User's guide for Multi-threaded arrays

Required equipment to obtain recordings from Myomatrix arrays:

CAMBER provided:

• Myomatrix array  (see Figure 1)

• Non-absorbable sutures (6.0 or 8.0) for the suture-bearing arrays
• 30 g needles for muscle attachment for the insertion arrays
• Headstage compatible with the Omnetics 36-pin connector (part number NPD-36-VV-GS; A79026). We strongly recommend a bipolar headstage configuration. 
• SPI cable and data acquisition system. Refer to the CAMBER website > Getting Started > Tools and Equipment for a list of options. 

Example arrays shown below:
Figure 1a: a multi-threaded array with suture holes for muscle attachment 

Figure 1b: a multi-threaded array with insertion tails for muscle attachment

What should I do when the arrays arrive?

• All Myomatrix arrays and accessories are experimental devices and purchased as-is. While the arrays are quite robust, below are some handling recommendations when removing them from the shipping package. 
• It is best to peel the functional arrays from the box surface using the attached Omnetics connector. Blank arrays, i.e. without a connector, can be removed using blunt forceps.
• Confirm you have received the correct array design(s). Each array has the array design code etched into the polyimide on the connector end, which can be visualized under a microscope or potentially with a phone camera.

• Impedance test all devices within 30 days after delivery. Contact the CAMBER team at camber@emory.edu if impedances are in the +1MOhm range. General impedance testing instructions can be found HERE. 

Critical things to do for a successful recording: 

1. Don’t bend the array threads or handle the electrode contacts. This can break the embedded gold traces and/or compromise the contacts. 
2. The electrode contacts are on the “top side” of the Myomatrix array, i.e. on the same side as the connector. The electrode contacts on this side are black; the non-connector side is shiny. For applications where the array is placed on the muscle surface, make sure that the electrode contact side is lying against the muscle tissue.
3. Connect the headstage to the attached plug so that the words “Omnetics” are on the same side on both the headstage and the Myomatrix connector plug. 

General experimental information:

Implantation protocols for chronic EMG recording in rodents and non-human primates are available on the CAMBER website under Our Technology > Getting Started. For access to the surgical video library, contact the CAMBER team at camber@emory.edu to request login credentials. Videos include:

• Intramuscular array implantation using arrays with sutures or with the insertion tail

• Epimysial array attachment using arrays with suture holes

• Array insertion in songbirds and in non-human primates

Key usage details for all multi-threaded arrays

1. Do not autoclave. High heat or steam autoclaves damage the electrical connection between the connector and electrode. If sterilization is required, use a low-temperature alternative such as hydrogen peroxide plasma gas or ethylene oxide gas.
2. Always test electrode impedance before and after implantation. Please also measure impedances during each recording session to track performance over time. See the impedance testing procedure on the CAMBER website under Our Technology > Getting Started.
3. Reuse with care. Myomatrix arrays may be reused in acute experiments. If planning to reuse an array, avoid having the Myomatrix electrode contacts rub on tissue (e.g. lay the array on muscle targets and avoid “dragging” the electrodes over the muscle surface) to avoid damage to the electrode contacts.  Between uses, sterilize by gently applying 100% isopropyl alcohol to the electrode contacts and any portion of the array that contacted the animal.