Path: EDN Asia >> Design Ideas >> Medical >> Inductive sensing for biomedical applications
Medical Share print

Inductive sensing for biomedical applications

01 Jul 2014  | Chii-Wann Lin

Share this page with your friends

Editor's note: This entry is one of the runners-up in the TI LDC1000 inductive sensor design contest.

A left-handed (LH) antenna based biosensor is developed to investigate the near-field electromagnetic interaction between antenna and sample with different dielectric properties. These dielectric properties can be determined by analysing the electromagnetic coupling between the antenna and the test samples without labelling or chemical reaction. It has the advantages of real-time detection, small feature size, reduced sample volume, and minor environmental disturbance. Such an antenna sensor can be effectively used to measure both liquid and solid biological samples.

We propose to use this new inductive to digital sensor (LDC1000) to further enhance the performance by using the measured signal for precise distance and volume control in the sample chamber, and to integrate the antenna-LDC1000 unit into a handheld device. We will be able to demonstrate its potential uses in water contents of biological tissues, biomarkers of in-vitro diagnostics, and content differences in food industry.

The antenna biosensor's LH capacitance (CL) is attributed to the interdigital capacitors coupling between the patch, and LH inductance (LL) is due to the shorted-stub inductances to ground. The LH effects are due to the capacitive (CR) coupling between the patch and ground plane, and the current flow atop the patch. The proposed antenna-based biosensor is made on FR4 PCB substrate. All simulations in this work were carried out using Ansoft HFSS 12.0. The measurement instrument was an RF network analyser, Agilent E5071B. The different concentrations of ethanol solution ranged from 3% to 100%, and the values of equivalent permittivity are 79 to 14. Currently, the measurement done by using a network analyser has hindered its practical clinical and home sensing applications.

Our preliminary results from the LDC1000 indicate the feasibility of such a coupling sensing mechanism. As shown in the uploaded video, the readings from water samples on the coil antenna do have significant changes compared to a control experiment. However, our fabricated left-handed antenna exhibits a characteristic resonance frequency near 1GHz, which is significantly higher than the LDC nominal specifications. We are currently trying to redesign a new antenna for further exploration.

Watch the video on this design here.

About the author
Chii-Wann Lin contributed this article.

To download the PDF version of this article, click here.

Want to more of this to be delivered to you for FREE?

Subscribe to EDN Asia alerts and receive the latest design ideas and product news in your inbox.

Got to make sure you're not a robot. Please enter the code displayed on the right.

Time to activate your subscription - it's easy!

We have sent an activate request to your registerd e-email. Simply click on the link to activate your subscription.

We're doing this to protect your privacy and ensure you successfully receive your e-mail alerts.

Add New Comment
Visitor (To avoid code verification, simply login or register with us. It is fast and free!)
*Verify code:
Tech Impact

Regional Roundup
Control this smart glass with the blink of an eye
K-Glass 2 detects users' eye movements to point the cursor to recognise computer icons or objects in the Internet, and uses winks for commands. The researchers call this interface the "i-Mouse."

GlobalFoundries extends grants to Singapore students
ARM, Tencent Games team up to improve mobile gaming

News | Products | Design Features | Regional Roundup | Tech Impact