Electric and Magnetic Field Devices for Stimulation of Biological Tissues

Summary

This protocol describes the step-by-step process to build both electrical and magnetic stimulators used to stimulate biological tissues. The protocol includes a guideline to simulate computationally electric and magnetic fields and manufacture of stimulator devices.

Abstract

Electric fields (EFs) and magnetic fields (MFs) have been widely used by tissue engineering to improve cell dynamics such as proliferation, migration, differentiation, morphology, and molecular synthesis. However, variables such stimuli strength and stimulation times need to be considered when stimulating either cells, tissues or scaffolds. Given that EFs and MFs vary according to cellular response, it remains unclear how to build devices that generate adequate biophysical stimuli to stimulate biological samples. In fact, there is a lack of evidence regarding the calculation and distribution when biophysical stimuli are applied. This protocol is focused on the design and manufacture of devices to generate EFs and MFs and implementation of a computational methodology to predict biophysical stimuli distribution inside and outside of biological samples. The EF device was composed of two parallel stainless-steel electrodes located at the top and bottom of biological cultures. Electrodes were connected to an oscillator to generate voltages (50, 100, 150 and 200 Vp-p) at 60 kHz. The MF device was composed of a coil, which was energized with a transformer to generate a current (1 A) and voltage (6 V) at 60 Hz. A polymethyl methacrylate support was built to locate the biological cultures in the middle of the coil. The computational simulation elucidated the homogeneous distribution of EFs and MFs inside and outside of biological tissues. This computational model is a promising tool that can modify parameters such as voltages, frequencies, tissue morphologies, well plate types, electrodes and coil size to estimate the EFs and MFs to achieve a cellular response.

Introduction

EFs and MFs have been shown to modify cell dynamics, stimulating proliferation and increasing synthesis of the main molecules associated with the extracellular matrix of tissues¹. These biophysical stimuli can be applied in different ways by using specific settings and devices. Regarding the devices to generate EFs, direct coupling stimulators use electrodes that are in contact with biological samples in vitro or implanted directly into tissues of patients and animals in vivo²; however, there are still limitations and deficiencies that include insufficient biocompatibility by the electrodes in contact, changes in the pH ....

Protocol

1. Simulation of EFs and MFs

NOTE: Simulation of EFs and MFs was performed in COMSOL Multiphysics.

1. Select an axisymmetric 2D configuration to represent both domains electric and magnetic.
2. In the physic configuration, select either the Electric Current interface to compute EFs in parallel electrodes or the Magnetic Field interface to compute MFs around coils.
3. In the study configuration, select Frequency Domain to.......

Discussion

Treatments used to heal different pathologies that affect human tissues are pharmacological therapies³² or surgical interventions³³, which seek to relieve pain locally or replace affected tissues with explants or transplants. Recently, autologous cell therapy has been proposed as an alternative therapy to treat injured tissues, where cells are isolated from patient and expanded, through in vitro techniques, to be implanted at the site of the injury³⁴.......

Materials

Name	Company	Catalog Number	Comments
Electrical stimulator
Operational amplifier	Motorola	LF-353N	---- Quantity: 1
Resistors	----	----	22 kΩ Quantity: 1
Resistors	----	----	10 kΩ Quantity: 3
Resistors	----	----	2.6 kΩ Quantity: 2
Resistors	----	----	2.2 kΩ Quantity: 1
Resistors	----	----	1 kΩ Quantity: 1
Resistors	----	----	220 Ω Quantity: 2
Resistors	----	----	22 Ω Quantity: 5
Resistors	----	----	10 Ω Quantity: 1
Resistors	----	----	6.8 Ω Quantity: 1
Resistors	----	----	3.3 Ω Quantity: 2
Polyester capacitors	----	----	1 nF Quantity: 2
Polyester capacitors	----	----	100 nF Quantity: 1
VHF Band Amplifier Transistor JFET	Toshiba	2SK161	---- Quantity: 1
Power transistor BJT NPN	Mospec	TIP 31C	---- Quantity: 1
Zener diode	Microsemi	1N4148	---- Quantity: 1
Switch	Toogle Switch	SPDT - T13	---- Quantity: 3
Toroidal ferrite core	Caracol	----	T*22*14*8 Quantity: 1
Cooper wire	Greenshine	----	AWG – 24 Quantity: 1
Relimate header with female housing	ADAFRUIT	----	8 pin connectors Quantity: 1
Relimate header with female housing	ADAFRUIT	----	2 pin connectors Quantity: 1
Female plug terminal connector	JIALUN	----	4mm Lantern Plugs (Plug + Socket) 15 A Quantity: 1
Aluminum Heat Sink	AWIND	----	For TIP 31C transistor Quantity: 1
Led	CHANZON	----	5 mm red Quantity: 1
Integrated circuit socket connector	Te Electronics Co., Ltd.	----	Double row 8-pin DIP Quantity: 1
3 pin connectors set	STAR	----	JST PH 2.0 Quantity: 3
2 pin screw connectors	STAR	----	For PCB Quantity: 1
3 pin screw connectors	STAR	----	For PCB Quantity: 1
Banana connector test lead	JIALUN	----	P1041 - 4 mm - 15 A Quantity: 7
Bullet connectors to banana plug charge lead	JIALUN	----	4 mm male-male/female-female adapters - 15 A Quantity: 1
Case	----	----	ABS Quantity: 1
Electrodes	----	----	Stainless – steel Quantity: 2
Electrode support	----	----	Teflon Quantity: 2
Printed circuit board			Quantity: 1
Magnetic stimulator
Cooper wire	Greenshine	----	AWG – 18 Quantity: 1
AC power plugs	----	----	120 V AC – 60 Hz Quantity: 1
Banana female connector test lead	JIALUN	----	1Set Dual Injection - 4 mm – 15 A Quantity: 2
Banana male connector test lead	JIALUN	----	1Set Dual Injection - 4 mm 15 A Quantity: 1
Cell culture well plate support	----	----	PMMA Quantity: 1
Fuse	Bussmann	2A	---- Quantity: 1
Transformer	----	----	1A – 6 V AC Quantity: 1
Tube	----	----	PVC Quantity: 1
Variable rheostat	MCP	BXS150	10 Ω Quantity: 1
General equipment
Digital dual source	PeakTech	DG 1022Z	2 x 0 - 30 V / 0 - 5 A CC / 5 V / 3 A fijo Quantity: 1
Digital Oscilloscope	Rigol	DS1104Z Plus	100 MHz, bandwidth, 4 channels Quantity: 1
Digital multimeter	Fluke	F179	Voltage CC – CA (1000 V). Current CC – CA 10 A. Frequency 100 kHz Quantity: 1