Photoplethysmograph fingernail sensors for measuring finger forces without haptic obstruction

Mascaro, Stephen A.; Asada, H. Harry

doi:10.1109/70.964669

Cited by 170 publications

(90 citation statements)

References 24 publications

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“…The artificial nail attaches to the back of the fingernail with an adhesive, and wires are routed out for interface with a computer. The PPD sensor response was linear up to 1 N normal force, and beyond 1 N, there was a nonlinear leveling off [14]. The sensor predicted normal force to within 1 N accuracy in the range of 2 N and shear force to within 0.5 N accuracy in the range of 3 N. The relation between sensor response and force differs among subjects and different fingernails for the same subject.…”

mentioning

confidence: 94%

“…The mechanical properties of the fingertip were modeled by Pawluk and Howe [20], [21] with a viscoelastic model with three time constants, whose values were determined to be 0.004, 0.07, and 1.4 s. Over 75% of the magnitude of the response was due to the first two fast terms whose time constants are less than 0.1 s. From pulsatile pressure variation in the data, the blood flow is already restored by the time that the third term dominates. Experimental evidence from Mascaro and Asada [14] verified that the time constant of the response of the blood flow is between 0.1 and 0.4 s, depending on which part of the fingernail is observed.…”

Section: Time Course Of Coloration Effectmentioning

confidence: 99%

“…T HAS BEEN shown that coloration changes in the fingernail due to fingertip pressure can serve to transduce fingertip force [14], [15]. Pressure at the fingerpad affects blood flow at the fingernail, which causes a nonuniform pattern of color change in the fingernail area.…”

mentioning

confidence: 99%

“…Previously, Mascaro and Asada [14], [15] have proposed a photoplethysmograph (PPD) sensor that has an array of inferred LEDs and photodetectors. It is embedded in a custom-fabricated artificial nail made of epoxy.…”

mentioning

confidence: 99%

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Predicting Fingertip Forces by Imaging Coloration Changes in the Fingernail and Surrounding Skin

Sun

Hollerbach

Mascaro

2008

IEEE Trans. Biomed. Eng.

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Abstract-This paper presents an external camera method for measuring fingertip forces by imaging the fingernail and surrounding skin. A 3-D model of the fingernail surface and skin is obtained with a stereo camera and laser striping system. Subsequent images from a single camera are registered to the 3-D model by adding fiducial markings to the fingernail. Calibration results with a force sensor show that the measurement range depends on the region of the fingernail and skin. A generalized least squares model is developed to predict fingertip force given coloration changes, and results for normal and shear force measurement are presented.

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mentioning

confidence: 94%

Section: Time Course Of Coloration Effectmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Predicting Fingertip Forces by Imaging Coloration Changes in the Fingernail and Surrounding Skin

Sun

Hollerbach

Mascaro

2008

IEEE Trans. Biomed. Eng.

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“…Nowadays, force sensing becomes an important component for diver applications in biomedical applications and orthopedic rehabilitation. Thus, tactile sensors have been used in hand clinical evaluations and foot rehabilitation ; (Mascaro & Asada, 2001); (Boukhenous & Attari, 2007); (Attari & Boukhenous, 2008). Human tactile sensing is achieved by means of at least four different types of receptor cells (Jayawant, 1989); (Cowie et al, 2007) and is used to feel, grasp and manipulate objects, and to assess attributes such as shape, size, texture, temperature, hardness, discontinuities such as holes or edges, and movement, including vibration.…”

Section: Introductionmentioning

confidence: 99%

A Low Cost Instrumentation Based Sensor Array for Ankle Rehabilitation

Boukhenous¹,

Attari²

2011

Biomedical Engineering, Trends in Electronics, Communications and Software

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Elastomeric Electronic Skin for Prosthetic Tactile Sensation

Gerratt

Michaud

Lacour

2015

Adv Funct Materials

344

258

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Human skin is capable of transducing pressures in the range of 100 Pa (light touch) to 1 MPa (full body weight bearing); common tasks such as object manipulation develop contact pressures on the order of 10 kPa. [ 21,22 ] Moreover, sensitivity of human skin to applied pressures is complex and varies widely by type of mechanoreceptor and type of stimulation (normal pressure, shear pressure, frequency, magnitude). [ 23 ] Although distributed sensing using arrays of thin-fi lm transistors on ultrathin plastic foils combined with soft mechanical sensors has also been demonstrated, [ 11,[24][25][26] most reported skin-like sensors are discrete elements. An unmet demand for truly wearable e-skin is mechanical compliance. Natural skin is soft and elastic. Electronic skins should therefore wrap over the external surface of the body and accompany movement, in particular over joints and articulations. To date, pressure sensing data gloves and tactile skins are mainly prepared with fl exible polymers [27][28][29] and conductive textiles. [ 30,31 ] These constructs conform well to developable surfaces (e.g., the arm and fi nger phalanges) but wrinkle and often fail when placed over articulations (e.g., the elbow and fi nger joints). [ 32 ] E-skins prepared entirely with stretchable materials appear as a necessary starting point. Over the last decade, multiple designs of stretchable tactile sensors using elastomers, thin fi lms, composites, [ 19,33 ] and conductive liquids [34][35][36] have been reported, but their systematic characterization in real-life conditions is often incomplete. Stretchable strain sensors are often demonstrated in complex real-life scenarios, [ 37,38 ] but in the literature related to stretchable tactile sensors, demonstrations involving dynamic states where bending and stretching of the sensors occur simultaneously are not common, likely due to the challenges of removing cross-sensitivities to strain and noise received from the body. [ 19,20,39 ] In this paper, we report on a stretchable e-skin designed to be worn over the hand, monitor live fi nger movement, and register distributed pressure along the entire length of the fi nger. The sensory skin is thin and made entirely of elastic materials, thereby can be mounted on a glove and worn without impeding hand movement ( Figure 1 ). The read-out electronics are integrated in a small printed circuit board (PCB) located immediately at the base of each fi nger. Capacitive pressure sensors combine stretchable gold thin-fi lm electrodes with porous silicone foam (Figure 1 a) and display high sensitivity across much of the large dynamic pressure range of human skin. Six adjacent pressure sensors cover the entire length of the fi nger; two soft metallic shielding layers eliminate noise and cross-sensitivity over the skin and enable multi-touch with This report demonstrates a wearable elastomer-based electronic skin including resistive sensors for monitoring fi nger articulation and capacitive tactile pressure sensors that register distributed pressure along ...

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Photoplethysmograph fingernail sensors for measuring finger forces without haptic obstruction

Cited by 170 publications

References 24 publications

Predicting Fingertip Forces by Imaging Coloration Changes in the Fingernail and Surrounding Skin

Predicting Fingertip Forces by Imaging Coloration Changes in the Fingernail and Surrounding Skin

A Low Cost Instrumentation Based Sensor Array for Ankle Rehabilitation

Elastomeric Electronic Skin for Prosthetic Tactile Sensation

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