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Multichannel cell detection in microcompartments by means of true parallel measurements using the Solartron S-1260

T.A. Nguyen
T.A. Nguyen
, 
D. Echtermeyer
D. Echtermeyer
, 
A. Barthel
A. Barthel
, 
G. Urban
G. Urban
 y 
U. Pliquett
U. Pliquett
   | 24 jul 2020
Journal of Electrical Bioimpedance's Cover Image
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Publicado en línea: 24 jul 2020
Páginas: 49 - 56
Recibido: 20 abr 2020
DOI: https://doi.org/10.2478/joeb-2020-0008
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© 2020 T.A. Nguyen et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig.1

The image of a packaged electrode chip with double side PCB suitable for the multiplexer and the insert image which enlarged microelectrode array.
The image of a packaged electrode chip with double side PCB suitable for the multiplexer and the insert image which enlarged microelectrode array.

Fig.2

Principle schematic of the true difference frontend (left panel) for Solartron S-1260 (right panel). Each trapping and reference electrode was connected with a relay to the input of the operational amplifiers (OPA1 / OPA2). The shield of the voltage monitors is connected to ground. The measurement channel is connected to the cell trapping electrode.
Principle schematic of the true difference frontend (left panel) for Solartron S-1260 (right panel). Each trapping and reference electrode was connected with a relay to the input of the operational amplifiers (OPA1 / OPA2). The shield of the voltage monitors is connected to ground. The measurement channel is connected to the cell trapping electrode.

Fig.3

Multiplexer with frontend. At the left side is the receptacle for the adapter PCB with the chip. In the image, a test-chip with fixed resistors is shown. At the right side are the coaxial connectors to the Solartron S-1260 and the USB-connection for the microcontroller. The connectors in the middle of the PCB are for indicator-LED, showing the active electrode pair. A push-switch is implemented for manually advancing the position of the multiplexer. The feedback resistors are inside the red labeled boxes.
Multiplexer with frontend. At the left side is the receptacle for the adapter PCB with the chip. In the image, a test-chip with fixed resistors is shown. At the right side are the coaxial connectors to the Solartron S-1260 and the USB-connection for the microcontroller. The connectors in the middle of the PCB are for indicator-LED, showing the active electrode pair. A push-switch is implemented for manually advancing the position of the multiplexer. The feedback resistors are inside the red labeled boxes.

Fig.3

Feedback impedance Zf,1 = Zf,2 = Zf used for the transimpedances in Fig.2.
Feedback impedance Zf,1 = Zf,2 = Zf used for the transimpedances in Fig.2.

Fig.4

Magnitude and phase angle of a dilution series measured at one electrode pair (measurement and reference electrode) using the multiplexer.
Magnitude and phase angle of a dilution series measured at one electrode pair (measurement and reference electrode) using the multiplexer.

Fig.5

Magnitude and phase angle of a dilution series of PBS (phosphate buffered saline) without multiplexer. ddH2O (double distilled water) serves as low conductivity limit. For assessing the measurement and reference electrode, two measurements were necessary.
Magnitude and phase angle of a dilution series of PBS (phosphate buffered saline) without multiplexer. ddH2O (double distilled water) serves as low conductivity limit. For assessing the measurement and reference electrode, two measurements were necessary.

Fig.6

Comparison between measurements with Solartron with and without multiplexer at a dummy load (1 MΩ in parallel with a 470 pF / 1 kΩ – serial combination).
Comparison between measurements with Solartron with and without multiplexer at a dummy load (1 MΩ in parallel with a 470 pF / 1 kΩ – serial combination).

Fig.7

Measured impedance magnitude in relation to the theoretical impedance of a dummy load measured with and without the multiplexer. Obviously, the amplifiers of the frontend, connected with minimum of wiring decrease the noise especially in the low frequency region.
Measured impedance magnitude in relation to the theoretical impedance of a dummy load measured with and without the multiplexer. Obviously, the amplifiers of the frontend, connected with minimum of wiring decrease the noise especially in the low frequency region.

Fig.8

Test of the dilution series of PBS (phosphate buffered saline) using a WTW-conductometer with WTW-electrode (o) and from impedance measurement at the frequency with phase closest to zero (*). The theoretical Λm (blue line) for PBS has the limit at concentration cPBS = 0 M of 126 S/cm−2mol−1.
Test of the dilution series of PBS (phosphate buffered saline) using a WTW-conductometer with WTW-electrode (o) and from impedance measurement at the frequency with phase closest to zero (*). The theoretical Λm (blue line) for PBS has the limit at concentration cPBS = 0 M of 126 S/cm−2mol−1.

Fig.9

Normalized difference of (a) the impedance magnitude and (b) the phase angle difference between working electrodes with trapped cells and the reference ones. The red line indicates the measurement immediately after trapping the cells and the blue line was obtained 5 h after incubation. The error bars show the standard deviation of 7 electrodes. The 7th out of the 8 electrodes did not trap a cell. It is therefore not shown and omitted in the calculation.
Normalized difference of (a) the impedance magnitude and (b) the phase angle difference between working electrodes with trapped cells and the reference ones. The red line indicates the measurement immediately after trapping the cells and the blue line was obtained 5 h after incubation. The error bars show the standard deviation of 7 electrodes. The 7th out of the 8 electrodes did not trap a cell. It is therefore not shown and omitted in the calculation.

Fig.10

α-Quantiles for double sided t-test (A) magnitude of impedance and (B) phase. The red line indicated the significance level of 5% (0.975). The mean value is statistically different for frequencies with p-value above this line.
α-Quantiles for double sided t-test (A) magnitude of impedance and (B) phase. The red line indicated the significance level of 5% (0.975). The mean value is statistically different for frequencies with p-value above this line.

Fig.11

Magnitude (solid line) and phase angle (dashed line) of the applied voltage.
Magnitude (solid line) and phase angle (dashed line) of the applied voltage.

Fig.12

Magnitude of the impedance measured with multiplexed frontend (dots) and by direct attachment of the chip to the S-1260.
Magnitude of the impedance measured with multiplexed frontend (dots) and by direct attachment of the chip to the S-1260.
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Engineering, Bioengineering and Biomedical Engineering, Biomedical Electronics, Life Sciences, Biophysics, Medicine, Biomedical Engineering, Physics, Spectroscopy and Metrology
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