Cellular Imaging

• Microscopic Electrical Impedance Imaging

• Scanning Impedance Imaging (SII)

  A typical SII system consists of two primitive components as illustrated in Fig. \ref{fig:SII}: an impedance probe scanned in high resolution, and a conducting solution surrounding the sample and the probe that forms a virtual path between them. A current image can be obtained by taking measurements with a shielded probe scanned above the sample. It can be seen that the shielded probe has a coaxial geometry with a metal tip in an insulator surrounded by a metal shield. The motivation of this new probe design is to eliminate the effects of the current flux from the region not directly under the end of the probe. This innovative probe design results in higher resolution by shrinking the average cross-section area of current flow through the sample between the tip and the conducting plane. Further, the shield can help to eliminate the noise generated by the entire conducting plane. When the probe moves across the material, the current flux through the tip will change according to the impedance under it. So the impedance map of the material can be achieved by using the current measurements of all positions.

  In our SII system, we introduce the non-contact configuration and high-resolution scanning technique to the typical electrical impedance imaging device. The non-contact configuration ensures a consistent electrical contact everywhere and high resolution scanning enables us to take sufficient measurements in small scales, which leads to a high resolution reconstructed image.

• Rotated Bi-Probe Imaging (RBP)

  Besides SII system, we consider another approach with the scanning setup substituted by the rotation, which is described as a rotated bi-probe (RBP) system. Fig. \ref{fig:rbp} shows the principle of a typical RBP system. A pair of probes is placed opposite each other with a sample at the center. A conduction medium surrounds the probes and the sample. A voltage is applied to the pair of probes and the current through is measured. The distinction of this innovative design is the rotation of the probes that can produce rings of measurements at different depths. Although the ring form of measurements is similar to the classical EIT system, RBP demonstrates three major advantages. First, there are only two probes instead of 32 even 128 probes in our system, which dramatically reduces the difficulty of the instrumental construction so that micro-scale measurements can be taken. We know that it is nearly impossible to integrate at least 32 probes in cellular level. Second, the amount of measurements only depends on the rotate speed and the sampling rate. Hence, we can obtain adequate measurements by decelerating the rotate speed, increasing the sampling rate, or both. Furthermore, helix measurements can be obtained by moving the probes in the third direction. Thus, 3D impedance reconstruction can be performed.

• Probe-Array System (PA)

  Both SII and RBP require motion controllers that could be a problem in a micro system, while the probe-array system uses an array of micro probes instead of moving probes as illustrated in Fig. \ref{fig:pa}. A voltage signal is applied to all the probes at the same time and a current measurement is taken for every probe separately. Thus, sufficient measurements can be obtained without any movement. However, a new problem of data collection emerges in this configuration. One applicable way is to observe the thermal effects generated by the currents using an infrared microscope.

• Quasi-Elastic Microwave-induced Laser Scattering

This multi-modality imaging method uses microwave excitation and laser scattering to image cells.

Project Navigation Menu

• General Information
• Documentations
• Software, Hardware
• Results
• Discusion

Quick Back

• <<< Lab Home
• Department Home