Mechanically Milled Irregular Zinc Nanoparticles for Printable Bioresorbable Electronics

Abstract

Bioresorbable electronics is predominantly realized by complex and time-consuming anhydrous fabrication processes. New technology explores printable methods using inks containing micro- or nano-bioresorbable particles (e.g., Zn and Mg). However, these particles have seldom been obtained in the context of bioresorbable electronics using cheap, reliable, and effective approaches with limited study on properties essential to printable electronics. Here, irregular nanocrystalline Zn with controllable sizes and optimized electrical performance is obtained through ball milling approach using polyvinylpyrrolidone (PVP) as a process control agent to stabilize Zn particles and prevent cold welding. Time and PVP dependence of the ball milled particles are studied with systematic characterizations of morphology and composition of the nanoparticles. The results reveal crystallized Zn nanoparticles with a size of ≈34.834 ± 1.76 nm and low surface oxidation. The resulting Zn nanoparticles can be readily printed onto bioresorbable substrates and sintered at room temperature using a photonic sintering approach, leading to a high conductivity of 44 643 S m for printable zinc nanoparticles. The techniques to obtain Zn nanoparticles through ball milling and processing them through photonic sintering may potentially lead to a mass fabrication method for bioresorbable electronics and promote its applications in healthcare, environmental protection, and consumer electronics.

Room Temperature Electrochemical Sintering of Zn Microparticles and Its Use in Printable Conducting Inks for Bioresorbable Electronics

“…Sintering, an atomic scale diffusion process that can lead to dense, solid materials from powder precursors without bulk melting, represents a commonly used means for joining metal particles to yield conductive traces from printable inks . Typically, sintering follows from energy introduced into the system by thermal, optical, or electrical means . In certain cases, solid phase sintering can occur spontaneously upon physical contact of two clean surfaces, as with noble metals at low temperatures, sometimes known as cold welding .…”

“…Electroless deposition, as another alternative for low‐temperature fabrication of metal films, has not been reported with bioresorbable metals, possibly due to their strong reducing power, despite its successful demonstration with Cu or Ni . As a result, although recent work describes some interesting chemistries suitable for use of some of these metals in inert environments or at elevated temperatures, they have limited applications for the construction of bio/ecoresorbable electronic devices, especially that require thick metal traces over large areas …”

Fully transient electrochemical testing strips for eco-friendly point of care testing

“…Na-CMC substrate is cheaply available and can be quick degradable. 15,25,31 PVA is an ideal substrate candidate for its multi-advantages including being non-toxic, noncarcinogenic, and soluble in many solvents. Generally, the solubility of PVA in the solution relies on the degree of polymerization and solution temperature.…”

“…5 Polymers (e.g., silk broin, 10 poly(lactic-co-glycolic acid) (PLGA), 11 poly(vinyl alcohol) (PVA), 12 poly(caprolactone) (PCL), 13 polyvinylpyrrolidone (PVP), 14 etc. ), water-soluble sodium carboxymethyl cellulose (Na-CMC) 15 and natural materials [16][17][18] (e.g., egg albumen, natural pectin, natural wax) have been reported to serve as substrates or encapsulation layers of transient electronics. Even some dielectric materials such as SiO 2 and Si 3 N 4 can be used for encapsulation.…”

Low‐Cost Manufacturing of Bioresorbable Conductors by Evaporation–Condensation‐Mediated Laser Printing and Sintering of Zn Nanoparticles

“…Laser (or light) reduction of nanoparticles, facilitated by thermal instability of oxides, has also been demonstrated for Cu x O and NiO . Laser/flash sintering of biodegradable metal nanoparticles (such as Zn) has been attempted, with the highest conductivity achieved is ≈4 × 10 4 S m −1 . The readily formation of surface oxide layers prevents further increase of conductivity.…”