# Focal Vibration Therapy: Vibration Parameters of Effective Wearable Devices
## 2 Materials and Methods
### Devices Tested  
Four commercially available focal vibration devices were tested: Vibracool [31], Novafon Pro [29], and two Myovolt [30] series of devices (Figure 1). The Vibracool device (Figure 1a) is marketed as a focal vibration device for pain relief. It is a battery-powered device with a single vibration motor that delivers a constant vibration. To wear the device, different styles of pouches with straps are available. Hot packs and cold packs are also available to use together with the device [31].  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Device.** & **Mode** & **Vibration Pattern** & **Manufacturer Specs.** & **Wearable** \\ \hline Vibracool & n/a & constant & - & Yes \\ \hline \multirow{4}{*}{Novafon} & Mode I at max. intensity & constant & 120 Hz & \\  & Mode II at max. intensity & constant & 60 Hz & \\  & Mode I at min. intensity & constant & 120 Hz & No \\  & Mode II at min. intensity & constant & 60 Hz & \\ \hline \multirow{4}{*}{Myovolt 3 actuator} & Mode 1 & sinusoidal & - & \\  & Mode 2 & pulsing on/off & - & Yes \\  & Mode 3 & constant & 120 Hz & \\ \hline \multirow{4}{*}{Myovolt 2 actuator} & Mode 1 & sinusoidal & - & \\  & Mode 2 & pulsing on/off & - & Yes \\ \cline{1-1}  & Mode 3 & constant & 120 Hz & \\ \hline \end{tabular}
\end{table}
Table 1: List of devices and modes used. Not all specifications have been provided by the manufacturers. Novafon frequency data [29] and Myovolt frequency data [30] are from their respective websites.  
Figure 1: Focal vibration (FV) devices that are the subject of this paper: (**a**) Vibracool, (**b**) Novafon Pro, (**c**) Myovolt two-actuator, and (**d**) Myovolt three-actuator.  
The Novafon Pro device (Figure 1b) is marketed as a general health massager. It provides focal vibration by use of a transducer, where the vibration head is directly connected to the transducer. The device is powered by mains electricity. It is advertised to have two modes: Mode I (120 Hz) and Mode II (60 Hz). The modes can be selected using a rocker switch. For each mode, intensity can be controlled by a rotating knob [29].  
Myovolt devices (Figure 1c,d) are marketed as wearable muscle relief devices, primarily for athletes. They are battery-powered. There are two models: three-actuator and two-actuator. The three-actuator models have three vibration motors, and the two-actuator models have two vibration motors, embedded together into a single flexible structure. Various straps are available for attaching them on different body parts. The Myovolt devices operate in three different modes: (1) sinusoidal, with intensity changing sinusoidally, (2) pulsing, alternating between on and off, and (3) constant vibration. The modes can be changed by pressing a mode button [30].  
Those four devices were selected for testing due to their commercial availability and use for research and clinical practice. Vibracool is commercially available. It has been used in FV therapy, and has been proven to provide pain relief [32]. In fact, it has been demonstrated to be better than transcutaneous electrical nerve stimulation (TENS) [33]. Novafon Pro is commercially available and has been used by therapists for FV therapy. It has proven to be effective [34; 35]. There are many other devices similar to Novafon Pro, but not shown, that have been used for research or clinical practice. Finally, Myovolt devices are also commercially available and have been used in research studies [36; 37; 38; 39; 40].