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

Abstract

Biodegradable or eco-degradable electronics is an emerging field of technology capable of reducing the excessively increasing electronic waste originating from the rapid development of personalized and bio-integrated devices and skin adhesive patches. Through an advantageous solution process, biodegradable conductive pastes can be employed in various applications of soft and flexible devices. Herein a biodegradable conductive paste composed of molybdenum (Mo) microparticles and polybutylene adipate terephthalate (PBAT) exhibiting excellent mechanical flexibility and stretchability is reported, while also demonstrating substantially superior mechanical and conductive properties compared with previously reported biodegradable polymer matrices such as poly butanedithiol 1,3,5-triallyl-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione pentenoic anhydride (PBTPA) and Candelilla wax (CW) owing to the significant elongation of PBAT. Moderate dissolution in phosphate buffer saline (PBS) accomplishes its full biodegradability and programmable lifecycle. Tetraglycol (TG) enhances elongation and conductivity performance by acting as a lubricant and improving the dispersion of microparticles. The practical implications of the Mo/PBAT pastes are demonstrated in numerous biodegradable electronic applications such as electrodes, strain and temperature sensors, joule heaters, interconnectors, and freestanding radiofrequency (RF) coils.

Accelerable Self-Sintering of Solvent-Free Molybdenum/Wax Biodegradable Composites for Multimodally Transient Electronics

“…Based on the experimental data in Figure 1f (black circles) and eq 1, the critical volume fraction and critical exponent are calculated as 0.17 (weight fraction: ∼2.1) and 1.9, respectively, which are comparable to the previous work. 24 Notably, the fitting result (red solid line) also agrees well with the theoretical plot (red dotted line), with a slight deviation that can be attributed to the uneven distribution of Mo particles inside the composite. Although composites with a high Mo/wax volume fraction (such as 0.37) can lead to a high conductivity, they are too dense and sticky to be stirred and printed.…”

Recent Progress on Bioresorbable Passive Electronic Devices and Systems

“…Another important material for bioresorbable passive devices is the conductor, which can serve as electrodes for both resistors and capacitors, coils for inductors, and electrical interconnections for their integrations. Appropriate metallic materials for bioresorbable conductors include magnesium (Mg) [ 46 , 47 ], zinc (Zn) [ 14 , 48 , 49 , 50 ], tungsten (W) [ 29 , 40 , 51 , 52 ], iron (Fe) [ 29 , 53 ], molybdenum (Mo) [ 4 , 12 , 15 ], and their alloys [ 43 , 54 ]. In addition, bioresorbable composite conductors consisting of metallic nano/micro-materials (such as particles and wires) and polymer matrix are also of increasing interest.…”

“…Resistors are commonly used to control the current flow in electronic circuits. Changes in resistivity, length, or cross-sectional area of the material that utilized to construct resistors will induce changes in the resistance, thereby forming the fundamentals of most resistor-type sensors, for example temperature sensors [ 11 ] and pressure/stress sensors [ 12 , 13 , 14 , 15 , 16 ]. Capacitors are mainly used for signal filtering or temporary charges storing in electronic circuit.…”

“…12, 600 10 of 23 which was a mixture of W and poly (ethylene oxide), as the interconnection bridge for multilayer transient printed circuit boards[97]. As schematically shown in Figure5a, multilayers of commercial-of-the-shelf components were electrically connected and fixed on Mg contact pads by the developed transient conductive paste.…”

A Composite Microfiber for Biodegradable Stretchable Electronics

“…Recently, stretchable electronic materials that can be integrated seamlessly with deformable, dynamic, and irregular surfaces, particularly on the human body, have presented new opportunities for wearable applications [ 1 , 2 , 3 , 4 , 5 , 6 ]. In addition to stretchable electronics, transient electronics built with biodegradable materials are of increasing interest for future wearable and implantable applications [ 2 , 6 , 7 , 8 , 9 , 10 ]. Furthermore, a range of biodegradable devices could attain a high level of functionality by introducing stretchability and the thoughtful merging of soft-to-hard materials [ 11 ].…”