B.1 Fabrication Processes of Multilayer Structure TSP
B.1.3 Signal Processing
69
adjacent electrodes are used as RX and TX repetitively shown in the Figure 50 (a), considerable amounts of the electric fields between them now can reach the finger, more specifically the branches of radial or ulnar arteries in the finger as shown in Figure 50 (b).
70
Figure 51 (a) The capacitance-time graph when finger touches the electrode. The green dashed line encloses the signal processing results for the oscillating portion of the capacitance measured within a time interval of ~250 s, and the blue dashed line encloses the corresponding result over the time interval of ∼10 s. (b), (d) show the normalized capacitance after band pass filtering (0.5–3.0Hz), and (c), (e) show the frequency spectrum obtained by the subsequent fast Fourier transform (FFT). The frequency spectrum of a capacitance signal measured for another person by the same signal processing procedure.
71
B.2 Extraction of Heart-Rate with a Protective Layer Covering High-Resolution Top Electrodes For the real device implementation, there always be required protective layer which reduces the transmitted electric field. The other thing that should be considered is penetration depth which compensate physically extended length that electric field should be reach. One suggestion to overcome penetration depth problem is enlarging the gap between TX and RX. However, the enlargement of the gap makes it impossible to apply practical TSP which require higher touch resolution. Alternative is changing TX and RX as nonadjacent electrodes. Figure 52 (a) shows an example of operation schematic to measure heartbeat signal. The TX and RX are arranged at intervals of two spaces, and the electrodes between the TX and RX are grounded. The electric field distribution when finger touched in the operation with protective glass is shown in Figure 52 (b).
Figure 52 (c), (d), (e) show the signal processing of the heartbeat signal. Here, the mutual capacitance between the two nonadjacent electrodes decreases over all because the electric field loss to the finger become more dominant that the dielectric effect by the finger. This is originated in the dielectric constant of glass is 5 times larger than that of air. Nonetheless, the clear oscillation in the measured mutual capacitance is observed, which indicates the cyclic modulation of the dielectric constant of finger originating from the periodic blood flow synchronized with heartbeat. As in the previous method, 0.5 ~ 3 Hz of band pass filter was applied (Figure 52 (d)), and FFT was adopted (Figure 52 (e)). The amplitude of oscillation was measured about 3 fF. In the FFT result, the clear peak occurred near the 82.54 bpm, while the directly counting heartbeat on the wrist was measured in 84 bpm. The heartrates were measured in various conditions. Figure 52 (f), (g), (h) show the trend of capacitively measured heartrates accordance with the directly measured heartrates. We have also found that heartrates were measured well even when exercise increases heartrate to about 120 rpm. Furthermore, when the protective layer was replaced by other material such as 300 um thickness of PDMS, the extracted heartrates are still coincident with directly measured heartrates.
To sum up, it has experimentally proved that heart rate can be detected in conventional capacitive type TSPs by tracing the time-dependent capacitance between two top adjacent electrodes instead of top and bottom electrodes. Periodic changes in the effective dielectric constant of fingers due to periodic blood flow synchronized with the heart cycle were found to produce a regular vibration pattern when measured capacitance. With the help of the FFT, the heart rate can be reliably extracted to match compare to the heart beats in the wrist that were actually counted. Our work can extend its use to real-time health monitoring by providing an easy way to apply heart rate detection function to existing TSPs.
72
Figure 52 Schematic view of (a) configuration of electrode/circuit and (b) the working principle of TSP for heart-rate sensing with cover layer. The red lines indicate the electric field lines lost originated in the finger and the blue lines represent the electric field lines penetrating the finger. (c) Capacitance change by the touch of finger, (d) normalized capacitance after the band pass filtering process (0.5–3.0 Hz), and (e) frequency spectrum obtained by FFT. Frequency spectra of the capacitance data measured (f) for another person and (g) after exercise. The values inside the parentheses of (e), (f), and (g) are the heart-rates that is directly counted on the wrist. (h) Correlation between directly-counted and capacitively-measured heart-rates for without cover layer, glass cover layer, and PDMS cover layer.
73
References
1. Saks, N., S. Mani, and A.J.A.P.L. Agarwal, Interface trap profile near the band edges at the 4H-SiC/SiO 2 interface. 2000. 76(16): p. 2250-2252.
2. Harris, G.L., Properties of silicon carbide. 1995: Iet.
3. Weitzel, C.E., et al., Silicon carbide high-power devices. 1996. 43(10): p. 1732-1741.
4. Zhao, J.H., et al., Silicon carbide schottky barrier diode. 2005. 15(04): p. 821-866.
5. Saks, N. and A.J.A.P.L. Agarwal, Hall mobility and free electron density at the SiC/SiO 2 interface in 4H–SiC. 2000. 77(20): p. 3281-3283.
6. Tsui, B.-Y., et al., Schottky barrier height modification of metal/4H-SiC contact using ultrathin TiO2 insertion method. 2014. 53(4S): p. 04EP10.
7. Nye, J.F., Physical properties of crystals: their representation by tensors and matrices. 1985:
Oxford university press.
8. Bernardini, F., V. Fiorentini, and D.J.P.R.B. Vanderbilt, Spontaneous polarization and piezoelectric constants of III-V nitrides. 1997. 56(16): p. R10024.
9. Choi, G., et al., Schottky barrier modulation of metal/4H-SiC junction with thin interface spacer driven by surface polarization charge on 4H-SiC substrate. 2015. 107(25): p. 252101.
10. Qteish, A., V. Heine, and R.J.P.R.B. Needs, Polarization, band lineups, and stability of SiC polytypes. 1992. 45(12): p. 6534.
11. Davydov, S.Y. and A.J.P.o.t.S.S. Troshin, Estimates of the spontaneous polarization in silicon carbide. 2007. 49(4): p. 759-761.
12. Sze, S.M. and K.K. Ng, Physics of semiconductor devices. 2006: John wiley & sons.
13. Nicholls, J., et al., Description and verification of the fundamental current mechanisms in silicon carbide Schottky barrier diodes. 2019. 9(1): p. 1-9.
14. Bethe, H.A., Theory of the boundary layer of crystal rectifiers, in Semiconductor Devices:
Pioneering Papers. 1991, World Scientific. p. 387-399.
15. Roccaforte, F., et al., Richardson’s constant in inhomogeneous silicon carbide Schottky contacts. 2003. 93(11): p. 9137-9144.
16. Sharma, B., Metal-semiconductor Schottky barrier junctions and their applications. 2013:
Springer Science & Business Media.
17. Bozhkov, V., N. Torkhov, and A.J.J.o.A.P. Shmargunov, About the determination of the Schottky barrier height with the CV method. 2011. 109(7): p. 073714.
18. Park, K.-B., et al., Effect of inclined quantum wells on macroscopic capacitance-voltage response of Schottky contacts: Cubic inclusions in hexagonal SiC. 2005. 86(22): p. 222109.
19. Afanas' ev, V.V., Internal photoemission spectroscopy: principles and applications. 2010:
74 Elsevier.
20. Helman, J. and F.J.P.R.B. Sanchez-Sinencio, Theory of internal photoemission. 1973. 7(8): p.
3702.
21. Fowler, R.H.J.P.r., The analysis of photoelectric sensitivity curves for clean metals at various temperatures. 1931. 38(1): p. 45.
22. Kar, J.P., et al., Effect of annealing on DC sputtered aluminum nitride films. 2005. 198(1-3): p.
64-67.
23. Kim, H., H.J. Yun, and B.J.J.O. Choi, Investigation of fast and slow traps in atomic layer deposited AlN on 4H-SiC. 2019. 184: p. 527-532.
24. Seppänen, H., et al., Aluminum nitride transition layer for power electronics applications grown by plasma-enhanced atomic layer deposition. 2019. 12(3): p. 406.
25. Horita, M., et al., 4H-SiC MISFETs With 4H-AlN Gate Insulator Isopolytypically Grown on 4H- SiC $(11\bar {2} 0) $. 2014. 35(3): p. 339-341.
26. Zetterling, C.-M., et al. SiC MISFETs with MBE-grown AlN gate dielectric. in Materials Science Forum. 2000. Trans Tech Publications Ltd., Zurich-Uetikon, Switzerland.
27. Khosa, R.Y., et al., Electrical properties of 4H-SiC MIS capacitors with AlN gate dielectric grown by MOCVD. 2019. 153: p. 52-58.
28. Reddy, V.P.K. and S.J.M.S.i.S.P. Kotamraju, Improved device characteristics obtained in 4H- SiC MOSFET using high-k dielectric stack with ultrathin SiO2-AlN as interfacial layers. 2018.
80: p. 24-30.
29. Ponce, F., C. Van de Walle, and J.J.P.R.B. Northrup, Atomic arrangement at the AlN/SiC interface. 1996. 53(11): p. 7473.
30. Strak, P., et al., Polarization and polarization induced electric field in nitrides-critical evaluation based on DFT studies. 2011.
31. Sereni, J.G.R., Reference module in materials science and materials engineering. 2016.
32. Cheng, Z., et al., Experimental observation of high intrinsic thermal conductivity of AlN. 2020.
4(4): p. 044602.
33. Xu, R.L., et al., Thermal conductivity of crystalline AlN and the influence of atomic-scale defects. 2019. 126(18): p. 185105.
34. Pradhan, S., et al. Wear characteristics of Al-AlN composites produced in-situ by nitrogenation.
in IOP Conference Series: Materials Science and Engineering. 2015. IOP Publishing.
35. Hashim, U., S. Shaari, and B.Y. Majlis. Characterization of thin oxide removal by rapid thermal annealing treatment. in ICSE'98. 1998 IEEE International Conference on Semiconductor Electronics. Proceedings (Cat. No. 98EX187). 1998. IEEE.
36. Chen, Z., et al., MOS characteristics of C-face 4H-SiC. 2010. 39(5): p. 526-529.
37. Afanas' ev, V.J.M.e., Electronic properties of SiO2SiC interfaces. 1999. 48(1-4): p. 241-248.
75
38. Sigmund, P.J.P.r., Theory of sputtering. I. Sputtering yield of amorphous and polycrystalline targets. 1969. 184(2): p. 383.
39. Williams, P.J.S.S., The sputtering process and sputtered ion emission. 1979. 90(2): p. 588-634.
40. Kluth, O., et al., Comparative material study on RF and DC magnetron sputtered ZnO: Al films.
2006. 502(1-2): p. 311-316.
41. Homma, Y. and S.J.J.o.T.E.S. Tsunekawa, Planar deposition of aluminum by RF/DC sputtering with RF bias. 1985. 132(6): p. 1466.
42. Cremer, R., et al., Comparative characterization of alumina coatings deposited by RF, DC and pulsed reactive magnetron sputtering. 1999. 120: p. 213-218.
43. Gillinger, M., et al., Impact of annealing temperature on the mechanical and electrical properties of sputtered aluminum nitride thin films. 2015. 117(6): p. 065303.
44. Wu, S. and R.J.S.-S.E. Campbell, Au SiC Schottky barrier diodes. 1974. 17(7): p. 683-687.
45. Raghunathan, R., D. Alok, and B.J.I.E.D.L. Baliga, High voltage 4H-SiC Schottky barrier diodes. 1995. 16(6): p. 226-227.
46. Itoh, A., T. Kimoto, and H.J.I.E.D.L. Matsunami, High performance of high-voltage 4H-SiC Schottky barrier diodes. 1995. 16(6): p. 280-282.
47. Nakamura, T., et al., A 4.15 kV 9.07-m/spl Omega//spl middot/cm/sup 2/4H-SiC Schottky- barrier diode using Mo contact annealed at high temperature. 2005. 26(2): p. 99-101.
48. Östling, M., R. Ghandi, and C.-M. Zetterling. SiC power devices—Present status, applications and future perspective. in 2011 IEEE 23rd International Symposium on Power Semiconductor Devices and ICs. 2011. IEEE.
49. Coss, B., et al., Near band edge Schottky barrier height modulation using high-κ dielectric dipole tuning mechanism. 2009. 95(22): p. 222105.
50. Dhar, S., et al., Interface passivation for silicon dioxide layers on silicon carbide. 2005. 30(4):
p. 288-292.
51. Achtziger, N., et al., Hydrogen passivation of silicon carbide by low-energy ion implantation.
1998. 73(7): p. 945-947.
52. Gülen, Y., et al., Schottky barrier height modification in Au/n-type 6H–SiC structures by PbS interfacial layer. 2011. 88(2): p. 179-182.
53. Lee, S.-K., C.-M. Zetterling, and M.J.J.o.e.m. Östling, Schottky barrier height dependence on the metal work function for p-type 4H-silicon carbide. 2001. 30(3): p. 242-246.
54. Robertson, J.J.J.o.V.S., et al., Band offsets and work function control in field effect transistors.
2009. 27(1): p. 277-285.
55. Coss, B.E., et al., Contact resistance reduction to FinFET source/drain using novel dielectric dipole Schottky barrier height modulation method. 2011. 32(7): p. 862-864.
56. Kaufmann, I.R., et al., Schottky barrier height of Ni/TiO2/4H-SiC metal-insulator-
76 semiconductor diodes. 2015. 30(12): p. 125002.
57. Afanas’ Ev, V. and A.J.J.o.a.p. Stesmans, Internal photoemission at interfaces of high-κ insulators with semiconductors and metals. 2007. 102(8): p. 5.
58. Choyke, W. and L.J.P.R. Patrick, Higher absorption edges in 6 H SiC. 1968. 172(3): p. 769.
59. Connelly, D., et al., Fermi-level depinning for low-barrier Schottky source/drain transistors.
2006. 88(1): p. 012105.
60. Hu, J., et al., Impact of fixed charge on metal-insulator-semiconductor barrier height reduction.
2011. 99(25): p. 252104.
61. Coss, B.E., et al., Measurement of Schottky barrier height tuning using dielectric dipole insertion method at metal–semiconductor interfaces by photoelectron spectroscopy and electrical characterization techniques. 2013. 31(2): p. 021202.
62. Wager, J.F. and J.J.J.o.A.P. Robertson, Metal-induced gap states modeling of metal-Ge contacts with and without a silicon nitride ultrathin interfacial layer. 2011. 109(9): p. 094501.
63. Huang, L., et al., Modulating Schottky barrier of metal/p-type 4H-SiC by thin insulator TiO2 layer intercalation. 2020. 127(22): p. 225301.
64. Lin, L., J. Robertson, and S.J.M.e. Clark, Shifting Schottky barrier heights with ultra-thin dielectric layers. 2011. 88(7): p. 1461-1463.
65. Lin, J.-Y.J., et al., Increase in current density for metal contacts to n-germanium by inserting TiO 2 interfacial layer to reduce Schottky barrier height. 2011. 98(9): p. 092113.
66. Hu, J., K.C. Saraswat, and H.-S.P.J.J.o.A.P. Wong, Metal/III-V Schottky barrier height tuning for the design of nonalloyed III-V field-effect transistor source/drain contacts. 2010. 107(6): p.
063712.
67. Umeda, T., et al., SiC MOS Interface States: Difference between Si face and C face. 2013. 58(7):
p. 55.
68. Potbhare, S., et al., Numerical and experimental characterization of 4 H-silicon carbide lateral metal-oxide-semiconductor field-effect transistor. 2006. 100(4): p. 044515.
69. Noborio, M., et al., 4H‐SiC MISFETs with nitrogen‐containing insulators. 2009. 206(10): p.
2374-2390.
70. Modic, A., et al., Nitrogen Plasma Processing of SiO 2/4H-SiC Interfaces. 2014. 43(4): p. 857- 862.
71. Chung, G., et al., Effect of nitric oxide annealing on the interface trap densities near the band edges in the 4H polytype of silicon carbide. 2000. 76(13): p. 1713-1715.
72. Deng, S., et al., Thermal boundary resistance measurement and analysis across SiC/SiO2 interface. 2019. 115(10): p. 101603.
73. Casady, J., et al. 900 V DMOS and 1100 V UMOS 4H-SiC power FETs. in 1997 55th Annual Device Research Conference Digest. 1997. IEEE.
77
74. Atlas, D.S.J.S.I.S., Santa Clara, CA, USA, Atlas user’s manual. 2005.
75. Ayalew, T., SiC semiconductor devices technology, modeling and simulation. 2004: na.
76. Sochacki, M., et al., Interface traps in Al/HfO2/SiO2/4H-SiC metal-insulator-semiconductor (MIS) structures studied by the thermally-stimulated current (TSC) technique. 2016. 157: p. 46- 51.
77. Gupta, S.K., et al., Capacitance–conductance spectroscopic investigation of interfacial oxide layer in Ni/4H–SiC (0 0 0 1) Schottky diode. 2014. 434: p. 44-50.
78. Thomas, G., Materials science: Invisible circuits. Nature, 1997. 389(6654): p. 907.
79. Lee, H., et al., Moving beyond flexible to stretchable conductive electrodes using metal nanowires and graphenes. Nanoscale, 2016. 8(4): p. 1789-1822.
80. Kim, D.H. and J.A. Rogers, Stretchable electronics: materials strategies and devices. Advanced Materials, 2008. 20(24): p. 4887-4892.
81. Jin, H., et al., Stretchable Dual-Capacitor Multi-Sensor for Touch-Curvature-Pressure-Strain Sensing. Scientific Reports, 2017. 7(1): p. 10854.
82. Wang, J., et al., High-efficiency transfer of percolating nanowire films for stretchable and transparent photodetectors. Nanoscale, 2014. 6(18): p. 10734-10739.
83. Kim, J.S., et al., Control of the electrode work function and active layer morphology via surface modification of indium tin oxide for high efficiency organic photovoltaics. Applied Physics Letters, 2007. 91(11): p. 112111.
84. Kim, H., et al., Electrical, optical, and structural properties of indium–tin–oxide thin films for organic light-emitting devices. Journal of Applied Physics, 1999. 86(11): p. 6451-6461.
85. Lu, N., et al., Failure by simultaneous grain growth, strain localization, and interface debonding in metal films on polymer substrates. Journal of Materials Research, 2009. 24(2): p.
379-385.
86. Cui, J., et al., Indium Tin Oxide Alternatives—High Work Function Transparent Conducting Oxides as Anodes for Organic Light‐Emitting Diodes. Advanced materials, 2001. 13(19): p.
1476-1480.
87. Lee, J.-Y., et al., Solution-processed metal nanowire mesh transparent electrodes. Nano letters, 2008. 8(2): p. 689-692.
88. Gustafsson, G., et al., Flexible light-emitting diodes made from soluble conducting polymers.
Nature, 1992. 357(6378): p. 477.
89. Bae, S., et al., Roll-to-roll production of 30-inch graphene films for transparent electrodes.
Nature nanotechnology, 2010. 5(8): p. 574.
90. Jeon, Y., et al., Highly flexible touch screen panel fabricated with silver nanowire crossing electrodes and transparent bridges. Journal of the Optical Society of Korea, 2015. 19(5): p.
508-513.
78
91. Madaria, A.R., A. Kumar, and C. Zhou, Large scale, highly conductive and patterned transparent films of silver nanowires on arbitrary substrates and their application in touch screens. Nanotechnology, 2011. 22(24): p. 245201.
92. Van De Groep, J., P. Spinelli, and A. Polman, Transparent conducting silver nanowire networks.
Nano letters, 2012. 12(6): p. 3138-3144.
93. Mutiso, R.M., et al., Integrating simulations and experiments to predict sheet resistance and optical transmittance in nanowire films for transparent conductors. 2013. 7(9): p. 7654-7663.
94. Lee, S., et al., Ag nanowire reinforced highly stretchable conductive fibers for wearable electronics. Advanced Functional Materials, 2015. 25(21): p. 3114-3121.
95. Karki, K., et al., Lithium-assisted electrochemical welding in silicon nanowire battery electrodes. Nano letters, 2012. 12(3): p. 1392-1397.
96. Choi, D.Y., et al., Annealing-free, flexible silver nanowire–polymer composite electrodes via a continuous two-step spray-coating method. Nanoscale, 2013. 5(3): p. 977-983.
97. Song, T.-B., et al., Nanoscale joule heating and electromigration enhanced ripening of silver nanowire contacts. ACS nano, 2014. 8(3): p. 2804-2811.
98. Wei, B., et al., A highly conductive and smooth AgNW/PEDOT: PSS film treated by hot-pressing as electrode for organic light emitting diode. Organic Electronics, 2017. 43: p. 182-188.
99. Garnett, E.C., et al., Self-limited plasmonic welding of silver nanowire junctions. Nature materials, 2012. 11(3): p. 241-249.
100. Chung, W.-H., S.-H. Kim, and H.-S. Kim, Welding of silver nanowire networks via flash white light and UV-C irradiation for highly conductive and reliable transparent electrodes. Scientific reports, 2016. 6.
101. Schuller, J.A., et al., Plasmonics for extreme light concentration and manipulation. Nature materials, 2010. 9(3): p. 193.
102. Holz, C. and P. Baudisch. Fiberio: a touchscreen that senses fingerprints. in Proceedings of the 26th annual ACM symposium on User interface software and technology. 2013. ACM.
103. Harrison, C., M. Sato, and I. Poupyrev. Capacitive fingerprinting: exploring user differentiation by sensing electrical properties of the human body. in Proceedings of the 25th annual ACM symposium on User interface software and technology. 2012. ACM.
104. Ma, H., et al., On-display transparent half-diamond pattern capacitive fingerprint sensor compatible with AMOLED display. IEEE Sensors Journal, 2016. 16(22): p. 8124-8131.
105. Huang, T.-H., et al., A device for skin moisture and environment humidity detection. Sensors and Actuators B: Chemical, 2008. 134(1): p. 206-212.
106. Sekiguchi, N., et al., Microsensor for the measurement of water content in the human skin.
Sensors and Actuators B: Chemical, 2001. 78(1-3): p. 326-330.
107. Javid, B., F. Fotouhi-Ghazvini, and F.S. Zakeri, Noninvasive optical diagnostic techniques for
79
mobile blood glucose and bilirubin monitoring. Journal of medical signals and sensors, 2018.
8(3): p. 125.
108. Shaltis, P.A., A. Reisner, and H.H. Asada. Wearable, cuff-less PPG-based blood pressure monitor with novel height sensor. in 2006 International Conference of the IEEE Engineering in Medicine and Biology Society. 2006. IEEE.
109. Fukushima, H., et al. Estimating heart rate using wrist-type photoplethysmography and acceleration sensor while running. in Engineering in Medicine and Biology Society (EMBC), 2012 Annual International Conference of the IEEE. 2012. IEEE.
110. Guzik, P. and M. Malik, ECG by mobile technologies. Journal of electrocardiology, 2016. 49(6):
p. 894-901.
111. Halcox, J.P., et al., Assessment of remote heart rhythm sampling using the AliveCor heart monitor to screen for atrial fibrillation: the REHEARSE-AF study. Circulation, 2017. 136(19):
p. 1784-1794.
112. Nemati, S., et al. Monitoring and detecting atrial fibrillation using wearable technology. in Engineering in Medicine and Biology Society (EMBC), 2016 IEEE 38th Annual International Conference of the. 2016. IEEE.
113. Oresko, J.J., et al., A wearable smartphone-based platform for real-time cardiovascular disease detection via electrocardiogram processing. IEEE Transactions on Information Technology in Biomedicine, 2010. 14(3): p. 734-740.
114. Kim, H.-K., S. Lee, and K.-S. Yun, Capacitive tactile sensor array for touch screen application.
Sensors and Actuators A: Physical, 2011. 165(1): p. 2-7.
115. Shirzadfar, H., et al., Heart beat rate monitoring using optical sensors. International Journal of Biosensors & Bioelectronics, 2018. 4(2).
116. Jovanov, E. Vital Sign Monitoring Using Capacitive Sensing. in 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC). 2018. IEEE.
117. Kybartas, D., Capacitive sensor for respiratory monitoring. BIOMEDICAL ENGINEERING 2016, 2016. 19(1).
118. Shelley, K.H., Photoplethysmography: beyond the calculation of arterial oxygen saturation and heart rate. Anesthesia & Analgesia, 2007. 105(6): p. S31-S36.
119. Park, K., et al., A Reconfigurable Readout Integrated Circuit for Heterogeneous Display-based Multi-Sensor Systems. Sensors, 2017. 17(4): p. 759.
120. Luna-Lozano, P.S. and R. Pallàs-Areny. Heart rate detection from impedance plethysmography based on concealed capacitive electrodes. in Proceedings of the XIX IMEKO World Congress.
2009.
121. Kim, S., et al., A highly sensitive capacitive touch sensor integrated on a thin-film-encapsulated active-matrix OLED for ultrathin displays. IEEE Transactions on electron devices, 2011.
80 58(10): p. 3609-3615.
122. Wolf, M., et al., Broadband dielectric spectroscopy on human blood. Biochimica et Biophysica Acta (BBA)-General Subjects, 2011. 1810(8): p. 727-740.
123. González-Sánchez, C., et al., Capacitive sensing for non-invasive breathing and heart monitoring in non-restrained, non-sedated laboratory mice. Sensors, 2016. 16(7): p. 1052.