Micro Printing Using Microfluidics for Printed Biodegradable Devices in Trillion Sensing
Authors: Terasaki Nao , Dorsey Kristen , Makihata Mitsutoshi , Pisano Albert P 
Published: February 2020

Printed and biodegradable devices are a promising technology for the up-coming trillion sensor universe, in which over a trillion networked sensors annually will be used for smart solution for global social problems, such as energy, food, manufacturing, and infrastructure [1]. To achieve this universe, a hundred-fold increase in networked sensors must use the same order of resources as current sensors, with at most 1% of cost and environment impact of traditionally fabricated sensors. From this viewpoint, we investigated a fabrication process for printed biodegradable devices and here successfully prepared micro-printed pattern of metal nanoparticles on biodegradable polymer substrate for the first time. Such processes would enable flexible, disposable, and environmentally friendly electronics for the trillion sensors universe.
This printed fabrication process uses a template to guide metal nanoparticle ink deposition. A polymer (e.g., poly dimethyl siloxane, poly 4-methyl 2-pentyne) template with nano- or micro- patterned channels was put on the biodegradable polymer substrate. Then, the nanoparticle ink was injected into the channel to form the desired pattern. Further details of this process are described in [2, 3]. To prepare the biodegradable polymer film, a biodegradable polymer (poly lactic acid (PLA), poly caprolactone (PCL), or poly (3-hydroxybutyrate- co- 3-hydroxyvalerate) (PHBV)) in pellet form was dissolved in dichloromethane with various concentrations and cast on a petri dish to prepare various thickness of substrate from 10 through 200 mm.
As the result, a micro- printing pattern on PLA film is shown. The thickness of the PLA film was measured as ca. 150 μm. The material and printed metal pattern retain their flexibility. From optical microscopic measurements, we confirm that the interdigitated comb pattern was transferred to the PLA substrate. This shape was consistent with the original micro pattern on the surface of the template. Further, the SEM image demonstrates the interdigitated comb pattern is comprised of closely-packed Ag nanoparticles. In the presentation, we will discuss the micro printing of metal nanoparticles for printed biodegradable devices from the viewpoint of effect of kinds of biodegradable materials, surface roughness and morphology, and the effect of contact angle on printing success and fidelity. We will consider the adaptability of biodegradable polymer for printed electronics and devices.
Acknowledgement
This research was partially financially supported by the Walter J. Zable Chair in Engineering at UC San Diego and AIST short-term fellowship, and Grant-in-Aid for Scientific Research (B). NT shows gratitude to all members of PRIME in UC San Diego and UC Berkley, for example Mr. Shunichi Arakawa (UCSD), Mr. David Rolfe and Mr. John Herr (UC Berkley). Some measurement such as SEM was supported by NANO3 staff member in UC San Diego.
Reference
[1] J. Bryzek, Roadmap for the Trillion Sensor Universe
[2] M. T. Demko, J. C. Cheng, A. P. Pisano, ACS Nano, 6, 6890 (2012).
[3] M. T. Demko, T. M. Blackbill, A. P. Pisano, Langmuir, 28, 9857 (2012).
[4] As review, L. S. Naira, C. T. Laurencin, Prog. Polym., Sci. 32, 762 (2007).