Optical fiber sensors for medical applications — Practical engineering considerations

Blood refractive index modelling in the visible and near infrared spectral regions

“…The blood corpuscles are mainly red blood cells (almost 99%), leucocytes (1%) and thrombocytes (>1%). The red blood cells possess the largest geometric size, as a rule, 6.2-8.2 µm, and mainly determine the optical properties of blood [1][2][3]. The quantitative and qualitative information on the blood optical properties, in particular, on the refractive index, is of great interest for many fields of biomedical studies and practical medicine, since the noninvasive or lowinvasive optical technologies become wider and wider used in diagnostics and therapy [1][2][3][4][5][6].…”

“…The red blood cells possess the largest geometric size, as a rule, 6.2-8.2 µm, and mainly determine the optical properties of blood [1][2][3]. The quantitative and qualitative information on the blood optical properties, in particular, on the refractive index, is of great interest for many fields of biomedical studies and practical medicine, since the noninvasive or lowinvasive optical technologies become wider and wider used in diagnostics and therapy [1][2][3][4][5][6]. It is well known that the optical properties of blood are determined by such physiologic and biologic parameters as haematocrit, temperature, osmolarity, saturation with oxygen or other gases, membrane rigidity of the red blood cells, and depend on the wavelength in a complex way [1,[4][5][6][7][8][9][10][11][12].…”

“…The knowledge of tissue and blood optical properties allows for determination of the optimal wavelength providing the maximal penetration depth of laser radiation. This is important for modelling the interaction between the tissue and laser radiation, e.g., in planning such clinical procedures as laser interstitial heating or photodynamic therapy, as well as in choosing the operating wavelengths of pulse oximeters widely used in different fields of medicine for monitoring the blood oxygen saturation [1][2][3][4][5][6].…”

Hybrid piezoresistive-optical tactile sensor for simultaneous measurement of tissue stiffness and detection of tissue discontinuity in robot-assisted minimally invasive surgery

“…On the other hand, optical-based sensors satisfy MR compatibility, electro-passivity, and size conditions; therefore, they make a good choice in minimally invasive surgical applications. 14,[17][18][19][20] In addition to that, possibilities for miniaturization and low-cost production are of remarkable advantages of optical-based sensors; 21,22 however, optical-based sensors are not capable of direct force measurement. On the other hand, because of the nonlinear mechanical properties of the biological tissues, establishing a simple and valid force estimation scheme from the measured deformation is cumbersome.…”

“…Researchers have developed optical tactile sensors based on three sensing principles of fiber brag grating (FBG), Fabry-Perot interferometry (FPI), and light-intensity modulation (LIM). 21,22 In an early study, Polygerinos et al 20 proposed a miniaturized optical fiber sensor for measuring the point loads at the tips of angiographic catheters; however, the proposed sensor was unable to measure the actual lateral forces acting on the tip of the catheter. In another study, Yip et al 23 developed an LIM force sensor for surgical application based on the deformation-induced intensity modulation in a set of optical fibers.…”