High optode-density wearable diffuse optical probe for monitoring paced breathing hemodynamics in breast tissue

Significance: Diffuse optical imaging (DOI) provides in vivo quantification of tissue chromophores such as oxy- and deoxyhemoglobin ([Formula: see text] and HHb, respectively). These parameters have been shown to be useful for predicting neoadjuvant treatment response in breast cancer patients. However, most DOI devices designed for the breast are nonportable, making frequent longitudinal monitoring during treatment a challenge. Furthermore, hemodynamics related to the respiratory cycle are currently unexplored in the breast and may have prognostic value. Aim: To design, fabricate, and validate a high optode-density wearable continuous wave diffuse optical probe for the monitoring of breathing hemodynamics in breast tissue. Approach: The probe has a rigid-flex design with 16 dual-wavelength sources and 16 detectors. Performance was characterized on tissue-simulating phantoms, and validation was performed through flow phantom and cuff occlusion measurements. The breasts of [Formula: see text] healthy volunteers were measured while performing a breathing protocol. Results: The probe has 512 unique source–detector (S-D) pairs that span S-D separations of 10 to 54 mm. It exhibited good performance characteristics: [Formula: see text] drift of 0.34%/h, [Formula: see text] precision of 0.063%, and mean [Formula: see text] up to 41 mm S-D separation. Absorption contrast was detected in flow phantoms at depths exceeding 28 mm. A cuff occlusion measurement confirmed the ability of the probe to track expected hemodynamics in vivo. Breast measurements on healthy volunteers during paced breathing revealed median signal-to-motion artifact ratios ranging from 8.1 to 8.7 dB. Median [Formula: see text] and [Formula: see text] amplitudes ranged from 0.39 to [Formula: see text] and 0.08 to [Formula: see text] , respectively. Median oxygen saturations at the respiratory rate ranged from 82% to 87%. Conclusions: A wearable diffuse optical probe has been designed and fabricated for the measurement of breast tissue hemodynamics. This device is capable of quantifying breathing-related hemodynamics in healthy breast tissue

Rotary fast tool servo component design

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1999.Includes bibliographical references (p. 185-188).This thesis covers the design and implementation of the components of a novel rotary fast tool servo (RFTS). The RFTS enables diamond turning of rotationally asymmet­ric optics, with an emphasis on eyeglass lenses. These components include the rotary arm which supports the cutting tool, a high resolution angular sensor for position feedback, and a labyrinth seal system to protect the rotary axis hearings. The design of the tool arm meets several conflicting challenges, including maintain­ing low rotational inertia and high stiffness while providing an integrated tool height adjustment mechanism. A new, novel "double-diaphragm" actuator is developed, which provides sub-micrometer level tool height adjustment. This actuator enables the tool arm to he constructed with little additional material, meeting the low inertia goals without compromising stiffness. The high resolution angular feedback hack sensor selected for the machine is a diffractive laser design. It was successfully interfaced into the machine, both mechanically and electrically, to provide ~ 10 nanometer resolution in cutting tool location. This was essential in enabling the RFTS to turn lenses with micrometer accuracy. Finally, a new possibility of developing rotational damping with a labyrinth hear­ing seal is explored. Rotational damping is created by exploiting the shear forces developed between a viscous fluid and a labyrinth with a fine gap size. This provides excellent sealing as well as rotational damping.by David Anthony Chargin.S.M