improved hand rehabilitation practices when compared to their absence. For this study, novel stretchable poly (-caprolactone) (PCL) force sensors were fabricated into the following formations: auxetic microfiber sheets (AMSs), auxetic solid sheets (ASSs), microfiber sheets (MSs), and solid sheets (SSs). A femtosecond laser device was used to make an auxetic structure in the MSs and SSs. Subsequently, these sensors were coated with gold particles to make them conductive for the electrical current resistance assays. Through the cycles of applied stress and strain, auxetic structures were able to retain their original shape once these forces have been dissipated. This stretchable sensor could potentially measure applied external loads, resistance, and strain and could also be attachable to a desired substrate. In order to verify the workability and practicality of our designed sensors, we have attempted to use the sensors on a human hand. The AMS sensor had the highest sensitivity on measuring force and resistance among the four types of sensors. To our knowledge, this is the first study to form a stretchable force sensor using a melt electrospinning technique.

Design and fabrication of auxetic PCL nanofiber membranes for biomedical applications

The main objective of this study was to fabricate poly (ε-caprolactone) (PCL)-based auxetic nanofiber membranes and characterize them for their mechanical and physicochemical properties. As a first step, the PCL nanofibers were fabricated by electrospinning with two different thicknesses of 40μm (called PCL thin membrane) and 180μm (called PCL thick membrane). In the second step, they were tailored into auxetic patterns using femtosecond laser cut technique. The physicochemical and mechanical properties of the auxetic nanofiber membranes were studied and compared with the conventional electrospun PCL nanofibers (non-auxetic nanofiber membranes) as a control. The results showed that there were no significant changes observed among them in terms of their chemical functionality and thermal property. However, there was a notable difference observed in the mechanical properties. For instance, the thin auxetic nanofiber membrane showed the magnitude of elongation almost ten times higher than the control, which clearly demonstrates the high flexibility of auxetic nanofiber membranes. This is because that the auxetic nanofiber membranes have lesser rigidity than the control nanofibers under the same load which could be due to the rotational motion of the auxetic structures. The major finding of this study is that the auxetic PCL nanofiber membranes are highly flexible (10-fold higher elongation capacity than the conventional PCL nanofibers) and have tunable mechanical properties. Therefore, the auxetic PCL nanofiber membranes may serve as a potent material in various biomedical applications, in particular, tissue engineering where scaffolds with mechanical cues play a major role.

Fabrication and Characterization of Nonwoven Auxetic Polymer Stent

Synthetic biomaterials have better controlled physical and mechanical properties and can be used to tailor both soft and hard tissues. A tiny, expandable mesh tubes called stents keep blood vessels open and allow blood flow and treat blockage to improve quality of patient’s life. The main focus of this work is to (i) fabricate a polymeric sheet of melt electrospun polycaprolactone microfibers; (ii) tailor auxetic geometry by micromachining on polycaprolactone microfiber and polycaprolactone sheet; (iii) fabricate a cylindrical tube to make auxetic stents. Final results for mechanical characterization and performance analysis of auxetic polymer stents are discussed. GRAPHICAL ABSTRACT

Development of Bioactive Packaging Structure Using Melt Electrospinning

AbstractRecent research attention is shifting towards the use of bioactive antimicrobial and/or antioxidant packaging materials and their fabrication with non-toxic techniques. The process of melt electrospinning produce fibers from polymer melt without any solution hence environmentally friendly because use of toxic solvents can be avoided. The objectives of this study were fabrication of biodegradable polymeric microfibrous structure using melt electrospinning and characterization of the effect of plant based natural extract on fabricated structure. We found that incorporation of this structure with natural extract provide sufficient support for bioactive compounds without changing thermal stability, physical properties and amorphous phase and also increase the antimicrobial efficacy. Moreover, homogeneously dispersion and good interaction of polymer and natural plant based extract demonstrating the potential of such polymer blend as a bioactive antimicrobial material for packaging industry including especially food and healthcare.

Antibacterial activity of combination of synthetic and biopolymer non-woven structures.

Abstract Background: Fibrous structures and synthetic polymer blends offer potential usages in making biomedical devices, textiles used in medical practices, food packaging, tissue engineering, environmental applications and biomedical arena. These products are also excellent candidates for building scaffolds to grow stem cells for implantation, to make tissue engineering grafts, to make stents to open up blood vessels caused by atherosclerosis or narrowed by blood clots, for drug delivery systems for micro- to nano-medicines, for transdermal patches, and for healing of wounds and burn care. The current study was designed to evaluate the antimicrobial activity of woven and non-woven forms of nano- and macro-scale blended polymers having biocompatible and biodegradable characteristics. Methods: The antimicrobial activity of non-woven fibrous structures created with the combination of synthetic and biopolymer was assessed using Gram-negative, Gram-positive bacteria, such as Staphylococcus aureus, Proteus vulgaris, Escherichia coli and Enterobacter aerogenes using pour plate method. Structural evaluation of the fabricated samples was performed by Fourier transform infrared spectroscopy. Results: Broad spectrum antibacterial activities were found from the tested materials consisting of polyvinyl alcohol (PVA) with chitosan and nylon-6 combined with chitosan and formic acid. Conclusions: The combination of PVA with chitosan was more bactericidal or bacteriostatic than that of nylon-6 combined with chitosan and formic acid. PVA combination with chitosan appears to be a broad-spectrum antimicrobial agent.

Health Benefits of Bovine Colostrum in Children and Adults

Abstract Colostrum is a thick, sticky, yellowish mammary secretion that all mammals provide to their newborns during the first 24–48 hours after delivery. Human newborns receive colostrum from their mothers during the first few hours after birth, and this “Elixir of Life” not only provides naturally produced nutrients and antibodies in a highly concentrated low volume but also creates the foundation of life-long immunity. Colostrum is rich in immunoglobulins and lactoferrin, growth, and antimicrobial factors, all of which promote tissue growth and maturation of digestive tract and immune function in neonatal animals and humans. The immunoglobulins present in colostrum invoke antimicrobial activity by forming a chelated complex with bacterial and viral antigens. It has been reported that constituents from bovine colostrum (BC) are 100-fold to 1000-fold more potent than human colostrum. This means that if the human neonates do not get enough maternal colostrum to build their passive immunity, then they can rely on cow or buffalo colostrum to gain health benefits. There is emerging evidence that BC may be one of the promising nutraceuticals which can prevent or mitigate various diseases in newborns and adults. Immunity-related disorders are one of the leading causes of morbidity in the world. BC has the potential to enhance the immune function and well-being of healthy persons and patients. The immunoglobulins and lactoferrin present in colostrum are known to build natural immunity in newborns, which helps to reduce the mortality rate in this population. Lactoferrin is involved in several physiological and protective functions, including regulation of iron absorption in the bowel, antioxidant, anticancer, antiinflammatory, and antimicrobial activities. As opposed to milk, BC has less lactose, and therefore may be suitable for patients suffering from lactose intolerance. A limited number of human and animal studies done with colostrum supplements are indicative of future prospects for helping in curing diseases like AIDS, cardiovascular and gastrointestinal disorders, infectious diseases, wound healing, and certain cancers. Since colostrum has several naturally occurring important nutritional components, well-designed, double-blind, placebo-controlled studies with colostrum products are needed to widen their therapeutic role in children and adults. It indeed seems to be a treasure trove that, if tapped, could eventually reveal many health benefits and cost-effective cures in humans. This review summarizes the comparative amounts of fat, proteins, lactose, vitamins, and minerals present in human, cow, buffalo, and goat colostrum. The major objectives of this review are to create awareness about the nutraceutical properties of colostrum, and to discuss the various ongoing alternative treatments of colostrum and its active ingredients as well as to address colostrum’s future nutraceutical and therapeutic intervention in humans.