Maskless Patterning of Biodegradable Conductors by Selective Laser Sintering of Microparticle Inks and Its Application in Flexible Transient Electronics

Abstract

Biodegradable electronic devices are able to break down into benign residues after their service life, which may effectively alleviate the environmental impacts as a consequence of the proliferation of consumer electronic technology. The widespread adaptation to biodegradable systems is currently impeded by the lack of economic fabrication techniques for functional devices. Here, a facile approach to generate a biodegradable conductor is developed based on selective laser sintering of zinc and iron microparticle ink. The sintering process is effective to convert naturally oxidized microparticles into interconnected conductors. Arbitrary conductive features are readily created over flexible biodegradable substrates under ambient conditions, which exhibits excellent conductivity (∼2 × 106 S m–1), low sheet resistance (∼0.64 Ω □ – 1), fine feature resolution (∼45 μm), and mechanical flexibility. The practical suitability is demonstrated by fabricating a miniaturized near-field communication tag with the dimension to mount on the fingernail. The methodology is further extended to create a metallic grid as a biodegradable transparent electrode with low sheet resistance (2.5 Ω □–1) and high optical transmittance (96%), which is employed as an epidermal transparent heater for thermotherapy. Maskless patterning of biodegradable conductors may find a broad range of applications in environment friendly gadgets and implantable medical devices.

Biodegradable Molybdenum/Polybutylene Adipate Terephthalate Conductive Paste for Flexible and Stretchable Transient Electronics

“…[23][24][25][26][27][28][29][30][31][32] For example, fully functional and biodegradable sensors (including strain and temperature sensors) along with multiple arrays of printed circuit boards and RF inductive devices have been successfully realized through ink-jet and screen-printing methods utilizing biodegradable composite paste containing water-soluble metal microparticles (e.g., Mg, Zn, Mo, W) and biodegradable polymers such as poly(ethylene oxide) (PEO), PBTPA, natural waxes, polycaprolactone (PCL), poly-l-lactic acid (PLA), poly lactic-co-glycolic acid (PLGA), polyvinylpyrrolidone (PVP), and polyvinyl alcohol (PVA). [23][24][25][26][27][28][29][30][31][32] The polymer matrix of biodegradable conductive pastes plays an important role in determining their overall mechanical properties, as well as their dissolution and swelling behavior. [23][24][25][26][27][28][29][30][31][32] Early versions of such pastes based on Zn, W microparticles and PEO were susceptible to rapid dissolution owing to the fast degradation behavior of PEO.…”

“…[ 23–32 ] For example, fully functional and biodegradable sensors (including strain and temperature sensors) along with multiple arrays of printed circuit boards and RF inductive devices have been successfully realized through ink‐jet and screen‐printing methods utilizing biodegradable composite paste containing water‐soluble metal microparticles (e.g., Mg, Zn, Mo, W) and biodegradable polymers such as poly(ethylene oxide) (PEO), PBTPA, natural waxes, polycaprolactone (PCL), poly‐l‐lactic acid (PLA), poly lactic‐ co ‐glycolic acid (PLGA), polyvinylpyrrolidone (PVP), and polyvinyl alcohol (PVA). [ 23–32 ]…”

Eco‐Friendly Electronics—A Comprehensive Review

“…Mahajan et al [304] proposed the manufacturing of zinc nanoparticles by planetary ball milling, which can be directly screen or sprayprinted onto bioresorbable substrates, cured at room temperature, and sintered by photonic methods. Shou et al [303] and Feng et al [307] opted for laser based techniques to transfer conductive zinc features onto biodegradable substrates under ambient conditions. Lee et al [308] proposed electrochemical sintering for aqueous metal inks (based on zinc) especially for large areas application, at room temperature within several minutes.…”

“…[ 303 ] and Feng et al. [ 307 ] opted for laser based techniques to transfer conductive zinc features onto biodegradable substrates under ambient conditions. Lee et al.…”

Laser digital patterning of conductive electrodes using metal oxide nanomaterials

“…More recently, several studies indicated that the LDP of ZnO thin films allows the fabrication of transient electronic devices that can disappear completely or partly upon exposure to water at prescribed rates or within a prescribed time period [54][55][56]. Shou et al reported a low-cost laser process for ZnO NP films to fabricate Zn conductors on a bioresorbable sodium carboxymethyl cellulose (Na-CMC) substrate [55].…”