Next-generation Consumer, Medical
Products Drive Sensor Advances
MEMS facing competition from printed, flexible sensor technologies
By Spencer Chin, Managing Editor
For many years, sensors that incorporate MEMS (
Micro-Electro-Mechanical Systems) technology were considered
among the state-of-the-art. Although MEMS continues to
benefit from process and production improvements, the
technology faces increasing competition from printed and
flexible technologies, according to industry analyst Roger
Grace of Roger Grace & Associates.
Grace believes printed/flexible sensors will find their
way into a number of wearable and disposable sensor
applications in the health and medical field, due to their small
size, low profile, ability to conform to attaching surfaces, and
low manufacturing cost on existing batch mode processing.
The key, according to Grace, is reducing manufacturing
costs. Grace and other industry followers assert that printed/
flexible sensors will become a more attractive proposition once
high volume, roll-to-roll manufacturing can be scaled up to
lower production costs. Roll-to-roll manufacturing is expected
to lower capital expenditures and eliminate costly clean room
equipment requirements that are needed for MEMS.
One company that has already established roll-to-roll
manufacturing of flexible sensors is Si-Cal Technologies
Inc. (Westborough, MA), a business unit of Japan’s Nissha
Printing. According to Jaye Tyler, president and CEO OF
Si-Cal, the company has been doing roll-to-roll manufacturing
of wearable medical sensors for several years, with volume
capabilities of 10,000 to 100,000 parts per production run.
To date, parts produced by Si-Cal a sensor to detect oxygen
flow, a diabetes sensor, a two-way sensor to stimulate nerves,
and an esophageal sensor tube to alert surgeons.
Recently, Nissha USA Inc. acquired the printed electronics
business of GSI Technologies Inc. Tyler expects the acquisition
to bolster the company’s capabilities in printed electronics, to
meet growth demands for wearable medical sensors.
Challenges to roll-to-roll manufacturing remain, according
to Tyler. Asides from the fact the part production volumes
need to ramp up to realize cost benefits, Tyler notes relatively
few inks have been formulated for high-speed printing, and
that the inks available to date often require high deposit
thicknesses and are relatively slow to dry. “However, ink
suppliers are actively tackling this issues,” he adds.
Grace is bullish on the technology. “The key to success
in the commercialization of printed/flexible sensors are not
the sensors themselves but rather will be in their expected
low cost and their ability to solve application problems which
leverage their inherent benefits and the ability for a solution
to include more than just a sensor in the total deliverable
solution,” says Grace in a recent research report.
The key driver in sensor technologies, Grace adds, is the
end market applications.
“Silicon MEMS sensors were driven by the mobile phone
market,” he says. Grace estimates there are now 1.3 billion
smart phones alone in the world, all of which use MEMS
sensors. “(But) now the market is leveling off; there’s not
that much more opportunity in smart phones.”
Market research firm ID TechEx has projected that the
market for fully printable sensors will be more than $6 billion
of the $340 billion flexible global electronics market by 2030.
As with Grace, the firm expects significant applications to be
sensors used in sports/health activity/fitness applications.
So far, flexible sensors are in relatively limited production.
TEKSCAN has developed a force sensor fabricated between
two polyester film substrate layers. A high-temperature
version of the sensor (Figure 1) is constructed with two
polyamide layers, a conductive silver layer followed by a
layer of pressure-sensitive ink. Adhesive is used to laminate
both substrate layers together to form the force sensor. The
active sensing area is defined by the silver circle atop the
pressure-sensitive ink. Silver traces from the sensor area
to the connectors on the other end of the sensor forms the
The barriers to roll-to-roll manufacturing, according to
Tyler, stem partially from the fact that relatively few inks have
been formulated for high-speed printing, and that the inks
available to date often require high deposit thicknesses and
The growth of the Internet of Things (IoT), wearable electronics, advanced medical
products, and other applications has triggered
a demand for sensors with advanced sensing
capabilities that can fit into tight spaces, have
extremely high resolution and accuracy, and
consume low power. At the same time, the need
for higher integration and value-added electronics
assemblies is increasing the need for sensors
able to perform multiple sensing functions. These
requirements have prompted sensor maker to inject
new and improved technologies in their parts.
Figure 1. A high-temperature version of TEKSCAN’s flexible sensor is
constructed with two polyamide layers, a conductive silver layer followed
by a layer of pressure-sensitive ink.