A device for detecting dielectric properties of electrically small-sized samples based on near-zero transmission method

Abstract

The invention discloses a dielectric property detection device for electrically small-sized samples based on a near-zero transmission method. The dielectric property detection device is an asymmetrical three-port network, specifically including a bottom metal layer, a middle dielectric layer and an upper metal strip; wherein , the upper metal strip includes a microstrip type Wilkinson power divider, a 90-degree 3dB branch line coupler, two branches and electric field enhancement branches loaded on the two branches, two electric field enhancement branches The section constitutes the test and reference area of ​​the dielectric property detection device, and the microfluidic channel is loaded in the test and reference area; when the two microfluidic channels are loaded with the same sample or the device is unloaded, the dielectric property detection device is in a symmetrical balance state, there will be two transmission zero points, when the sample loaded by the two microfluidic channels has a small difference, the transmission zero point of the dielectric property detection device will change. The invention is convenient to use, low in price and easy to integrate.

Description

technical field [0001] The invention relates to a microwave detection device for small changes in dielectric properties of materials. The invention belongs to the technical field of microwave measurement, and more specifically relates to a three-port dielectric characteristic small change measurement device. Background technique [0002] With the rapid development of microwave technology, the research of many problems is promoted by the detection of small changes in the dielectric properties of fluids, such as thermal denaturation of proteins in the biological field, double plasma membranes, single-cell properties, and microwave chemistry. Internal non-thermal effect research, etc. These small changes may be caused by the very small measured fluid, that is, the measured object is a microfluid, or the small changes in the temperature and concentration of the measured fluid, or the slight shift of the microstructure of the measured fluid caused by the external field, resultin...

AI Technical Summary

Problems solved by technology

[0003] The near-zero transmission method provides a new idea for the detection of small changes in the dielectric properties of materials. This method uses the principle of two-branch cancellation to eliminate background noise and achieves good results. The application numbers are 201510982684.4, 201610880142.0 and 201710186355.8. Starting from this point, a detection device based on the coplanar waveguide transmission line was proposed, which achieved certain results. However, these devices are all two ports, and a near-zero transmission circuit with a transmission zero point can only reflect the change of the real part of the dielectric property of the measured object. The information of the measured object that can be obtained is limited, and although the coplanar waveguide transmission line type device has high sensitivity, it needs to add additional leads when encountering a right-angle turn. The diameter of the lead is about 25 microns, which is vulnerable to weak external force. Breakage and falling off occur, so the test process has high requirements on the external environment, and the service life of the test device is also greatly shortened due to the lead wires, or each additional test requires another lead wire to be welded, resulting in an increase in the cost of the test

And the electric field strength of the test area and the reference area of ​​the above-mentioned documents is generally within 10 4 V / m, research shows that the electric field enhancement in the test area can greatly improve the test sensitivity, so the test sensitivity needs to be further explored

Images