A Novel Strategy to Fabricate Core-Sheath Structure Piezoelectric Yarns for Wearable Energy Harvesters

Wearable and portable electronic devices based on textile structure have been widely used owing to their wearability and comfortableness.However,yarn fineness and the comfort of the fabric cannot satisfy the requirements of smart wearable devices.This work presents a novel strategy to prepare highly integrated PVDF/conductive nylon core-sheath structure piezoelectric yarns for wearable which is fabricated by combining electrospinning strategy with 2D braiding technology.The fineness of single yarns as well as strength are both improved significantly compared to previous works.The piezoelectric outputs of the yarn are still stable after 800 s fatigue test at a frequency of 4 Hz,and the cycle stability can maintain more than 3200 cycles.Furthermore,the piezoelectric yarns are further woven into piezoelectric plain fabric.According to the electrical performance,the length of the piezoelectric yarn and the thickness of the piezoelectric layer would both affect the output electrical performance.The yarn of the 10 cm in length and 600μm in fineness can produce an output voltage of 120 mV.Meanwhile,Both the piezoelectric yarn and the fabric could generate piezoelectric output signals through human movement,such as bending,walking.Therefore,the electrical and mechanical performance of the piezoelectric yarns prepared in our work could be improved significantly,and the comfortableness and durability performance of the piezoelectric fabric can satisfy most wearing requirements,which would provide some help in the field of piezoelectric wearable devices based on yarns and fabrics.

Development of a polycaprolactone/poly(p-dioxanone)bioresorbable stent with mechanically self-reinforced structure for congenital heart disease treatment

Recent progress in bioresorbable stents(BRSs)has provided a promising alternative for treating coronary artery disease.However,there is still lack of BRSs with satisfied compression and degradation performance for pediatric patients with congenital heart disease,leading to suboptimal therapy effects.Here,we developed a mechanically self-reinforced composite bioresorbable stent(cBRS)for congenital heart disease application.The cBRS consisted of poly(p-dioxanone)monofilaments and polycaprolactone/poly(p-dioxanone)core-shell composite yarns.Interlacing points in cBRS structure were partially bonded,offering the cBRS with significantly higher compression force compared to typical braids and remained good compliance.The suitable degradation profile of the cBRS can possibly preserve vascular remodeling and healing process.In addition,the controllable structural organization provides a method to customize the performance of the cBRS by altering the proportion of different components in the braids.The in vivo results suggested the cBRS supported the vessel wall similar to that of metallic stent.In both abdominal aorta and iliac artery of porcine,cBRS was entirely endothelialized within 1 month and maintained target vessels with good patency in the 12-month follow-up.The in vivo degradation profile of the cBRS is consistent with static degradation results in vitro.It is also demonstrated that there is minimal impact of pulsatile pressure of blood flow and variation of radial force on the degradation rate of the cBRS.Moreover,the lumen of cBRS implanted vessels were enlarged after 6 months,and significantly larger than the vessels implanted with metallic stent in 12 months.