UC San Diego
Bridging the Gap Between Technological Advancement and Manufacturability: Development of Solderable Stretchable Sensing Systems
- Author(s): Kim, Yun Soung
- Advisor(s): Coleman, Todd P.
- et al.
In the past decade, development of stretchable, thin-lm electronics have
garnered attention from healthcare industries to general public, since such platform
would enable a direct integration with skin, providing the means of intimate
and unobtrusive health monitoring. However, such transition of the technology to
consumers has been hampered by challenges associated with high-cost, inability
to scale, and low device reliability. To address this, we see an increase in researcheort in adopting the use of rigid, yet small, commercial-off-the-shelf chip components.
The value gained by employing the full sophistication of modern integrated
circuits (ICs) is disproportionate to the slight loss in overall stretchability.
This dissertation aims to provide a unique methodology that weds the bene
ts of both thin-lm and surface mount technologies. However, the focus is
not only on developing the new sophisticated systems but also on scalability of
the manufacturing process. First, we introduce a method to produce a stretchable,
thin-lm interconnection platform exhibiting an excellent solderability with
industry-standard SAC (Sn96.5/Ag3.0/Cu0.5) solder alloy. This platform, which
we call Solderable and Stretchable Sensing System (S4), was further veried for
its feasibility to be scalably manufactured through the demonstrative production
of S4 respiration sensing devices. Finally, we demonstrated the direct integration
of fully assembled S4 devices with a large area adhesive lm, proving the methods
compatibility with a roll-to-roll process.
Next we explored S4s capacity as a platform for wireless communication devices
involving high frequency radio signals, such as those involved with Bluetooth
protocols. We introduced the engineering challenges found in designing thin-lm
conductive traces for reliably accommodating radio frequency RX/TX. As a solution
to these challenges, S4s utilized novel stretchable antennas boasting similar
thin-lm conductive properties, obviating chip antennas and further demonstrating
their versatility as an electronic platform. Finally, we employed S4 devices capable
of physiological monitoring, signal amplication, analog-to-digital conversion, andwireless communication via Bluetooth Low Energy protocols using the integrated
We demonstrated S4s capacity for adopting various surface mount chip
packages, scalable manufacturing and packaging, support for high frequency digital
signals, and transmitting/receiving wireless radio signals. We believe the compatibility
of the manufacturing methods with existing tools and materials, as well
as S4s versatile and modular characteristics successfully tie together the values of
stretchable electronics and advanced IC technologies.