*2.2.1 Preparation*

The specially designed fNIRS headset i.e. Easycap by NIRx technologies follows the international standard of source-detector separations i.e. 3 cm [15–24]. After the subject wears the cap, the optodes are calibrated. The result of this calibration can be analyzed as in **Figure 3**. The faulty setting is shown in **Figure 3(b)**. The boxes represent optodes. The color bar indicates if the optodes are in contact with the scalp or not and hence the colors are assigned. The white color depicts no connection between scalp and optodes. The red color indicated that the connection between the scalp and optode is critical, i.e. it needs to be adjusted. Sometimes hair comes as a hindrance and just by plugging the optode again in the cap would help establish a better connection. If the issue is not resolved by then, a clinical gel (EASYCAP Supervisc, high-viscosity electrolyte-gel) is used to make sure no hair absorbed the light. The gel is rated healthy and is safe to use with optodes. The yellow color indicates that the connection is acceptable. The signals can be acquired. In this scenario, the machine conditions are calibrated by the machine itself. The machine adds a gain factor to the optodes where the connection is acceptable and it


**55**

*2.2.2 Acquisition*

**Figure 3.**

**Figure 2.**

*Generic methodology.*

that were identified by fNIRS.

*Control of a Prosthetic Arm Using fNIRS, a Neural-Machine Interface*

is saved in conditions file which is used in signal processing later. The green color shows that the optodes are perfectly placed on the head surface and an excellent connection is established for data acquisition. It can be analyzed in **Figure 3(a)**.

*Visual representation of optode settings. The perfect setting is illustrated in (a) meanwhile the faulty optode* 

*settings are shown in (b). The color bar on the right side represents the signal quality class.*

When the optodes are aligned, signal acquisition is started. The test strategy was segmented into training and testing. The subjects were asked to complete six tasks

A comfortable chair was set up roughly 100 cm away from the subjects so that the motion cues are visible to them while the screen backlight does not interfere with the optical sensors [25–38]. This environment was set up for signal extraction. The Easycap was prepared in advance to minimize the time consumption during the optode placement process. Yet some of the detectors/sources had to be optimized during the calibration process by fixing hair via gel. The session commenced with an undeveloped span of 30 seconds to create a reference point. Later the screen indicated the participants to perform one of six definite tasks the training was

*DOI: http://dx.doi.org/10.5772/intechopen.93565*

#### **Table 2.** *Demographic characteristics of amputed subjects.*

*Control of a Prosthetic Arm Using fNIRS, a Neural-Machine Interface DOI: http://dx.doi.org/10.5772/intechopen.93565*

#### **Figure 2.** *Generic methodology.*

*Data Acquisition - Recent Advances and Applications in Biomedical Engineering*

participated in the study. Their demographics are given in **Table 2**.

The generic methodology can be seen in **Figure 2**.

the development of a wearable and portable system.

**2.1 Sample**

Helsinki [14].

*2.2.1 Preparation*

**2.2 fNIRS data acquisition**

neuroscience applications. The major advantage of this device is that it is designed to work in a rugged environment and also this device is portable. This feature aids in

A total of 15 healthy subjects were engaged who were reported to be righthand dominant males having a mean age of 30 with a standard deviation of 4. Righthanders had been pursued to confine any dissimilarities in the hemodynamic responses because of the hemispheric domination difference [13]. All participants were chosen wisely as no one of the selected subjects had engaged in any prior study associated with brain signal acquisition experiments. None was accounted for to have a past filled with any mental, neurological, or visual affliction. Every one of them had an ordinary vision, and all signed and agreed to a composed consent after being briefed in detail regarding the test procedure. Three amputee subjects also

Trials employing fNIRS were permitted by the Air University Human Research Ethics Committee (HREC). These research experiments were held regarding ethical standards dictated by the world medical association in the recent declaration of

The specially designed fNIRS headset i.e. Easycap by NIRx technologies follows the international standard of source-detector separations i.e. 3 cm [15–24]. After the subject wears the cap, the optodes are calibrated. The result of this calibration can be analyzed as in **Figure 3**. The faulty setting is shown in **Figure 3(b)**. The boxes represent optodes. The color bar indicates if the optodes are in contact with the scalp or not and hence the colors are assigned. The white color depicts no connection between scalp and optodes. The red color indicated that the connection between the scalp and optode is critical, i.e. it needs to be adjusted. Sometimes hair comes as a hindrance and just by plugging the optode again in the cap would help establish a better connection. If the issue is not resolved by then, a clinical gel (EASYCAP Supervisc, high-viscosity electrolyte-gel) is used to make sure no hair absorbed the light. The gel is rated healthy and is safe to use with optodes. The yellow color indicates that the connection is acceptable. The signals can be acquired. In this scenario, the machine conditions are calibrated by the machine itself. The machine adds a gain factor to the optodes where the connection is acceptable and it

Patient ID A1 A2 A3 Gender Male Male Male Age 23 32 42 Amputated side Right Left Right Residual length (cm) 14 18 10 Time of amputation (months) 7 24 145

**54**

**Table 2.**

*Demographic characteristics of amputed subjects.*

**Figure 3.**

*Visual representation of optode settings. The perfect setting is illustrated in (a) meanwhile the faulty optode settings are shown in (b). The color bar on the right side represents the signal quality class.*

is saved in conditions file which is used in signal processing later. The green color shows that the optodes are perfectly placed on the head surface and an excellent connection is established for data acquisition. It can be analyzed in **Figure 3(a)**.
