/covg_model_cell

KiCAD design for a COVG model cell

GNU General Public License v3.0GPL-3.0

COVG Model Cell

A model cell is a circuit of resistors (Rs) and capacitors (Cs) that emulates the electrical properties of a cell membrane, the solutions, and the electrodes used in an experiment.

Model Cell v2

Model cell photo

Board Schematic

J1 amd J9 both connect to the V1 node. C20 allows for small (2 pF) capacitive coupling from the top pool (P1, P2 after the elctrode resistance) to the microelectrode (V1).

Jumper programmable:

  • Rs (SRJ1)
  • V1 electrode resistance (REJ1)
  • P2 electrode resistance (RpcJ1)

Schematic

Bill of Materials

The board was assembled by JLCPCB using the following bill of materials.

Surface mount Rs and Cs are 1206 footprint.

The test jacks are for 0.08" (2.0 mm) diameter plugs.

An example mating pin is the 3601-1-07-21-00-00-08-0.

User's Guide

A user's guide for this model cell is here: User's guide

Fabrication

This board was fabricated and assembled by JLCPCB.

Fabrication Order #: Y11-3276043A

Assembly: SMT02308141355143-3276043A

Date: 2023/08/14

Example Schematic

The model cell is based on the schematic included in the Dagan CA-1B users manual. Model cell schematic

Future Brainstorming

A "programmable" conductance

$C_{Ma}$ and $R_{Ma}$ represet the part of the membrane with ion channels. Amplifier tests would be supported by adding a digitally controlled (i.e. a digital logic level) switch/transistor. The current of this conductance should a maximum by 10 $\mu$A. The lower the current the better which makes this difficult to do with a conventional MOSFET or BJT transistor.

Adjustable Rs and Cs

We would like to be able to test the amplifier with different values of Rs and Cs to assess the robustness to variations in these components.

Possible ideas:

  1. Pin headers with jumpers - this is included in both V1 and v2
  2. Digital potentiometer

Acknowledgments

Research reported in this repository was supported by the National Institute Of Neurological Disorders And Stroke of the National Institutes of Health under Award Number R15NS116907. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.