Development of Electroplated Magnesium Microstructures for Biodegradable Devices and Energy Sources

Abstract

This paper presents fabrication approaches for magnesium (Mg) microstructures embedded in biodegradable polymers using through-mold Mg electrodeposition and metaltransfer-molding. Biodegradable implantable electronics have garnered increasing interest from the medical community for the monitoring and treatment of transient diseases. Magnesium is a biodegradable metal with desirable properties, and the ability to micropattern Mg thick films (i.e., about >1 µm) with direct microelectromechanical systems (MEMS) integration would support the development of more sophisticated and clinically relevant biodegradable devices and microsystems. Magnesium microstructures were electroplated through micropatterned water-soluble molds in a nonaqueous electrolyte and transfer molded into a biodegradable polymer. Electroplated Mg compared favorably with commercial Mg foil based on elemental composition, crystal orientation, electrical resistivity, and corrosion behavior. Magnesium electroplated to a thickness of up to 50 µm showed a grain size of ∼10 µm, and minimum feature dimensions of 100 µm in width and spacing. Completely biodegradable Mg and poly-L-lactic acid constructs were demonstrated. The application of Mg thick films toward biodegradable energy sources was explored through the fabrication and testing of biodegradable Mg/Fe batteries. The batteries exhibited a capacity and power of up to 2.85 mAh and 39 µW, respectively. Results confirmed the advantages of electrodeposited Mg microstructures for biodegradable MEMS applications. [2014-0103]

Materials and Orthopedic Applications for Bioresorbable Inductively Coupled Resonance Sensors

“…On the other hand, several tens of micrometers thick Mg and Zn microstructures have been obtained by electroplating the conductor patterns onto a temporary substrate and subsequently transfer printing them onto bioresorbable substrates. 15 , 54 Further approaches include conductive ink printing methods that do not require vacuum technology and would thus be beneficial for scaling the manufacturing processes. 14 , 55 These methods are currently under development, but the nonconductive surface oxide layers on biodegradable metal particles make their development challenging.…”

Powering Implantable and Ingestible Electronics

“…Recently, most of the studies on implantable galvanic cells have been focused on fabrication techniques to make the galvanic cells thin and flexible or on creating biodegradable electrode or electrolyte materials. [194,197,[379][380][381] However, galvanic cells that harness energy from interstitial fluid produce less power compared to those that harness energy from gastric fluid. This can be potentially explained by the higher pH, or lower concentration of hydrogen ions, of the interstitial fluid.…”

Materials, Processes, and Facile Manufacturing for Bioresorbable Electronics: A Review

“…Synthetic biodegradable polymers, such as poly(lactic acid) (PLA), [46,127,128] poly(glycolic acid) (PGA), poly(lactic-co-glycolic acid) (PLGA) [29,44,45,91,101] , polycaprolactone (PCL) [21] and poly(3hydroxybutyrate-co-3-hydroxyvalerate) (PHB/V) [48,54] are some of the key materials for biomedical applications including tissue engineering devices, drug delivery systems and body implants. [80,81,129] They are well-suited for bioresorbable electronics with known innocuous byproducts formed during in vivo degradation.…”