{"id":118,"date":"2020-04-13T19:11:20","date_gmt":"2020-04-14T01:11:20","guid":{"rendered":"https:\/\/my.vanderbilt.edu\/nicolas2020\/?page_id=118"},"modified":"2020-04-20T11:27:40","modified_gmt":"2020-04-20T17:27:40","slug":"design","status":"publish","type":"page","link":"https:\/\/my.vanderbilt.edu\/nicolas2020\/design\/","title":{"rendered":"Our Design"},"content":{"rendered":"

Near-Infrared Spectroscopy (NIRS)<\/b><\/p>\n

\"Fig
Fig 1: NIRS LED\/Photoconductor Setup<\/figcaption><\/figure>\n

<\/b>Using the Modified Beer-Lambert\u2019s Law (Figure 2), our dual wavelength NIRS device converts raw voltage signal values to lactate concentrations ratiometrically.\u00a0 Utilizing this concept, our design focused IR light from the LED into the capillary bed of the finger, where it would be absorbed by lactic acid within the bloodstream.\u00a0 Then, any remaining non-absorbed light would be directed back into the photoconductor, where its intensity would be measured and compared to the input. This difference in\u00a0values would be related to, and could allow for the calculation of, circulating lactic acid concentration.<\/span><\/p>\n

\"Fig.
Fig. 2: Modified Beer-Lamberts Law for ratiometric NIRS<\/figcaption><\/figure>\n

Circuitry<\/strong><\/p>\n

\"Fig.
Fig. 3: LT-Spice Circuit Diagram of Device<\/figcaption><\/figure>\n

Design of the circuit involved developing optimal IR-light sensing modality, following traditional optical sensing methods.\u00a0 Main circuitry included the Thorlabs 1\u00b5m – 3\u00b5m photoconductor and two different Marktech IR-LEDs, one of 1650 nm and another at 1720 nm.\u00a0<\/span>We designed an LED-photoconductor optical system\u00a0<\/span>composed of 2 components: a pulsed current source (PCS) to drive the LED and a current to voltage (C2V) converter to read the photoconductor signal.<\/span><\/p>\n

 <\/p>\n

Phantom<\/b><\/p>\n

Several designs were considered as phantoms to represent the pertinent real-life properties of the finger. <\/span>At the outset, several design iterations included utilizing thin,\u00a0<\/span>IR-transparent catheters surrounded by various polymer mixtures that could approximately summarize the traits of the various layers of tissue from nail to vessel.\u00a0 Due to restraints of phantom dimensions and IR penetration depth, the design shifted to a more precise PDMS (polydimethylsiloxane) microfluidics phantom. To fulfill properties of blood, initial plans included\u00a0<\/span>increasing the complexity of lactate solutions with every successful absorbance trial.\u00a0 These solutions were, in order of increasing similarity to blood, were water, acetone, deuterated chloroform, PBS (phosphate buffered saline),\u00a0 FBS (fetal bovine serum), and ultimately defibrinated sheep blood.<\/span><\/p>\n

\"Fig.
Fig. 4: Phantom Model<\/figcaption><\/figure>\n

 <\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

Near-Infrared Spectroscopy (NIRS) Using the Modified Beer-Lambert\u2019s Law (Figure 2), our dual wavelength NIRS device converts raw voltage signal values to lactate concentrations ratiometrically.\u00a0 Utilizing this concept, our design focused IR light from the LED into the capillary bed of the finger, where it would be absorbed by lactic acid within the bloodstream.\u00a0 Then, any…<\/p>\n","protected":false},"author":8632,"featured_media":0,"parent":0,"menu_order":4,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"tags":[],"class_list":["post-118","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/my.vanderbilt.edu\/nicolas2020\/wp-json\/wp\/v2\/pages\/118","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/my.vanderbilt.edu\/nicolas2020\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/my.vanderbilt.edu\/nicolas2020\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/my.vanderbilt.edu\/nicolas2020\/wp-json\/wp\/v2\/users\/8632"}],"replies":[{"embeddable":true,"href":"https:\/\/my.vanderbilt.edu\/nicolas2020\/wp-json\/wp\/v2\/comments?post=118"}],"version-history":[{"count":5,"href":"https:\/\/my.vanderbilt.edu\/nicolas2020\/wp-json\/wp\/v2\/pages\/118\/revisions"}],"predecessor-version":[{"id":129,"href":"https:\/\/my.vanderbilt.edu\/nicolas2020\/wp-json\/wp\/v2\/pages\/118\/revisions\/129"}],"wp:attachment":[{"href":"https:\/\/my.vanderbilt.edu\/nicolas2020\/wp-json\/wp\/v2\/media?parent=118"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/my.vanderbilt.edu\/nicolas2020\/wp-json\/wp\/v2\/tags?post=118"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}