A Real-Time Wearable Electromyography Measurement System for Small Animals

Summary

A protocol is presented for the installation and preparation of intramuscular electrodes, along with an animal-mountable, miniaturized measurement device for electromyography (EMG) analysis in locomotion studies. This system enables the wireless transmission of real-time EMG data for investigating locomotion recovery in stroke model rats.

Abstract

The intramuscular electromyography (EMG) measurement method for experimental animals has been implemented in various ways. Among these methods, tethering cables to external measurement devices can restrict the movement of experimental animals, while implantable devices may cause unwanted side effects due to the constant presence of a device with considerable size and weight. To address these issues, we propose a low-cost, wireless, detachable EMG measurement system and experimental procedure. This article focuses on the surgical installation of intramuscular wire electrodes with small connectors and the development of the wireless system. Notably, in this system, only the wire electrodes are inserted into the animal's body. Using this system, EMG measurements can be easily performed by attaching the circuit system to a connector installed on the animal's back, with real-time monitoring achievable on a laptop. The proposed method is explained in a detailed, step-by-step manner, followed by a demonstration involving the insertion of intramuscular electrodes into the hindlimbs of a rat. A treadmill experiment is conducted for a locomotion study, and the resulting electrophysiological signals are subsequently obtained and analyzed.

Introduction

Electromyography involves recording electrical potentials generated by muscle fibers during contraction. These properties are determined by neural activation signals sent from motor neurons to individual muscles. EMG is widely used in rehabilitation, motor, brain, and nerve-related studies, and the measurement methods can be broadly classified into surface EMG (sEMG) and intramuscular EMG (iEMG)¹. Surface electrodes offer several advantages, particularly in wearable applications, as they are non-invasive and require a simple preparation process². In implanted sEMG, the surgical process is simpler compared to iEMG, where ....

Protocol

Approval of all ethical and experimental procedures and protocols was granted by the Institutional Animal Care and Use Committee under Application No. CGU1-2021-IA0041. A 7-week-old male Sprague-Dawley rat was used in this study. The details of the reagents and equipment are listed in the Table of Materials.

1. Animal preparation

1. Prepare rats at the age of 7 weeks. For safety, house rats of similar weights together, with a maximum of three rats per.......

Discussion

This work presents an electromyography (EMG) acquisition system that is small, easy to implement, low-cost, and wireless. The system effectively prevents signal degradation caused by cables, as it does not rely on any wired external measurement equipment. By mounting the connector on the back instead of the head, the surgical process becomes significantly easier, reducing the risk of complications. This setup also minimizes the chances of the platform bumping into side walls, which can lead to signal artifacts. Additiona.......

Materials

Name	Company	Catalog Number	Comments
0.2 mm thickness nickel plate	Any available vender
3D-printing filament	cubicon	A-100
7 weeks old RAT	JABIO	SD (DBL) [7W M]
Adhesive	Okong	1028453	for securing shield
ANT1	Johanson Technology Inc.	2450AT07A0100001T
C1, C15, C16, C20	Vishay	1n	0201(0603)metric
C10, C13	Vishay	100p	0201(0603)metric
C11, C12	Vishay	4p	0201(0603)metric
C14, C19	Vishay	0.39n	0201(0603)metric
C2, C17	Vishay	22n	0201(0603)metric
C3, C5, C6	Vishay	0.1u	0201(0603)metric
C4, C18	Vishay	2.2u	0201(0603)metric
C7	Vishay	4.7u	0402(1005)metric
C8, C21	Vishay	1u	0201(0603)metric
C9	Vishay	1p	0201(0603)metric
Cage	JEUNG DO B&P	JD-C-02
Clean cloth	kimberly	41112
Connector accessory	Harwin	M20-1060400	Plastic housing
Connector accessory	Harwin	M20-1180042	Metal part
Electric hair clipper	Buzz	RFC-928
Heat gun	QUICK	861DW
IC1, IC3	Analog Device	AD8232	For EMG measurement AFE
IC2	Nordic semiconductor	nRF52832-CIAA
Isoflurane	Hana Pharm	657801261
L1	Vishay	3.3n	0201(0603)metric
Li-po battery	TheHan	TW402025	13 mm *10 mm * 4 mm, 30mAh
Pin header	Harwin	M22-2530505
R1, R2, R9, R10, R13, R14, R21, R22	Vishay	10M	0201(0603)metric
R11, R23	Vishay	100k	0201(0603)metric
R12, R24	Vishay	1M	0201(0603)metric
R3, R4, R5, R7, R15, R16, R17, R19	Vishay	180k	0201(0603)metric
R6, R18	Vishay	160k	0201(0603)metric
R8, R20	Vishay	768k	0201(0603)metric
Solder wire	Alpha metal	SACX0307
Soldering iron	Hakko	FX-951
Stainless steel wires coated with Teflon	A-M Systems	793200
Suture needle	AILEE	301289
Suture wire	Ethicon	604G
Treadmill	Daejong Bio	DJ2-243
U1	Torex Semiconductor	XC6204B332DR-G
Y1	Murata Electronics	XRCTD32M000N1P1AR0