An overview of current biosensor
technology
-Introduction to biosensor
Biosensor sounds quite familiar even
to those who do not have special technical background because it is
just natural for people to want to know what is going on with inside
the body, especially when there is any noticeable abnormality or some
symptom.
When technology was not developed
enough, it was future technology. However since first commercialized
glucose biosensor has come out, so much improvements have been taken
place.
So I will write about overview to
glimpse at what has been going on for developing biosensor, and where
the current technology stands now. Since this article is aiming for
covering broadly, I might not be able to cover all different types of
biosensors and characteristics in depth which I plan to do for next
two months(April, May). However, I will try to cover as much as
possible in general.
Biosensors are sensors that
transduce bio-recognition processes into measurable signals via a
physico-chemical transducer, with electronic and optical techniques
as two major transducer(Fan et al 2005)
Simply put, it is a sensor to
detect/monitor biological analytes for various purposes. Roughly it
is divided into three sections. First, the materials that are
actually analyzed and monitored by the sensor such as tissue,
microorganisms, organelles, cell receptors, enzymes, antibodies,
nucleic acids. Then biosensor, obviously, needs physical hardware and
software(system and application).
Also biosensor can be classified by
transducing mechanism – resonant biosensors, optical-detection
biosensors, thermal-detection biosensors, ion-sensitive FET
biosensors, electrochemical biosensors.
1. Hardware
According to Moore’s law, more
transistors are on a single chip, and it increases performances. Now
nanotechnology is rapidly on the way to develop a smaller chip and
higher functions, and biosensor chip field seems hugely favored of
the nano technology.
For the materials of hardware could be
divided into 4 categories – sillicon, compound semiconductors,
organic semiconductors and nano materials.
Not only what kind of materials are
used is concerned, but also how to generate power more efficiently is
another big factor to consider when design a biosensor.
So far, there are photovoltaic,
thermovoltaic, micro fuel cells, electrostatic, electromagnetic and
piezoelectric.
Unlikely in the past when only
individual biosensor is available, it is now shifting to a network.
Like above there are quite many different types of biosensors, and it
seems quite obvious to integrate those sensors into one chip for more
efficiency.
It is now called body sensor network
which implies two types of networks – small(on body) and big
one(information network between user, physician, and server). In
order to make this network, mote which is a sensor node takes place
to connect all information from each different sensors. One of the
most commonly used mote is telos.
2. Software
As far as I understand, the most important role of the software for biosensor is how to make more efficient and robust one. The reason is when we think about how much volume of data are generated by each sensors, it can make a huge delay or error when processing data. Especially, it needs to be real-time monitoring system, the data keeps coming in and needs to be analyzed in a certain speed.
Though there are numerous different software needed for not only system but also application, the outline that I had in my mind was quite simple – operating system for user, physician and sever managers, devices software for requiring all different data from sensors, processing the data program for physician and server and monitoring system.
As I’ve been studying more about it, I’ve discovered more about operating systems, framework, other application softwares.
For operating system, it seems TinyOS is the most commonly used one and there are Mantis OS, Contiki, MANTIS and so on. SPINE(Signal Processing In Node Environment) is developed as an open source framework at UC Berkely, and it is a part of Dexternet which is an open platform for heterogeneous body sensor network and applications.
3. Review and conclusion
Since it is my first attempt to
summarize what I’ve learned this month, I don’t expect it to be
perfect. Yet, I was able to understand about not only about basic structure of
biosensor but also a direction of where biosensor technologies are going to.
From what I learned, besides all major challanges in detail, the main point to make biosensor more accessible is firstly miniaturization of the chip and secondly efficient system infrastructure to support a vast flow of information.
In the next two months, I'm planning to study more about each biosensors that are used to comprise heterogeneous biosensor. The reason is that I believe in order to build such a robust system for body sensor network, it will be quite beneficial to learn about each biosensors characteristics.
Developing software of biosensor has a unique characteristics in which the input is not comprehensible to anybody, and I think it is critical to understand what kind of input the system is dealing with.
Therefore I'd like to maximize my biology background while I'm studying each sensors, and use those knowledges back to when I build such a biosensor system.
4. Reference
- Saraju P. Mohanty, Biosensors: A Survey Report, Nov 24 2001
- David P. Klemer, MD, PhD, Microelectronic Biosensors: Materials and Devices
- Joseph Polastre, The Mote Revolution: Low Power Wireless Sensor Network Devices
- Jonathan Lueke and Wailed A. Moussa, MEMS-Based Power Generation Techniques for Implantable Biosensing Applications
- Shiping Song, Hui Xu, Chunhai Fan, Potential diagnostic applications of biosensors: current and future directions
