Piezoelectric “Kumihimo-gumi” sensor fabricated by braiding method using piezoelectric poly-L-lactic acid fiber

We have developed a piezoelectric braided cord consisting of a conducting fiber yarn core, piezoelectric poly-l-lactic acid (PLLA) fiber yarn and a polyethylene terephthalate (PET) middle sheath, and a conducting fiber outer shield (piezoelectric PLLA braided cord). Actually, we made various types of piezoelectric PLLA braided cords using Japanese traditional braiding method called as Kumihimo-gumi in Japanese. Furthermore, by optimization based on the calculation results for each type of piezoelectric PLLA Kumihimo-gumi obtained by the finite element method (FEM), we were able to develop a new type of piezoelectric PLLA braided cord with a sensing function for complex motion (piezoelectric PLLA Kumihimo-gumi). Finally, we developed a new wearable sensor for a selfie stick which is a popular smartphone accessory, fabricated from a piezoelectric PLLA Kumihimo-gumi.

Influence of additives on physico-chemical properties of electrospun poly(L-lactide)

Electrospun poly(L-lactide) (PLLA) nonwoven represent potential options for biodegradable medical implants. They can be manufactured with high reproducibility and do offer the potential for chemical modification to alter matrix properties. In our study, we investigate the mechanical, thermal and morphological properties of PLLA fiber matrices. Fibrous nonwovens were fabricated from polymer solution by needle electrospinning. The polymer solutions were loaded with Triton X-100 (TX- 100), formic acid and tetraethyl ammonium chloride (TEAC) with respect to polymer weight. Morphology of the PLLA nonwoven scaffolds was examined with SEM. We performed uniaxial tensile tests and differential scanning calorimetry (DSC). Different concentrations of the additives TEAC, formic acid and Triton X-100 lead to strong changes regarding mechanical and thermal properties of the electrospun PLLA fiber matrices. In comparison with mechanical properties of established biological tissue materials, the results indicate the suitability for medical applications.

Human skin interactive self-powered wearable piezoelectric bio-e-skin by electrospun poly-l-lactic acid nanofibers for non-invasive physiological signal monitoring

An electrospun PLLA fiber based flexible, piezoelectric bio-e-skin that can detect human physiological signals is presented.

Preparation and Characterization of Spidroin and PLLA Blended Nanofiber Mats

Due to the exceptional biocompatibility of spider silk and poly-L-lactic acid (PLLA), electrospun PLLA or spidroin fiber mat is one of the best biomaterials. The diameter of electropun PLLA fiber decreased and mechanical property of such fiber mats was improved once some spidroin was added into PLLA/Hexaflorisopropanol (HFIP) solution. The influence of electrospinning voltage and distance on the shape and mechanical properties of spidroin/PLLA composite fibers was investigated as well as the molecular conformation and crystalline structure of the electrospun fibers. The results revealed that the diameter of spidroin/PLLA fiber was non-uniform, which varied from 300nm to 1000nm. The content of random coil or α-helix structure was about 45%, and spidroin presented a crystal structure separated with PLLA in their composite fibers. With the raise of voltage, the proportion of nano-sized fibers in an electrospun spidroin/PLLA fiber mat increased and tended to be unchanged. The breaking strength of the mat was improved following the increase of voltage. Meanwhile, the ratio of nano-sized fibers and initial modulus of the spidroin/PLLA fiber mat underwent the convex change against the electrospinning distance between the needle and collector.