[Journal for independent biosensor research] Overview of current biosensor technology

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