Flexible silicon sensors for diffuse reflectance spectroscopy of tissue

Abstract

Diffuse reflectance spectroscopy (DRS) is being used in exploratory clinical applications such as cancer margin assessment on excised tissue. However, when interrogating nonplanar tissue anomalies can arise from non-uniform pressure. Herein is reported the design, fabrication, and test of flexible, thin film silicon photodetectors (PDs) bonded to a flexible substrate designed for use in conformal DRS. The PDs have dark currents and responsivities comparable to conventional Si PDs, and were characterized while flat and while flexed at multiple radii of curvature using liquid phantoms mimicking adipose and malignant breast tissue. The DRS and nearest neighbor crosstalk results were compared with Monte Carlo simulations, showing good agreement between simulation and experiment. . 11. G. Zonios, J. Bykowski, and N. Kollias, "Skin melanin, hemoglobin, and light scattering properties can be quantitatively assessed in vivo using diffuse reflectance spectroscopy," J. Invest. Dermatol. 117(6), 1452-1457 (2001). 12. A. Garcia-Uribe, J. Zou, M. Duvic, J. H. Cho-Vega, V. G. Prieto, and L. V. Wang, "In vivo diagnosis of melanoma and nonmelanoma skin cancer using oblique incidence diffuse reflectance spectrometry," Cancer Res. 72(11), 2738-2745 (2012). 13. N. Subhash, J. R. Mallia, S. S. Thomas, A. Mathews, P. Sebastian, and J. Madhavan, "Oral cancer detection using diffuse reflectance spectral ratio R540/R575 of oxygenated hemoglobin bands," J. Biomed. Opt. 11(1), 014018 and N. Ramanujam, "Performance metrics of an optical spectral imaging system for intra-operative assessment of breast tumor margins," Opt.

Nanotechnology: a promising method for oral cancer detection and diagnosis

“…The reflected light is greatly affected by cytologic and morphologic changes during epithelial tissue cancerization, including nuclear size, collagen content, extracellular matrix structure, epithelial thickness, and blood flow variation [ 28 , 96 ]. It is reported that recording diffuse reflectance images can help to determine surgical margins and is a useful tool to differentiate normal mucosa, OPMD, and oral cancer [ 96 – 98 ].…”

Laser‐Patterned Graphite‐Based Strain and Temperature Sensor on Disposable Paper Cup

“…[1][2][3][4] In recent years, the application of flexible sensors becomes more and more widespread, such as health monitoring devices, [5][6][7][8] energy harvesting devices, [9,10] and flexible displays. [11,12] Flexible sensors are usually made by patterning electronic materials (e.g., carbon nanotubes, [13,14] graphene nanosheets, [15] graphite particles, [16] gold nanowires, [17] metal nanoparticles [18] and silicon [19] ) on flexible supporting substrates (e.g., silicone elastomers, [20] polyimide, [21] paper, [22] hydrogels [23,24] and textiles. [25] However, flexible sensors still rely on expensive complicated fabrication processes with costly fabrication facilities, which will increase the fabrication cost and disposable value.…”

“…[25] However, flexible sensors still rely on expensive complicated fabrication processes with costly fabrication facilities, which will increase the fabrication cost and disposable value. [13][14][15][16][17][18][19][20][26][27][28][29][30][31] For example, laser-induced graphene (LIG) foams were used to make the flexible strain sensors by irradiating polyimide (PI) or polydimethylsiloxane (PDMS) using laser, [26][27][28]31] which can be fabricated quickly on the 3D surface at low cost. However, PI and PDMS are not biodegradable and not good for disposability.…”

Methods of extraction of optical properties from diffuse reflectance measurements of ex-vivo human colon tissue using thin film silicon photodetector arrays

“…However, the reliance of conventional DRS systems on optical fibers for reflectance collection limits system performance, limits scalability, and constrains the design options. In contrast, custom thin film silicon (Si) photodetectors (PDs) offer a high performance, scalable, and highly customizable alternative to optical fibers for reflectance collection in tissue DRS applications [14][15][16][17][18]. Si PDs improve performance over optical fibers since they have higher numerical apertures (NAs) and collect light from a larger fraction of the probe surface, they are highly scalable due to Si manufacturing technology, they can be geometrically optimized for specific applications, they can be implemented on a variety of substrates, including flexible or conformal, and they can be implemented in the instrument channel or as an attachment to an endoscope.…”