**1. Introduction**

Amputation is taken from the Latin terminology "amputare" meaning to cut out. It is a removal of a limb due to medical reasons such as diseases and accidents. After this, an artificial device (prosthetics) is provided to fulfill all the desired needs. A prosthesis is an artificial device that replaces a missing body part that may be lost due to any traumatic accidents or medical reasons.

In the nineteenth century, hooks and wooden limbs were used as a replacement to fulfill the supporting needs to overcome support as well as the psychological effects experienced during the time. Prosthetic arm is a biomedical device consisting of links and joints in an open or closed system, which is also a combination of electronics. Thus, there is a need for a specified prosthetic which would help in fulfilling the requirements of the patient.


#### **Table 1.**

*Types of upper-limb amputation and respective prosthesis type.*

Prosthetics also come under different categories concerning the patient's demand and desirable need. **Table 1** lists the type of amputation and their respective prosthesis type.

Controlling a prosthetic arm could be done in several ways. Some of them are by using Invasive Methods, which reflects a process in which an instrument is introduced in the human body. In such a process, electrodes are implanted inside the body, which would receive and implement the process. The other referred to as the non-invasive method. A non-invasion process does not introduce instruments into the body but uses the surface information to get its details and the desired output that is to be determined.

In the previous studies, various strategies have been practiced to monitor muscle activations all through activities, as reported by Lobo Prat et al. [1] To carry out a valuation of muscular contraction, sonomyography (SMG), mechanomyography (MMG) [2, 3], miokinemetric (MK), and electric impedance estimations are classically applied. Though muscular intentions and/or contraction are often determined using electromyography (EMG) and near-infrared spectroscopy (NIRS) [4], it allows continuous monitoring of the muscle during motor actions or rehabilitative movements. Further practices, such as ultrasonography [5] and lactate sampling, offer only a representation of the muscular status at the moment of the study, and not an effective trace in time.

Optical brain imaging is a frequently applied methodology in human-machine interaction technically acknowledged as functional near-infrared spectroscopy (fNIRS). It allows them to monitor the quantification of the relative changes in concentration of oxygenated and deoxygenated hemoglobin in tissue blood based on artificial diffuse spectroscopy. Functional neuroimaging suggests a non-invasive method of indirect as well as direct monitoring of brain activity. The hardware involved is portable hence making it easy to carry out experiments in any environment. fNIRS is a non-invasive brain imaging method including the quantification of chromophore concentration determined from the measurement of near-infrared (NIR) light attenuation or time-based changes [6]. It exploits the optical window in which the fundamental elements found in the human body typically cause no hindrance to infrared light of small wavelength range that is 700–900 nm. In addition to that, oxygenated hemoglobin (Hb) and deoxygenated-hemoglobin (deoxy-Hb) are strong absorbers of light which are the key components to translate the brain response [7]. The peculiarity in the absorption bands of deoxy-Hb and oxy-Hb permit the estimation of near changes in hemoglobin concentration by methods of estimating light attenuation at a couple of known wavelengths [8]. The reason behind choosing more than one wavelength is to take care of the isosbestic point that occurs at around 810 nm. At this value of light wavelength both the absorbing coefficients are indistinguishable [9].

Via the improved Beer-Lambert law [10], relative concentration is evaluated concerning the entire length covered by the light photon [11, 12]. Now, for an

**53**

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

incident ray of light an emitter and to detect that reflected light, a detector is positioned. The distance between them is also defined. Hence, a state of brain hemodynamic is captured. The raw light concentrations that are further transformed into hemodynamic responses by the implementation of renowned Beer-Lambert Law and further utilized for feature extraction and classification. The extracted light

Several research institutions have undertaken the design and construction of robotic arms. These structures diverge depending upon the proposed utilization of the human hand. Diverse knowledge of actuation approaches has been considered and implemented. Earlier design approaches have focused on the mechanical problems of the construction and operation of the prosthetic devices. Most of these hardware devices are controlled via methods that are not natural, such as using the contraction of muscles of the opposite arm. This research attempts to lay the foundation for a scheme that can offer functionality similar to the human arm, with

A search carried out using Web of Science engine, to review work done in this area along with the gap identification, revealed no work done so far in this field

The human arm is capable of performing seven basic motions associated with joints in the human arm. To account for transhumeral amputation, three of the main arm motions are considered i.e. one elbow and two motions affiliated with the wrist joint. These motions comprise wrist extension (WE), elbow flexion (EF), wrist supination (WS), wrist flexion (WF), elbow extension (EE), and wrist prona-

This section elaborates on the data acquisition of the defined motions. These motions were captured using The NIRsport manufactured by NIRx Technologies. It is an accessible, segmental, and robust functional near-infrared spectroscopy (fNIRS) machine that measures hemodynamic responses generated by neuroactivation of the inside brain via oxy-, deoxy-, and total hemoglobin variations in

The updated version, NIRsport-2 proposes a host prepared to implement advancements and units to meet the requirements of wide-ranging cognitive

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

intensity patterns can be viewed in **Figure 1**.

an intuitive technique of control.

**2. Materials and methods**

of study.

**Figure 1.**

*Raw fNIRS light intensity.*

tion (WP).

the cerebral cortex.

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

**Figure 1.** *Raw fNIRS light intensity.*

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

Shoulder disarticulation From shoulder below the elbow

**Types of amputation Types of prosthesis**

Transhumeral Above elbow Transradial Below elbow Transcarpal Below elbow

*Types of upper-limb amputation and respective prosthesis type.*

Prosthetics also come under different categories concerning the patient's demand and desirable need. **Table 1** lists the type of amputation and their respec-

Controlling a prosthetic arm could be done in several ways. Some of them are by using Invasive Methods, which reflects a process in which an instrument is introduced in the human body. In such a process, electrodes are implanted inside the body, which would receive and implement the process. The other referred to as the non-invasive method. A non-invasion process does not introduce instruments into the body but uses the surface information to get its details and the desired output

In the previous studies, various strategies have been practiced to monitor muscle activations all through activities, as reported by Lobo Prat et al. [1] To carry out a valuation of muscular contraction, sonomyography (SMG), mechanomyography (MMG) [2, 3], miokinemetric (MK), and electric impedance estimations are classically applied. Though muscular intentions and/or contraction are often determined using electromyography (EMG) and near-infrared spectroscopy (NIRS) [4], it allows continuous monitoring of the muscle during motor actions or rehabilitative movements. Further practices, such as ultrasonography [5] and lactate sampling, offer only a representation of the muscular status at the moment of the study, and

Optical brain imaging is a frequently applied methodology in human-machine interaction technically acknowledged as functional near-infrared spectroscopy (fNIRS). It allows them to monitor the quantification of the relative changes in concentration of oxygenated and deoxygenated hemoglobin in tissue blood based on artificial diffuse spectroscopy. Functional neuroimaging suggests a non-invasive method of indirect as well as direct monitoring of brain activity. The hardware involved is portable hence making it easy to carry out experiments in any environment. fNIRS is a non-invasive brain imaging method including the quantification of chromophore concentration determined from the measurement of near-infrared (NIR) light attenuation or time-based changes [6]. It exploits the optical window in which the fundamental elements found in the human body typically cause no hindrance to infrared light of small wavelength range that is 700–900 nm. In addition to that, oxygenated hemoglobin (Hb) and deoxygenated-hemoglobin (deoxy-Hb) are strong absorbers of light which are the key components to translate the brain response [7]. The peculiarity in the absorption bands of deoxy-Hb and oxy-Hb permit the estimation of near changes in hemoglobin concentration by methods of estimating light attenuation at a couple of known wavelengths [8]. The reason behind choosing more than one wavelength is to take care of the isosbestic point that occurs at around 810 nm. At this value of light wavelength both the absorbing

Via the improved Beer-Lambert law [10], relative concentration is evaluated concerning the entire length covered by the light photon [11, 12]. Now, for an

tive prosthesis type.

**Table 1.**

that is to be determined.

not an effective trace in time.

coefficients are indistinguishable [9].

**52**

incident ray of light an emitter and to detect that reflected light, a detector is positioned. The distance between them is also defined. Hence, a state of brain hemodynamic is captured. The raw light concentrations that are further transformed into hemodynamic responses by the implementation of renowned Beer-Lambert Law and further utilized for feature extraction and classification. The extracted light intensity patterns can be viewed in **Figure 1**.

Several research institutions have undertaken the design and construction of robotic arms. These structures diverge depending upon the proposed utilization of the human hand. Diverse knowledge of actuation approaches has been considered and implemented. Earlier design approaches have focused on the mechanical problems of the construction and operation of the prosthetic devices. Most of these hardware devices are controlled via methods that are not natural, such as using the contraction of muscles of the opposite arm. This research attempts to lay the foundation for a scheme that can offer functionality similar to the human arm, with an intuitive technique of control.

A search carried out using Web of Science engine, to review work done in this area along with the gap identification, revealed no work done so far in this field of study.
