Damalerio, R. B., Lim, R. Q., Wee, J. Y. V., Lim, R. Y., & Cheng, M.-Y. (2023, May). Evaluation of Screen Printing Process in Fabrication of Small Profile Conductive Ink-based Contact Force Sensor. 2023 IEEE 73rd Electronic Components and Technology Conference (ECTC). https://doi.org/10.1109/ectc51909.2023.00083
Abstract:
Incorporating contact force sensor in renal
denervation device provides immediate sensing feedback in
determining ablation quality and improves mechanical catheter
control. Commonly available contact force sensor in catheter
devices is either fiber optic or magnetic in nature. They are
typically located at the distal tip of the catheter. In this work, we
proposed to fabricate small profile contact force sensor using
carbon conductive ink by screen-printing process. This process
maximizes the sensing area of contact. Subsequently, three of
these contact force sensors will be placed 120 degrees apart
around the catheter wall. The force sensor consists of twostacked
polyimide flexible printed circuit boards (FPCB) that
have the same dimension. One has gold over copper interdigital
traces and solder pads while the other has screen-printed carbon
conductive ink, i.e., the sensing element. The printed size of each
force sensor is limited to 2.4mm x 0.60mm x 0.06mm. The
critical dimension is the width which is only a maximum of
0.6mm. The force sensor is piezoresistive in nature. It will be
integrated directly under the micro-electromechanical systems
(MEMS) sensor chip that has the heater electrode to ablate the
renal artery. To fulfill the required alignment holes of the
screen-printing machine, the substrate is designed in a wide
array format with an external dimension of 205mm x 100mm.
Each substrate contains 3 arrays of 15 columns x 3 rows of a
single sensor FPCB. The testing of the force sensor is conducted
on a flat surface with a load range of 50mN to 500mN, which
serves as the baseline to represent the degree sensor contact to
artery wall. Repeatability tests showed that from 50mN -
150mN, the sensitivity of the force sensor is 2.1 KΩ/mN, with a
dynamic response of 70.1%, while 50mN – 500mN is 0.70
KΩ/mN with a dynamic response of 91.4%. The sensor can
differentiate various degrees of contact, which are defined from
light contact (50mN), good contact (150mN), and over contact
(500mN). The overall sensor structure, i.e., integrated MEMS
chip, contact force sensor, and radiopaque material, passed
biological evaluation for medical devices per ISO-10993-5.
License type:
Publisher Copyright
Funding Info:
This research / project is supported by the A*STAR - GAP
Grant Reference no. : EPTCL/19-GAP034-R20H (ACCL190281)