Hair comb attachment for fnirs probes to improve SNR and subject inclusivity

Abstract

A hair manipulation mechanism for use with an optrode of a functional near-infrared spectroscopy (fNIRS) system. The hair manipulation mechanism including a body defining a central axis, and a plurality of comb elements. Where each comb element includes at least one leg extending therefrom that is configured to engage the one or more hairs of the entity, and where each comb element of the plurality of comb elements is adjustable between a first position, in which the comb element is spaced a first radial distance from the central axis, and a second, position, in which the comb element is spaced a second radial distance from the central axis greater than the first distance.

Description

Attorney Docket No. 093386-0044-WO01 HAIR COMB ATTACHMENT FOR FNIRS PROBES TO IMPROVE SNR AND SUBJECT INCLUSIVITY STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0001] This invention was made with government support under AG072188 awarded by the National Institutes of Health. The government has certain rights in the invention. CROSS-REFERENCE TO RELTAED APPLICATIONS

[0001] This application claims priority to prior-filed, co-pending U.S. Provisional Patent Application No.63 / 625,551 filed on January 26, 2024. The entire contents of which are incorporated herein by reference. BACKGROUND

[0002] Functional near-infrared spectroscopy (fNIRS) systems are being utilized for neuromonitoring at an increased rate over the past decade due to its noninvasive nature, high level of portability and lightweight systems. fNIRS systems function by measuring changes in the relative concentrations of oxy- and deoxy-hemoglobin by emitting light in the near-infrared range and detecting the backscattered signal. Through this process, fNIRS technology generates estimates of cerebral metabolic activity and has been used to map cortical activity from multiple brain regions concurrently. To receive high quality data and generate accurate representations of brain activity, the sources that emit light and detectors that receive the backscattered signal must be in proper contact with the patient’s scalp.

[0003] Human hair is a known factor that can prevent proper coupling of the scalp to system sources and detectors, which are also known as optodes, because hair strands are known to scatter light in the near-infrared range. Scattering of the input or backscattered optical signal results in signal loss and a reduction in signal-to-noise ratio (SNR). Previous studies have shownthat dark hair colors contribute more to poor scalp-to-optode coupling and lower SNR however,increased hair density across multiple hair colors is also known to contribute to lower SNR.Attorney Docket No. 093386-0044-WO01

[0004] Issues with hair obstruction have driven fNIRS researchers to probe scalp regions and patient populations that make proper scalp-to-optode coupling easier to achieve. Currently, many fNIRS studies focus on data collection in the prefrontal and anterior temporal regions of the brain. Additionally, fNIRS is commonly applied to infant populations whose hair density is decreased in comparison to matured populations. The need to study brain regions in addition to the prefrontal and temporal regions and to collect data from a variety of older, broader subject populations has also become more significant as fNIRS continues to be utilized in neuroimaging studies and leveraged for clinical usage.

[0005] Commercial vendors of fNIRS technology currently promote through-hair usage of their devices through two main approaches. The first approach is to place the system on the user’s head and shake the device back and forth. In this approach, the system optodes are already positioned into a cap system that covers the head, and the shaking promotes the movement of the probes through the hair and down to the surface of the scalp. The problem with this approach is that it does not consistently achieve hair separation and proper scalp-to-optode coupling across all optodes. Commercial cap systems are non-rigid, and the shaking of the cap promotes hair separation to various degrees based on factors such as where the cap is gripped during shaking, which regions of the cap are shaken most, and how heterogenous the hair distribution is under the cap (i.e., differences in hair style and thickness).

[0006] The second approach promoted by commercial vendors is the use of an external, hair- clearing tool to separate hair. In this approach, the cap system is, first, placed on the user’s head without the probes attached, leaving an opening where hair can be accessed. Secondly, the outside tool is used to manually separate hair strands and create clearance before the probes are finally attached to the system. A wooden or plastic stick-like tool is commonly used. The main disadvantage of this approach is the time required to achieve hair separation. Using an external tool to manually clear hair strands one opening at a time is a time-consuming task for researchers. Diligently clearing hair strands from one opening using an external tool can take 30 seconds to one minute in duration. The time needed to clear hair increases as the number of probes in the system increases, and in the interest of whole-cortex imaging, it is not uncommon to have upwards of 60 probes that need to be cleared.Attorney Docket No. 093386-0044-WO01

[0007] Commercial vendors have started implementing designs with motivated features to achieve proper scalp-to-optode coupling. For example, the LUMO system by Gowerlabs and Flow system by Kernel are beginning to incorporate light guides, or overlays that help to comb hair out of the way of optodes. While light guides are promising for hair clearance, these designs are only designed for and included in the systems mentioned previously. This lack of access to light guides for researchers would require them to purchase systems that reach $100k in cost. Further, even if the light guides could be purchased separately from entire systems, they are outfitted for specific optode designs and could not be easily integrated into other systems. An approach developed by Khan et al. employs a “brush optode” design, which leverages fiber optic bundles attached to the ends of light source or detector probes to navigate through hair and contact the scalp. While the brush optode design was shown to reduce the setup time and improve the SNR of the system, a simpler mechanical design can further improve on the timing and SNR results.

[0008] Accordingly, for fNIRS technology to see continued increase in usage and broader applicability both in brain regions and patient populations, it would be desirable to develop a device or system that reduces the time to clear hair to enable improved scalp-optode coupling through hair in fNIRS systems. SUMMARY

[0003] The present disclosure provides a mechanical attachment that can be connected to system optodes to improve scalp-optode coupling through hair in fNIRS systems. In some embodiments, the attachment comprises a flexible material that enables conformity and subject comfort, comb-like features that can separate hair strands, is operable through a simple twisting mechanism, and can be incorporated into current, commercial cap systems. In general, the attachment includes three features: leg pieces or comb elements that act as comb teeth to move hair out of the way, a top that is twistable and controls the leg pieces, and a bottom that holds the leg pieces in place.

[0004] In some aspects, there are a total of six leg pieces that work in tandem separate hair so the system optodes can make proper contact. Each leg piece is approximately a rectangle measuring 4mm x 6mm x 3 mm in dimension. Each leg piece has comb-like extrusions to aid inAttorney Docket No. 093386-0044-WO01 separating the hair. Each leg piece also has an extruded cylinder, measuring about 2mm in diameter, on the top layer that interacts with the twistable top piece, which controls whether the leg pieces are stationary (and the system is closed) or mobile (and the system is expanded and separating hair). The top piece has two components that serve two purposes. The bottom component interacts with the leg pieces and aids in separating hair through. The circular openings in the bottom component interact with the extruded cylinder on the leg pieces, and when the top piece is twisted, the circular pattern converts the rotational movement into a linear movement in the leg pieces that allows for hair clearance. The bottom component measures about 24mm in diameter and about 2mm in thickness. The top component interacts with fNIRS system optodes. The top component was designed as a cylindrical disk with an inner diameter of about 10mm to support probe placement, and the disk narrows in outer diameter from about 12mm to about 11mm to support placement in the cap system. The bottom piece serves to keep the system connected and in place. The bottom piece has a separator that acts to keep the leg pieces at a fixed distance apart from each other and to facilitate in guiding the leg pieces in a linear pathway away from the center of the design. The bottom piece also contains arm-like pieces that connect it to the twistable top and keep the whole system connected, which simplifies deployment for researchers. The bottom piece measures about 24mm in diameter and has a maximum height of about 2 mm.

[0005] In some aspects, the attachment is the first of its type to have all components be totally 3D-printable, which increases its availability and likelihood to be used by researchers.

[0006] In some aspects, the attachment’s twistable operating technique is novel to fNIRS attachments and promotes simple / timely usability for researchers.

[0007] In some aspects, the array of comb-feature designs in the attachment is intended to promote inclusivity in subject populations.

[0008] In some aspects, the attachment is intended to be compatible with multiple commercial systems, which also promotes availability / usability among researchers.Attorney Docket No. 093386-0044-WO01

[0009] In one aspect, a hair manipulation mechanism for manipulating one or more hairs on an entity, the hair manipulation mechanism including a body defining a central axis, a plurality of comb elements, where each comb element includes at least one leg extending therefrom that is configured to engage the one or more hairs of the entity, and where each comb element of the plurality of comb elements is adjustable between a first position, in which the comb element is spaced a first radial distance from the central axis, and a second position, in which the comb element is spaced a second radial distance from the central axis greater than the first distance.

[0010] Alternatively or additionally, where the hair manipulation mechanism is operable in a first configuration, in which each comb element of the plurality of comb elements is in its corresponding first position, and a second configuration, in which each comb element of the plurality of comb elements is in its corresponding second position.

[0011] Alternatively or additionally, where the body includes a first portion and a second portion movable with respect to the first portion, and wherein moving the first portion relative to the second portion is configured to cause the hair manipulation mechanism to change between the first and second configurations.

[0012] Alternatively or additionally, where the first portion is rotatable with respect to the second portion about the central axis.

[0013] Alternatively or additionally, where the first radial distance is the same for each comb element of the plurality of comb elements.

[0014] Alternatively or additionally, where the second radial distance is the same for each comb element of the plurality of comb elements.

[0015] Alternatively or additionally, where the leg extending from at least one comb element extends in an axial direction.

[0016] Alternatively or additionally, where the leg extending from at least one comb element extends radially outwardly.

[0017] Alternatively or additionally, where the body includes a first portion and a second portion rotatable with respect to the first portion about the central axis, and wherein rotating theAttorney Docket No. 093386-0044-WO01 first portion relative to the second portion is configured to cause at least a portion of the plurality of comb elements to move between their respective first and second positions.

[0018] Alternatively or additionally, where the body defines a channel extending therethrough, and wherein the channel is co-axially aligned with the central axis.

[0019] Alternatively or additionally, where the channel is configured for an fNIRS optode to be coupled thereto.

[0020] Alternatively or additionally, where the plurality of comb elements are spaced equally over 360 degrees about the central axis of the body.

[0021] In another aspect, a hair manipulation mechanism for attachment to an optode, the hair manipulation mechanism including a body defining a central axis, where the body includes a first portion and a second portion movable with respect to the first portion, a plurality of comb elements, where each comb element includes a tooth extending therefrom, and where moving the first portion with respect to the second portion is configured to cause each comb element to move radially with respect to the central axis.

[0022] Alternatively or additionally, where the first portion is rotatable with respect to the second portion about the first axis, and where rotating the first portion in a first direction relative to the second portion is configured to cause each comb element to move radially outwardly away from the central axis.

[0023] Alternatively or additionally, where rotating the first portion in a second direction opposite to the first direction relative to the second portion is configured to cause each comb element to move radially inwardly toward the central axis.

[0024] Alternatively or additionally, where the first portion of the body defines a plurality of spiral grooves, and where each comb element of the plurality of comb elements includes a protrusion at least partially positioned within a corresponding spiral groove.

[0025] Alternatively or additionally, where when the first portion of the body is stationary relative to the second portion each of the comb elements are radially fixed relative to the central axis.Attorney Docket No. 093386-0044-WO01

[0026] Alternatively or additionally, where the body defines a channel extending therethrough, where the channel is co-axial with the central axis, and where each comb elements is movable radially between a first position wherein at least a portion of the comb element is positioned within the channel, and a second position, in which the comb element is not positioned within the channel.

[0027] In another aspect, a hair manipulation mechanism for attachment to an optode, the hair manipulation mechanism including a body defining a channel extending therethrough, a first comb element movable with respect to the body, where the first comb element includes a tooth extending therefrom, a second comb element movable with respect to the body, where the second comb element includes a tooth extending therefrom, and where the hair manipulation mechanism is adjustable between a first configuration, in which the first and second comb elements are at least partially positioned within the channel, and a second configuration, in which the first and second comb elements are not positioned within the channel.

[0028] Alternatively or additionally, where the first comb element is spaced a first distance from the second comb element in the first configuration, and wherein the first comb element is spaced a second distance greater than the first distance from the second comb element in the second configuration.

[0029] Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG.1A is a side view of the hair manipulation mechanism of the current application with comb elements in a first position and an optode coupled thereto.

[0031] FIG.1B is a side view of the hair manipulation mechanism of FIG.1B with the comb elements in a second position.

[0032] FIG.2 is an exploded view of the hair manipulation mechanism of FIG.1A.

[0033] FIG.3A is a top view of the second segment of the body of the hair manipulation mechanism of FIG.1A.Attorney Docket No. 093386-0044-WO01

[0034] FIG.3B is a bottom view of the second segment of the body of the hair manipulation mechanism of FIG.1A.

[0035] FIG.4A is a top view of the first segment of the body of the hair manipulation mechanism of FIG.1A.

[0036] FIG.4B is a bottom view of the first segment of the body of the hair manipulation mechanism of FIG.1A.

[0037] FIG.5A is a top view of the plurality of comb elements of the hair manipulation mechanism of FIG.1A.

[0038] FIG.5B is a bottom view of the plurality of comb elements of the hair manipulation mechanism of FIG.1A.

[0039] FIG.6 illustrates the hair manipulation mechanism of FIG. 1A fitted to a patient’s scalp.

[0040] FIGS.7A-7H illustrate various embodiments of the comb elements of the hair manipulation mechanism of FIG.1A.

[0041] FIG.7J is a detailed side view of a tooth extending from a comb element of the hair manipulation mechanism of FIG.1A.

[0042] FIGS.8-17 include experimentation results regarding the operation of the hair manipulation mechanism of FIG.1A. DETAILED DESCRIPTION

[0043] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.Attorney Docket No. 093386-0044-WO01

[0044] FIGS.1A-2 illustrate a hair manipulation mechanism 100 for attachment to an optode 104 to improve scalp-optode coupling through hair in functional near-infrared spectroscopy (fNIRS) systems 108. More specifically, the hair manipulation mechanism 100 is configured to be attached to an optode 104 whereby a plurality of comb or brush elements 112 incorporated into the mechanism 100 quickly separate or otherwise displace hair strands away from the sensing zone 116 of the attached optode 104. As a result, the hair manipulation mechanism 100 is able to decrease the amount of time it takes to clear a patient or other entities’ hair from a given sensing zone 116 while maintaining or even increasing the signal-to-noise ratios (SNRs) of the resulting readings.

[0045] Generally speaking, fNIRS systems 108 include a plurality of optodes 104 coupled to a central processor 124 via a cable 128 and the like. Each optode 104, in turn, is configured to collect data from a given sensing zone 116 (e.g., the area on the patient’s tissue where data is being collected). As shown in FIGS. 1A and 1B, each optode 104 includes an elongated body 120 with a sensing tip 132 on one end thereof configured to physically engage the patient’s tissue within the sensing zone 116 and extract data therefrom. In some embodiments, the optode 104 also defines a sensing axis 136 generally oriented normal to the sensing tip 132.

[0046] As shown in FIG.2, the hair manipulation mechanism 100 includes a body 140 defining a central axis 156, and a plurality of brush or comb elements 112 movable relative to the body 140. Specifically, each comb element 112 is movable relative to the body 140 between a first position (see FIG.1A), in which the comb element 112 is a first distance from the central axis 156, and a second position (see FIG. 1B), in which the comb element 112 is a second distance from the central axis 156 greater than the first distance. The hair manipulation mechanism 100 also includes a drive mechanism 144 to coordinate the movement of the individual comb elements 112 relative to the body 140.

[0047] In other embodiments, the mechanism 100 may be configured such that at least two of the plurality of comb elements 112 are positioned across or opposite each other, such that the resulting pair moves between a first position, in which the pair of comb elements 112 are spaced a first distance from each other (FIG.1A), and a second position, in which the pair of combAttorney Docket No. 093386-0044-WO01 elements 112 are spaced a second distance from each other (FIG.2A) greater than the first distance.

[0048] The body 140 of the hair manipulation mechanism 100 is substantially cylindrical in shape having a first or sensing end 148, and a second end 152 opposite the first end 148. The body 140 defines a probe channel 160 configured to at least partially receive the optode 104 therein, and a plurality of passages 164 each sized to receive a corresponding comb element 112 therein. While the illustrated hair manipulation mechanism 100 is shown being attached to an optode 104, it is understood that in other embodiments different types of probes and / or sensors may be attached to the mechanism 100 for use together therewith. In the illustrated embodiment, the body 140 is formed from polylactic acid (PLA) as it can be easily cleaned and disinfected while being durable enough to be used repeatedly. PLA can also be formed quickly using 3D printing techniques. However, in other embodiments, different manufacturing techniques like machining, molding, casting, and the like may be used for one or more elements of the mechanism 100.

[0049] The probe channel 160 of the body 140 is sized and shaped so that a probe (e.g., an optode 104) can be fixedly coupled thereto. In some embodiments, the channel 160 is configured so that an optode 104 is at least partially positioned within the channel 160 so that the sensing axis 136 of the optode 104 is parallel to the central axis 156 of the body 140. In other embodiments, the channel 160 is configured so that the optode 104 is at least partially positioned within the channel 160 so that the sensing tip 132 of the optode 104 is positioned proximate and / or facing out of the first end 148 of the channel 160. In such embodiments, the sensing tip 132 of the optode 104 may even extend beyond the second end 148 of the channel 160 to physically engage the patient’s scalp directly. In still other embodiments, the optode 104 is at least partially positioned within the channel 160 so that the sensing axis 136 co-axial with the central axis 156 (see Fig 1A). As shown in FIG. 1A, the illustrated channel 160 extends completely through the body 140 (e.g., through both the first segment 168 and the second segment 172) being open on both the first end 148 and the second end 152 thereof. The illustrated channel 160 is also co-axial with the central axis 156.Attorney Docket No. 093386-0044-WO01

[0050] While the illustrated channel 160 is substantially cylindrical in shape, it is understood that in other embodiments different cross-sectional shapes may be used to accommodate different types of optodes. For example, the optodes may be, but are not limited to, triangular, hexagonal, polygonal, oval, elliptical the like.

[0051] As shown in FIG.2, the plurality of passages 164 of the body 140 are each sized and shaped to at least partially support a corresponding one of the comb elements 112 therein. More specifically, each passage 164 is sized to allow a corresponding comb element 112 to slide axially along a corresponding passage axis 162 but restrict any lateral or rotational movement therein. In some embodiments, each passage 164 is oriented perpendicular to the central axis 156 (e.g., the passage axis 162 is perpendicular to the central axis 156) being open to the probe channel 160 on one end and open to the exterior of the body 140 on the opposite end. In still other embodiments, the plurality of passages 164 are equally positioned circumferentially about the central axis 156 over 360 degrees. Specifically, the illustrated body 140 includes six passages 164 each positioned approximately 60 degrees apart (±0.25%, ±0.5%, ±1%, ±2%, ±5%, ±10%) about the central axis 156. While the illustrated body 140 has six passages 164 to accommodate six comb elements 112, it is understood that in other embodiments more or fewer comb elements 112 may be present. In still other embodiments, the passages 164 may include one or more pairs of passages 164 spaced approximately 180 degrees apart (±0.5 degrees, ±1 degree, ±2 degrees,±3 degrees, ±5 degrees, ±10 degrees e.g., opposite each other) to produce a separating motion asthe pair of comb elements 112 positioned therein are moved apart during use.

[0052] In the illustrated embodiment, the body 140 has a first or bottom segment 168 forming the first end 148, and a second or top segment 172 movable with respect to the first segments 168 and forming the second end 152. In some embodiments, the first and second segments 168, 172 form a generally stepped cylindrical shape.

[0053] The bottom segment 168 of the body 140 includes a base plate 176 and a plurality of protrusions 180 extending axially from the base plate 176 to at least partially define the passages 164 therebetween. In the illustrated embodiment, the protrusions 180 are substantially triangular in cross-sectional shape such that the passages 164 formed therebetween have a constant widthalong their radial length (e.g., along each passage axis 162 see FIG. 4A). However, in otherAttorney Docket No. 093386-0044-WO01 embodiments, different sizes and shapes of protrusions 180 may be present to produce different cross-sectional shapes of passages 164. The illustrated passages 164 have a radial length of approximately 11.8 mm (±0.25%, ±0.5%, ±1%, ±2%, ±5%, ±10%). Accordingly, the base plate 176 of the illustrated embodiment has an exterior diameter of approximately 24 mm (±0.25%, ±0.5%, ±1%, ±2%, ±5%, ±10%). As the illustrated body 140 includes six passages 164 spaced equally about 360 degrees, the tip of the protrusions form a 60 degree angle (±0.25%, ±0.5%, ±1%, ±2%, ±5%, ±10%).

[0054] The base plate 176 also defines an opening 184 that forms a portion of the probe channel 160. In some embodiments, the opening 184 is sized so that it extends radially beyond the protrusions 180 (e.g., a portion of the opening 184 is positioned radially outwardly of theradially inward-most point of the protrusions 180 see FIG. 4A). The increased size of theopening 184 allows for the comb elements 112 to have a larger range of travel during use.

[0055] The first segment 168 also includes one or more clips 190 for securing the first segment 168 to the second segment 172. In the illustrated embodiment, the clips 190 are generally “L-shaped” and configured so that the second segment 172 is axially restrained relative to the first segment 168 but allowed to rotate about the central axis 156 with respect thereto. In other embodiments, different types of connections may be used to allow the two segments 168, 172 to move with respect to one another. In other embodiments, the clips 190 may also be configured so that the second segment 172 may be detached from the first segment 168. The detachment may be used to allow the individual comb elements 112 to be removed or replaced (e.g., to adopt different teeth layouts, discussed below) or to allow the device 100 to be more easily cleaned or stored.

[0056] As shown in FIGS.2, 3A, and 3B, the second segment 172 of the hair manipulator 100 includes a drive disk 200 oriented normal to the central axis 156 and a projection 204 extending axially from the drive disk 200 to produce the second end 152 of the body 140. In the illustrated embodiment, the projection 204 is substantially annular in shape such that the interior thereof forms a portion of the probe channel 160 while the exterior includes a locking groove 208 serving as an attachment point to secure the optode 104 to the hair manipulator 100 duringAttorney Docket No. 093386-0044-WO01 use. As discussed above, the channel 160 may have a cross-sectional shape configured to accommodate a plurality of different types of optodes 104.

[0057] While the illustrated channel 160 has a substantially circular cross-sectional shape, it is understood that in other embodiments, different cross-sectional shapes may be used as needed to accommodate the exterior size and shape of the optode 104 being attached thereto. Furthermore, the locking groove 208 may include other features and / or elements needed to fixedly secure the elongated body 120 of the optode 104 to the body 140 of the manipulator 100. In the illustrated embodiment, the interior diameter of the probe channel 160 formed by the projection 204 is approximately 10.3 mm (±0.25%, ±0.5%, ±1%, ±2%, ±5%, ±10%). The illustrated disk 200 also has an outer diameter of approximately 24 mm (±0.25%, ±0.5%, ±1%, ±2%, ±5%, ±10%).

[0058] The drive disk 200 of the second segment 172 includes a plurality of cam slots 212 formed therein with each slot 212 corresponding with a given comb element 112. During use, the drive disk 200 and associated slots 212 serve as the drive mechanism 144 for the hair manipulator 100 such that the relative size, shape, and position of the slots 212 help control and coordinate the movement of the comb elements 112 within their corresponding passages 164.

[0059] As shown in FIGS.2 and 3A, each slot 212 of the drive disk 200 is sized and shaped to receive at least a portion of a pin 216 from a given comb element 112 (discussed below) therein such that movement of the pin 216 within the slot 212 causes the comb element 112 to move relative to the body 140 (e.g., along the passage axis 162). In some embodiments, each cam slot 212 is spiral shaped such that it extends radially outwardly away from the central axis 156 as it travels in a counter-clockwise direction (see FIG.3A). Accordingly, rotating the second segment 172 in a clockwise direction relative to the first segment 168 (see FIG.3A) causes each comb element 112 to travel in a radially outward direction away from the central axis 156 (e.g., from its first position toward its second position along the passage axis 162). In contrast, rotating the second segment 172 in a counter-clockwise direction relative to the first segment 168 (see FIG.3A) causes each comb element 112 to travel in a radially inward direction toward the central axis 156 (e.g., from its second position toward its first position along the passage axis 162). The slots 212 are also sized so that when the second segment 172 is stationary relative toAttorney Docket No. 093386-0044-WO01 the first segment 168 each of the comb elements 112 are fixed in place. Specifically, the comb elements 112 are fixed so that they will not move relative toward or away from the central axis 156 even if acted upon by an external force. In some embodiments, the slots 212 have a generally equal width along their spiraled length that substantially corresponds to the diameter of the pin 216. In the illustrated embodiment, the width of each slot 212 is approximately 1.5 mm (±0.25%, ±0.5%, ±1%, ±2%, ±5%, ±10%).

[0060] While the slots 212 of the illustrated drive disk 200 are sized, shaped, and positioned so that each comb element 112 moves between its respective first position and second positions together as a unit, it is understood that in other embodiments different movement profiles may be used. For example, in some embodiments the drive disk 200 may be configured so that sub- groups of the comb elements 112 may move between different positions and / or move at different times. Furthermore, while the drive disk 200 utilizes rotational motion to actuate the comb elements 112 during operation, it is understood that in other embodiments the slots 212 may be shaped to accommodate relative translational motion, pivoting motion, and the like between the two segments 168, 172.

[0061] Furthermore, while the slots 212 of the illustrated drive disk 200 are sized, shaped, and positioned such that each comb element 112 is spaced the same first distance from the axis 156 when in the first position and is spaced the same second distance from the axis 156 when in the second position, it is understood that in other embodiments the slots 212 may be configured so that various comb elements 112 are positioned at different distances from the axis 156 while in the first position, the second position, or both. The slots 212 may also be configured so that the speed at which the comb elements 112 move along the passage axis 162 can be the same throughout or different.

[0062] As shown in FIGS.7A-7H, each comb element 112 of the hair manipulator 100 includes an elongated body having a first end 220 and a second end 224 opposite the first end 220. In the illustrated embodiment, the first end 220 is tapered to provide additional clearance for adjacent comb elements 112 when the elements 112 are positioned proximate the central axis156 (e.g., at or near the first position see FIGS. 5A and 5B). More specifically, the first end 220is tapered to produce a 60-degree point. The comb element 112, in turn, has a cross-sectionalAttorney Docket No. 093386-0044-WO01 shape that generally corresponds to the cross-sectional size and shape of the passage 164 in which it is positioned. In the illustrated embodiment, the element 112 has a rectangular cross- sectional shape that is approximately 4 mm tall (±0.25%, ±0.5%, ±1%, ±2%, ±5%, ±10%) by approximately 4 mm wide (±0.25%, ±0.5%, ±1%, ±2%, ±5%, ±10%).

[0063] Each comb element 112 also includes a pin 216. As shown in FIG.2, the pin 216 is sized and positioned such that it is at least partially received within a corresponding slot 212 of the drive disk 200. During use, rotation of the second segment 172 relative to the first segment 168 causes the pin 216 to travel along said slot 212 whereby any instances where the slot 212 moves radially away from the central axis 156 causes the comb element 112 to also move away from the central axis 156 (e.g., move axially along the passage axis 162 away from the central axis 156) and any instances where the slot 212 moves radially toward the central axis 156 causes the comb element 112 to also move toward the central axis 156 (e.g., move axially along the passage axis 162 toward the central axis 156). In the illustrated embodiment, the pin 216 is approximately 5 mm long (±0.25%, ±0.5%, ±1%, ±2%, ±5%, ±10%) and 1.25 mm in diameter (±0.25%, ±0.5%, ±1%, ±2%, ±5%, ±10%).

[0064] Each comb element 112 also includes one or more legs or teeth 228 extending therefrom to form a comb feature 230 configured to engage and move hairs in the direction of travel of the comb element 112 (e.g., radially away from the axis 156). More specifically, the teeth 228 extend from the comb element 112 proximate the first end 220 and opposite the pin 216. When assembled, the teeth 228 are configured to extend through the opening 184 of the base plate 176 where they are configured to engage the hairs protruding from the patient’s scalp during use.

[0065] The teeth 228 are formed by coating a first layer or core with an exterior layer of silicone. By doing so, the core or first layer of the tooth 228 provides rigidity while the exterior layer of silicone assures that the resulting tooth 228 is not too sharp so as to damage or scratch the scalp. In the illustrated embodiment, the core of the teeth 228 are coated with a layer of dragon skin FX-pro silicone that is approximately 1 mm thick (±0.25%, ±0.5%, ±1%, ±2%, ±5%, ±10%).Attorney Docket No. 093386-0044-WO01

[0066] As shown in FIGS.7A-7H, the length, thickness, curvature, end shape, stiffness, number, and arrangement of the teeth 228 included in the comb feature 230 of a given comb element 112 may be modified to accommodate different types and styles of hairs typically found on a human scalp. In a first embodiment, three 3.6mm long teeth 228 with a slight curvature and rounded tip may be used to accommodate thick and dense hair as shown in FIG. 7A. In a second embodiment, five 3.6mm long teeth 228 with a slight curvature and rounded tip may be used to accommodate thin and curly hair as shown in FIG.7B. In a third embodiment, three 3.9mm long teeth 228 with a slight curvature and rounded tip may be used to accommodate thin and curly hair as shown in FIG. 7C. In a fourth embodiment, three 3.7mm long teeth 228 with a large curvature and rounded tip may be used to accommodate thin and curly hair as shown in FIG. D. In a fifth embodiment, five 3.6mm long teeth 228 with a large curvature and rounded tip may be used to accommodate thick and curly hair as shown in FIG.7E. In a sixth embodiment, six 3.6mm long teeth 228 with no curvature and with a balled-end may be used to accommodate a high level of curl or coil as shown in FIG.7F. In a seventh embodiment, four 3.6mm long teeth 228 with no curvature and a balled-end may be used to accommodate a high level of curl or coil as shown in FIG.7G. Finally, in an eighth embodiment, one or more 3.0mm long teeth 228 with a non-circular cross-sectional shape may be used to accommodate highly dense hair as shown in FIG.7H. In the eighth embodiment, the teeth 228 may include an elongated “plate-like” construction oriented parallel to the corresponding passage axis 162.

[0067] As shown in FIG.7J, each tooth 228 defines a curvature angle 232. For the purposes of this application the curvature angle 232 is defined as the angle between a first axis aligned with the base 236 of a given tooth 228 and a second axis aligned with the tip 240 of the tooth 228. In some embodiments, a tooth 228 having a small curvature would include teeth 228 with a curvature angle 232 between approximately 170 degrees (±0.25%, ±0.5%, ±1%, ±2%, ±5%, ±10%) and approximately 135 degrees (±0.25%, ±0.5%, ±1%, ±2%, ±5%, ±10%). In contrast, a tooth 228 having a large curvature would include teeth 228 with a curvature angle 232 between 135 degrees (±0.25%, ±0.5%, ±1%, ±2%, ±5%, ±10%) and 90 degrees (±0.25%, ±0.5%, ±1%, ±2%, ±5%, ±10%). In still other embodiments, the teeth 228 of a given comb feature 230 may include teeth 228 having a curvature angle 232 between 155 degrees and 115 degrees. In still other embodiments, the teeth 228 of a given comb feature 230 may include teeth 228 having a curvature angle 232 between 170 degrees and 90 degrees.Attorney Docket No. 093386-0044-WO01

[0068] In constructions where curvature is present, the illustrated teeth 228 curve away from the central axis 156. However, in other embodiments different directions of curvature may be present. In still other embodiments, the teeth 228 may include compound curves extending in different directions.

[0069] To use the hair manipulation mechanism 100, the mechanism 100 is positioned relative to the patient’s scalp (see FIG.6). More specifically, the mechanism 100 is positioned so that the teeth 228 of the comb elements 112 are in physical contact with the hairs of the patient’s scalp and the body 140 is positioned such that the central axis 156 is generally aligned with the desired sensing zone 116 (see FIG.1A). Once in place, the mechanism may be secured in place. To do so, the mechanism 100 may be incorporated into a cap (see FIG.14), attached to a strap or other harness (not shown), and / or held in place. With further reference to FIG.14, when attached to a cap, the mechanism 100 may be attached such that the majority of the body 140 is positioned under the cap (e.g., between the cap and the patient’s scalp) with only the projection 204 and second end 152 protruding therefrom.

[0070] One secured in place, the user may grasp the second end 152 of the mechanism 140 and rotate the mechanism 140 relative to the patient’s scalp in a clockwise direction. By doing so, the second segment 172 of the body 140 rotates relative to the first segment 168 which remains stationary relative to the patient’s scalp. As discussed above, the relative rotation between the two segments 168, 172 causes the pins 216 of each comb element 112 to travel along a corresponding slot 212 forcing each comb element 112 to translate axially outwardly away from the central axis 156 as a unit (e.g., cause each element 112 to move from its first position to its second position). While doing so, the teeth 228 of the comb features 230 of each comb element 112 pulls any hairs it is in contact with outwardly away from the central axis 156 and out of the sensing region 116.

[0071] To the extent any hairs remain in the sensing zone 116, the user is then free to cycle through the “clearing cycle” as needed until the sensing zone 116 is sufficiently clear of hairs. To do so, the user first rotates the second end 152 in a counter-clockwise direction (e.g., to return the comb elements 112 to their corresponding first positions as discussed above), and thenAttorney Docket No. 093386-0044-WO01 rotates the second end 152 in a clockwise direction (e.g., to cause the comb elements 112 to travel radially outwardly back to their second positions).

[0072] After the sensing zone 116 is sufficiently clear, the optode 104 may be installed by inserting the sensing tip 136 into the second end 152 of the probe channel 160 and securing the optode in place 104 so that the sensing axis 136 of the optode 104 is co-axial with the central axis 156. The optode 104 may then be used to collect data from the patient as is known in the art. Experimentation

[0073] Hair characterization - Methods

[0074] To determine hair length, we collected three strands of hair from the mannequin or participant’s scalp. The three strands were pulled from different locations within the target fNIRS imaging region: one strand was pulled from the medial portion of the scalp (or Cz location according to the international 10–10 optode layout), whereas the other two were pulled from the left (C3) and right (C4) lateral regions of the scalp. Each strand was collected noninvasively by plucking or cutting at the root. For length measurement, each hair strand was straightened by taping down the ends of the strand to a piece of white paper, and we used a measuring tape to determine the end-to-end length. We calculated the average of the three strand lengths to represent the hair length of the participant.

[0075] To determine shaft thickness, we applied a micrometer to each of the three hair strands we collected. We ensured the hair strands were not compressed during this process by incrementally tightening the micrometer until the strand could not be removed from the micrometer via gravity. We averaged the three values we collected to record a representative shaft thickness for the participant.

[0076] To determine the curl or coil of the hair, we followed a similar procedure outlined by Loussouarn. The Loussouarn group developed and utilized a classification diagram that rates curl on a scale of one to four, which corresponds with a hair type description commonly utilized by cosmetologists. The diagram contains four curves that correspond to each of the hair types and is shown in FIG.8(a). To measure curliness, we took a strand of hair and placed it in the area labeled “IV” on the diagram. If the hair strand could not be contained inside of the boundary, itAttorney Docket No. 093386-0044-WO01 was moved outward to the next area labeled “III.” This movement of the hair was repeated until the hair strand was appropriately contained in a labeled area, and the labeled area corresponded to the representative hair type, which was recorded.

[0077] To measure density, we consulted the three locations on the participant’s scalp from which hair strands were collected previously in the procedure. We used hair clips to noninvasively part the hair at each of the three locations and placed a 3D-printed window measuring 3 ×3 mm onto each part, which is shown in FIG. 8(b). We utilized a macro lens (Xenvo, Clarus 15x) to take an image of the hair contained in the square and manually counted the number of hair strands observed.12 We normalized this measurement by recording the density in units of hair strands per square millimeter. We averaged the three hair density values to record a representative value.

[0078] To measure color, we utilized a color spectrum and chose the color that blended best with the participant’s hair. We accomplished this visually by comparing the participant’s hair to each color option on the spectrum and recorded the number that matched most closely. The color spectrum is shown in FIG.8(c).

[0079] Mannequin testing - Methods

[0080] To test the utility of the various extrusion designs and confirm the optimal extrusion design for each hair type, we measured the clearance achieved with eight unique sliding leg extrusions on ten wigged mannequins of various hair characteristics. Wigged mannequins varied in hair length, shaft thickness, curl or coil, density, and hair color, though hair color was not a significant factor in hair clearance on mannequins. To create the wigged mannequin population, we utilized one bald mannequin head and 10 wigs.

[0081] The hair manipulation mechanism 100, containing one of the eight comb members (FIGS.7A-H), was incorporated into a commercial fNIRS cap system (Brite MKII) without optodes, which were excluded so that we could evaluate the effectiveness of the mechanism 100 for clearance. The cap system was placed on the wigged mannequin head, and the mechanism 100 was applied to the C3, Cz, and C4 locations, associated with the international 10–10 optode layout, then twisted to clear the hair. We chose these optode locations because they are locatedAttorney Docket No. 093386-0044-WO01 on the human motor cortex, which is typically a hair-covered region probed during finger- tapping exercises that are commonly used in neuroimaging studies to assess cognitive activity. At each location, three clearance trials were performed, and the cleared hair was imaged and passed through a MATLAB script. The image was captured with the 8-megapixel main camera on the Samsung Galaxy Tablet A7 Lite and was cropped so that only the 10.3-mm circular area cleared by the mechanism 100 was visible. The image was then uploaded to the script that displayed the image and prompted the user to interactively select five pixels on the image that represented the scalp. The image was then converted to grayscale, and the grayscale intensity values at the selected scalp pixels were compiled. The largest intensity value of these pixels then became the intensity threshold in the script, meaning that any pixel with an intensity greater than this value was considered hair, and any pixel with an intensity lower than this value was considered scalp. Each pixel in the image was then binarily identified as either a hair strand or a scalp. The number of nonzero pixels, which represent the scalp, was used to calculate the percent of hair clearance achieved. This process was repeated for all combinations of wigged mannequins and sliding leg extrusions.

[0082] Human testing - Methods

[0083] Following mannequin testing, we recruited a total of 15 participants to partake in two data collection procedures to evaluate the effectiveness of the mechanism 100 in two respects: one related to the time needed to create clearance and one related to the signal quality captured with an fNIRS system. Based on the results from mannequin testing that provided optimal hair clearance effectivity pairs, we determined which sliding leg design was appropriate for each participant.

[0084] Clearance timing - Methods

[0085] The purpose of this procedure was to determine whether the mechanism 100 offers an advantage in system setup time over existing methodologies. To perform this validation, we compared the time required to create hair clearance with the mechanism 100 and an external tool, a plastic screwdriver, which is typically used to create hair clearance in fNIRS procedures. We placed an fNIRS head cap on each participant’s head and recorded the amount of time needed to create hair clearance in five of nine optode openings across the motor cortex using the plasticAttorney Docket No. 093386-0044-WO01 screwdriver. We chose this optode split so the remaining four openings could be used as controls during the “fNIRS data collection” procedure. The optode layout is captured in FIG.9. We utilized a stopwatch to collect the clearance timing data. Once the fNIRS head cap was properly aligned on each participant, we began the timer and created hair clearance for five optode openings. When creating clearance with the mechanism 100, we repeatedly twisted the design until hair strands were cleared from the inner diameter of the mechanism 100, and the scalp was viewable in each opening. When using the plastic screwdriver, hair strands were moved out of the view of the optode opening again until the scalp was viewable. After this process was completed for each of the five openings, the timer was stopped, and the value was recorded.

[0086] We then repeated the cap placement and timing data collection steps a second time for each participant, but in the second trial, we created clearance with the mechanism 100. The hair clearance time (in seconds) recorded for the mechanism 100 included the time needed to create clearance in each optode opening via the twisting mechanism. The clearance timings for the mechanism 100 and plastic screwdriver were compared using a paired Student’s t-test.

[0087] fNIRS data collection - Methods

[0088] The purpose of this procedure was to compare the SNR and signal quality achievable with the use of the mechanism 100 compared with the use of the commonly used plastic screwdriver across different hair characteristics. Following each trial of the “clearance timing” procedure, we collected neuroimaging data from the Brite MKII fNIRS system by inserting probes into each of the nine cap openings. The Brite MKII system is a continuous-wave fNIRS system that operates at wavelengths of 760 and 850 nm. Five of the openings were cleared of hair with either the plastic screwdriver or the mechanism 100. As previously mentioned, four openings were not cleared of hair using either method, and we collected data from these openings to serve as a control for the SNR measurements. Once the openings in the cap system were populated with fNIRS system optodes, we collected data over a 7-min time frame consisting of a 2-min initial resting state followed by alternating 40-s stimulus blocks of finger tapping and 35-s rest periods. Once data were collected following hair clearance with the plastic screwdriver and mechanism 100, we extracted the SNR over the four 40-s stimulus blocks of the finger-tapping procedure and computed the average for each block. The SNR was calculated viaAttorney Docket No. 093386-0044-WO01 the following equation where represents the signal intensity offset and represents the signal variance. =20 log

[0089] We performed statistical analysis across the three clearance methodologies using two- way analysis of variance (ANOVA) testing and paired t-tests and used Bonferroni correction to address the multiple comparison problem.

[0090] Mannequin Testing - Results

[0091] The results of the hair clearance tests from “mannequin testing” are shown in FIG. 10. As shown, the clearance variation is very large across different wig curl patterns, so we have highlighted the cell in each column corresponding to the highest clearance value for clarity. As noted, design B (see FIG. 7B) worked optimally for the wigged mannequins of hair types 1A and 2A. The dimensionality, spacing, and number of extrusions in design B (see FIG. B) were inspired by finetooth combs, which are often used on hair that has lower density and less curl / coil, such as the 1A and 2A wigs we tested. The tested mannequin with type 1A hair had comparatively low hair density. Typically, straighter hair is associated with greater hair density than hair with more curl / coil, and this trend is captured in the human participant data collected from the study. In future studies, a more representative wig for type 1A hair will be needed.

[0092] Design E (see FIG.7E) was inspired by the fine-tooth comb, but the extrusions were designed with more curvature. We believe this curvature allows for greater interaction with and, thus, more effective clearance in hair with more curl / coil or greater density, such as was the case with the 3A, 3B, and 3C wigs. Designs C (see FIG.7C) and D (see Fig. 7D) were inspired by wide-tooth combs, which are commonly used on hair with greater shaft thickness and curl / coil. These designs were found to work optimally on the 2B and 2C wigs as, comparatively, these wigs had higher values of shaft thickness. Designs F, G, and H (see FIGS.7F, 7G, and 7H, respectively) worked optimally for hair types 4A, 4B, and 4C, respectively. Design F (see FIG. 7F) took inspiration from Denman combs, and designs F and G (see FIGS.7F and 7G, respectively) were inspired by pick combs. These standard comb designs are most often applied to hair with high levels of coil, such as what is seen in wigs 4A to 4C.Attorney Docket No. 093386-0044-WO01

[0093] Human Testing - Results

[0094] The results from hair characterization on the human testing participants were compiled and are shown in FIG.11. We considered and collected data related to color fromparticipants as it is a hair attribute that varies per person and influences fNIRS signal losshowever, hair color did not affect the sliding legs extrusion design chosen for each participant. The main hair characteristic that guided sliding leg design selection was the curl / coil pattern. We split our participant population into two groups: in the first group, all participants were matched with the optimal sliding leg design, whereas in the second group, all participants were assigned to use sliding leg design E, which was chosen as it showed the highest average level of hair clearance success across all wigged mannequins during “mannequin testing.” This grouping was performed to determine if the choice of the design of the comb-like extrusions influenced hair clearance results.

[0095] Clearance timing - Results

[0096] Across group 1, which was properly matched with the optimal sliding leg design based on participant hair type or curl / coil patterns, the average time for hair clearance using the plastic screwdriver was 33.4 s, whereas the average time using the mechanism 100 was 17.7 s. Using a paired t-test, we determined the mechanism 100 significantly (p < 0.005) reduced the average time needed to create hair clearance (FIG.12).

[0097] Findings from group 2. For group 2, we observed a slight decrease in average timing for both methods, but the mechanism 100 (15.6 s) remained significantly lower than the plastic screwdriver (31.0 s) according to a paired t-test (p < 0.005). The decrease in timing from groups 1 to 2 was likely caused by the researchers growing more accustomed to the hair-clearing process through repetition.

[0098] Clearance timing improvements with the mechanism 100

[0099] Across all participants, the mechanism 100 averaged 16.6 s to create hair clearance, whereas the plastic screwdriver required 32.1 s. We found that multiple twists (on the order of four twists), meaning twisting back and forth between fully closed and open configurations, were needed to create proper clearance and move the sliding legs completely out of the path of theAttorney Docket No. 093386-0044-WO01 system optodes, which increased the average clearance timing for the mechanism 100. In future iterations, we plan to investigate mechanism 100 design changes that improve the ease of movement of the Sliding legs to further reduce hair clearance time. Indeed, a robust, one-twist design would reduce the clearance time to under 5 s.

[0100] Although the use of the mechanism 100 comparatively offers a 15.5-s timing advantage per optode during hair clearance, we found the setup process for the mechanism 100 was more time-intensive. For the plastic screwdriver, the setup time comprises the amount of time needed to populate the cap with nine optode holders and position it atop the participant’s head. For the mechanism 100, this setup timing also included the amount of time required to assemble—connect the twistable cover, all sliding legs, and support piece—each of the nine mechanism 100. The average amount of time needed to assemble and incorporate the mechanism 100 was 7.1 min, which was significantly longer than the 1.7 min needed to prepare the cap system for use with the plastic screwdriver. Notably, the 5.4-min timing difference across setup and clearance will be overcome using the mechanism 100 if a study requires an imaging array with more than 21 optodes (15.5-s timing advantage per optode ×21 optodes = 5.4 min). Also, the steps required for mechanism 100 setup could be done prior to participant arrival, ideally via researchers pre-loading the cap system with the mechanism 100 sliding leg design of choice. We performed this pre-loading of the cap system for the second group of participants, where the sliding leg design was predetermined and found the mechanism 100 setup time decreased to 1.9 min on average.

[0101] fNIRS data collection

[0102] The average SNRs across group 1 were 55.6, 51.3, and 39.5 dB respectively for channels cleared of hair via the mechanism 100, the plastic screwdriver, and without hair clearance. We conducted ANOVA testing across the results from the three methodologies and found a significant (p < 0.01) difference between means. To determine which means are different, we performed paired t-tests. We found no significant difference (FIG.13) in SNR between the mechanism 100 and plastic screwdriver (p > 0.05), but we did observe that both the mechanism 100 (p < 0.01) and plastic screwdriver (p < 0.05) offered significant improvements in SNR in comparison with the control condition of no clearance. Across group 2, the average SNRAttorney Docket No. 093386-0044-WO01 achieved using the mechanism 100 with sliding leg design E decreased to a value of 53.0 dB. The SNR for the plastic screwdriver increased to a value of 53.9 dB, and the control condition of no clearance also increased to 43.1 dB. Similar to group 1, we conducted ANOVA testing across the results from the three methodologies (p < 0.05) followed by paired t-tests to determine the specific means that differed significantly. Using paired t-tests, we found no significant difference in SNR between the mechanism 100 and plastic screwdriver (p > 0.05) nor between the mechanism 100 and control condition (p > 0.05) when the sliding leg design was not matched to participant hair type. A significant relationship did exist between the plastic screwdriver and the control condition of no clearance (p < 0.05) for group 2 participants.

[0103] Similar to group 1, the general trends in SNR and hair type existed for group 2. The four participants with the greatest curl / coil characteristics (participants 12 to 15) had the four lowest recorded SNR values with the mechanism 100. Signal quality is improved when the mechanism 100 is properly matched to the participants. The increased SNR from groups 1 to 2 when using the plastic screwdriver can be partly attributed to the higher incidence of lighter- haired participants as the average shade of group 2 was approximately two shades lighter based on the hair color diagram used. The increased SNR can also be attributed to the researchers growing more accustomed to the hair clearance procedure as was discussed in the clearance timing results. Types 1A, 2A, and 3A were the only hair types present in both groups, and these hair types had a general increase in SNR from groups 1 to 2 results. Because group 2 data were collected later comparatively, the increased SNR was likely a partial result of the researchers learning how to more efficiently clear hair over the course of data collection. The decrease in average SNR for the mechanism 100 and loss of significance between the mechanism 100 SNR and control SNR from groups 1 to 2 can be attributed to the fact that most participants in group 2 were not properly paired to the hypothesized optimal sliding leg design, in comparison with group 1 where all were properly matched based on hair type or curl / coil characteristics. The three participants in group 2 who were truly matched for Design E (see FIG.7E) had, on average, longer and denser hair than those in group 1. This supports the hypothesis that a more complex model is needed to match participants with their optimal sliding leg design, rather than using only hair type as the criterion. Nevertheless, the mechanism 100 sliding leg design proved to offer similar SNR to existing, common methods for hair clearance while significantly reducing the clearance timing. Notably, a good signal was obtained even in participants with type 4 hair.Attorney Docket No. 093386-0044-WO01

[0104] Design Versatility Test

[0105] To demonstrate the versatility of the mechanism 100 to fit different systems, we created additional versions of the mechanism 100 that integrate with two other commercial systems: the fNIRS ETG 4000 (Hitachi Philips – Santa Clara, CA) and the NIRScout (NIRx – Berlin, Germany) systems. The optode sizes of both systems were unique and larger than that of the Brite MKII system. The mechanism 100 design was modified by adjusting the inner diameter of the twistable cover to fit each system. Figure 14 shows a top and bottom view of the mechanism 100 when incorporated into the Artinis (left), ETG 4000 (middle) and NIRScout (right) fNIRS systems.

[0106] In addition to modifying the inner diameter of the top of the twistable cover, the mechanism 100 design can be modified across numerous other parameters. To accommodate differing optode lengths, the height of each individual piece can be modified to allow for proper coupling between the optode and scalp. Currently, the mechanism 100 can be used to measure signal across channels greater than 24 mm in length, but to accommodate channels of shorter separation distance, the outer diameter of the support piece (currently measuring 24 mm as shown in FIG.4B) can be adjusted.

[0107] Because the mechanism 100 needs to be compatible with (i.e., not obstruct or cause damage to) electronics components present in all fNIRS systems, we chose to make them out of polylactic acid (PLA). PLA can be easily cleaned and disinfected, is durable enough to be used repeatedly, and it can be constructed quickly via 3D printing. The design also needed to make comfortable contact with the participant’s scalp. Comb-like extrusions that are too sharp or rigid could damage or scratch to the scalp. Additionally, application of pressure to the scalp could cause hair loss or alopecia. Because some fNIRS imaging procedures can span multiple hours in duration, this prolonged pressure is a significant concern. To address these concerns, we developed a soft interface for the comb features. The soft interface was formed by coating the extrusions with an approximately one-mm-thick layer of Dragon Skin FX-Pro silicone, which is a soft, skin- and biosafe silicone rubber.

[0108] Wigged mannequin population and results from hair characterizationAttorney Docket No. 093386-0044-WO01

[0109] To create the wigged mannequin population, we utilized one bald mannequin head and ten wigs (FIG.15). All wigs were supplied with a netting headcap that was placed on the mannequin first. Each wig was then placed on the mannequin’s head by attaching a clip on the wig to the netting headcap and covering the entire netting area. To ensure the wig was firmly on the mannequin, we gently shook the mannequin head and observed for any moment in the wig location. If movement occurred, we reattached the wig to the netting and repeated the process. The hair characteristics of each wigged mannequin were determined by the characterization process previously mentioned across three locations (C3, Cz, and C4) standardized by the 10-10 international optode layout. The hair length, shaft thickness, curl / coil, and density measurements were averaged across the three locations to account for imperfections in the wigs.

[0110] At each location, three clearance trials were performed, and the cleared hair was photographed and passed through a Matlab script used to quantify the amount of clearance created. Between the three individual clearance trials, the hair that was cleared was adjusted to mimic the initial setting of the wig to ensure that no clearance effects remained for future trials.

[0111] The full wigged mannequin population is pictured in FIG.15A. The results from hair characterization on the wigged mannequins appear in FIG.15B. The tested wigged mannequins covered a wide spectrum of hair characteristic combinations, as shown by the values in the table. Wigged mannequins also varied in hair color, though hair color was not a significant factor in hair clearance on mannequins.

[0112] Post hoc, we tested two additional wigged mannequins to (1) ensure that at least one loose-haired mannequin was tested for each hair type and (2) observe how hair clearance is affected when hair type is held constant and other hair characteristics are allowed to change. The two mannequins tested had Type 4A hair and are shown in FIG. 16. Using the same hair clearance procedure as described for the original ten wigged mannequins, we found that the optimal sliding leg design differed for each of the three Type 4A wigs. The optimal sliding leg design pairs were Design F (see FIG.7F) for Mannequin 8, Design H (see FIG.7H) for Mannequin 11, and Design G (see FIG. 7G) for Mannequin 12. These results support the point detailed in the Discussion section that a more complex model should be used to properly match sliding leg designs with hair populations, whether mannequin or human, to create the optimalAttorney Docket No. 093386-0044-WO01 amount of clearance. Based on the results shown in FIG.16, both hair density and strand thickness should more heavily influence sliding leg design selection in future studies.

[0113] Mannequin testing hair clearance quantification

[0114] The images used to quantify hair clearance in the wigged mannequin population were captured with the 8-megapixel main camera on the Samsung Galaxy Tab A7 Lite and was cropped so that only the 10.3-mm circular area cleared by the mechanism 100 was visible. The images were then uploaded to the script that displayed the image and prompted the user to interactively select five pixels on the image that represented the scalp. The images were then converted to grayscale, and the grayscale intensity values at the selected scalp pixels were compiled. The largest intensity value of these pixels then became the intensity threshold in the script, meaning that any pixel with intensity greater than this value was considered hair and any pixel with intensity lower than this value was considered scalp. Each pixel in the image was then binarily identified as either hair strand or scalp. The number of nonzero pixels, which represent scalp, was used to calculate the percent of hair clearance achieved. The pipeline of the Matlab script is contained in FIG.17.

Claims

Attorney Docket No. 093386-0044-WO01 CLAIMS:

1. A hair manipulation mechanism for manipulating one or more hairs on an entity, the hair manipulation mechanism comprising: abody defining a central axisa plurality of comb elements, wherein each comb element includes at least one legextending therefrom that is configured to engage the one or more hairs of the entity andwherein each comb element of the plurality of comb elements is adjustable between a first position, in which the comb element is spaced a first radial distance from the central axis, and a second position, in which the comb element is spaced a second radial distance from the central axis greater than the first distance.

2. The hair manipulation mechanism of claim 1, wherein the hair manipulation mechanism is operable in a first configuration, in which each comb element of the plurality of comb elements is in its corresponding first position, and a second configuration, in which each comb element of the plurality of comb elements is in its corresponding second position.

3. The hair manipulation mechanism of claim 2, wherein the body includes a first portion and a second portion movable with respect to the first portion, and wherein moving the first portion relative to the second portion is configured to cause the hair manipulation mechanism to change between the first and second configurations.

4. The hair manipulation mechanism of claim 3, wherein the first portion is rotatable with respect to the second portion about the central axis.

5. The hair manipulation mechanism of claim 1, wherein the first radial distance is the same for each comb element of the plurality of comb elements.

6. The hair manipulation mechanism of claim 1, wherein the second radial distance is the same for each comb element of the plurality of comb elements.Attorney Docket No. 093386-0044-WO01 7. The hair manipulation mechanism of claim 1, wherein the leg extending from at least one comb element extends in an axial direction.

8. The hair manipulation mechanism of claim 1, wherein the leg extending from at least one comb element extends radially outwardly.

9. The hair manipulation mechanism of claim 1, wherein the body includes a first portion and a second portion rotatable with respect to the first portion about the central axis, and wherein rotating the first portion relative to the second portion is configured to cause at least a portion of the plurality of comb elements to move between their respective first and second positions.

10. The hair manipulation mechanism of claim 1, wherein the body defines a channel extending therethrough, and wherein the channel is co-axially aligned with the central axis.

11. The hair manipulation mechanism of claim 10, wherein the channel is configured for an fNIRS optode to be coupled thereto.

12. The hair manipulation mechanism of claim 1, wherein the plurality of comb elements are spaced equally over 360 degrees about the central axis of the body.

13. A hair manipulation mechanism for attachment to an optode, the hair manipulation mechanism comprising: a body defining a central axis, wherein the body includes a first portion and a secondportion movable with respect to the first portiona plurality of comb elements, wherein each comb element includes a tooth extendingtherefrom andwherein moving the first portion with respect to the second portion is configured to cause each comb element to move radially with respect to the central axis.Attorney Docket No. 093386-0044-WO01 14. The hair manipulation mechanism of claim 13, wherein the first portion is rotatable with respect to the second portion about the first axis, and wherein rotating the first portion in a first direction relative to the second portion is configured to cause each comb element to move radially outwardly away from the central axis.

15. The hair manipulation mechanism of claim 14, wherein rotating the first portion in a second direction opposite to the first direction relative to the second portion is configured to cause each comb element to move radially inwardly toward the central axis.

16. The hair manipulation mechanism of claim 13, wherein the first portion of the body defines a plurality of spiral grooves, and wherein each comb element of the plurality of comb elements includes a protrusion at least partially positioned within a corresponding spiral groove.

17. The hair manipulation mechanism of claim 13, wherein when the first portion of the body is stationary relative to the second portion each of the comb elements are radially fixed relative to the central axis.

18. The hair manipulation mechanism of claim 13, wherein the body defines a channel extending therethrough, wherein the channel is co-axial with the central axis, and wherein each comb elements is movable radially between a first position wherein at least a portion of the comb element is positioned within the channel, and a second position, in which the comb element is not positioned within the channel.

19. A hair manipulation mechanism for attachment to an optode, the hair manipulation mechanism comprising: abody defining a channel extending therethrougha first comb element movable with respect to the body, wherein the first comb elementincludes a tooth extending therefroma second comb element movable with respect to the body, wherein the second combelement includes a tooth extending therefrom andAttorney Docket No. 093386-0044-WO01 wherein the hair manipulation mechanism is adjustable between a first configuration, in which the first and second comb elements are at least partially positioned within the channel, and a second configuration, in which the first and second comb elements are not positioned within the channel.

20. The hair manipulation mechanism of claim 19, wherein the first comb element is spaced a first distance from the second comb element in the first configuration, and wherein the first comb element is spaced a second distance greater than the first distance from the second comb element in the second configuration.

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