Printed sensors: enabling new applications
NANOIDENT Technologies AG, Linz, Austria
Purpose – This paper aims to discuss the new applications enabled by printed sensors.
Design/methodology/approach – The paper discusses how silicon-based sensors are manufactured using the time-consuming, expensive, and
complicated fabrication process of traditional semiconductor devices and shows what is needed in order to produce such new devices with the
advantages of printed sensors.
Findings – With new materials, new processing technologies and a new manufacturing process, thin, ﬂexible, lightweight, cost-effective sensors are
made possible through the power of printed semiconductors.
Originality/value – This paper should be of value in terms of understanding the pros of printed semiconductors and the resulting sensors which have a
number of unique mechanical, electrical, and optical properties.
Keywords Printed circuits, Sensors, Silicon, Semiconductor devices
Paper type Research paper
The opportunity: new applications
Across industries, in markets as diverse as medicine, national
security, consumer electronics, banking, and food, a change is
brewing. In virtually every industry, new sensors promise to
make the world healthier, more secure, and more
entertaining. However, a few key technological and ﬁnancial
obstacles have until recently hindered their development.
Although these applications seem unrelated, they share
Mobile lab-on-a-chip. Medical and environmental samples,
such as blood or water, can be collected and instantly
analyzed at the point of use, eliminating the need for lab
handling of medical, environmental, and chemical/
biological defense tests. Real-time test results enable a
quick, possibly life-saving response to disease or
contamination. However, most lab-on-a-chip systems
today still require bulky, expensive reader equipment,
limiting cost-effectiveness and practicality. To be truly
mobile, the sensor must be integrated onto the chip; this
means that it must be small and low-cost, since such chips
are for one-time use only.
Biometric smart cards and mobile devices. A ﬁngerprint
veriﬁcation system is embedded onto cards or mobile
electronics for identiﬁcation, banking, m-commerce and
other applications, providing a reliable means to verify
personal identity without the need for passwords or PINs.
To ensure the highest level of privacy protection, the
ﬁngerprint sensor, along with processing software and the
owner’s biometric reference data, must be located directly
on the secure device; any other architecture puts the user’s
personal data at risk. However, a silicon chip capable of all
of this would be too rigid to withstand being placed in
pockets, sat on, dropped, etc. Such a device must be
extremely ﬂexible and rugged, as well as inexpensive.
Smart food packaging. A sensor is integrated into food
packaging to provide real-time indication of freshness.
The sensor could directly detect the signs of meat, ﬁsh or
dairy product spoilage, offering a much more reliable
result than use-by dates, surface color and smell. For such
a high-volume application, the sensor and indicator must
be extremely inexpensive, as well as ﬂexible. Silicon is
simply too expensive for such an application.
The problem: silicon
Today’s silicon-based sensors are manufactured using the
time-consuming, expensive, and complicated fabrication
process of traditional semiconductor devices (Figure 1).
This process can involve hundreds of steps, in which
conducting, semiconducting, and insulating materials are
deposited, masked, etched, and extraneous material removed.
To achieve the correct electrical properties impurities are
introduced through other complex processes such as ion
implantation. To produce a single batch can take several
weeks, in a fab costing billions of dollars staffed by thousands
of highly skilled specialists.
Since, they are based on silicon, these sensors are rigid and
brittle, and are limited to a relatively thick proﬁle and small
area. Creative attempts to work around these limitations –
such as shaving off some of the substrate for a thinner, more
ﬂexible device – add further cost and complexity, and still
are not sufﬁcient to create robust, bendable, rollable, and
foldable devices. These new requirements call for a new
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28/1 (2008) 6– 11
q Emerald Group Publishing Limited [ISSN 0260-2288]