{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T04:05:41Z","timestamp":1790654741763,"version":"4.1.0"},"reference-count":43,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2019,4,1]],"date-time":"2019-04-01T00:00:00Z","timestamp":1554076800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This study develops a hand-held stress assessment meter with a chemically colorimetric strip for determining salivary \u03b1-amylase activity, using a 3,5 dinitrosalicylic acid (DNS) assay to quantify the reducing sugar released from soluble starch via \u03b1-amylase hydrolysis. The colorimetric reaction is produced by heating the strip with a mini polyester heater plate at boiling temperature to form a brick red colored product, which measured at 525 nm wavelength. This investigation describes in detail the design, construction, and performance evaluation of a hand-held \u03b1-amylase activity colorimeter with a light emitted diode (LED) and photo-detector with built-in filters. The dimensions and mass of the proposed prototype are only 120 \u00d7 60 \u00d7 60 mm3 and 200 g, respectively. This prototype has an excellent correlation coefficient (&gt;0.995), comparable with a commercial ultraviolet\u2013visible spectroscope, and has a measurable \u03b1-amylase activity range of 0.1\u20131.0 U mL\u22121. The hand-held device can measure the salivary \u03b1-amylase activity with only 5 \u03bcL of saliva within 12 min of testing. This sensor platform effectively demonstrates that the level of salivary \u03b1-amylase activity increases more significantly than serum cortisol, the other physiological stressor biomarker, under physiologically stressful exercise conditions. Thus, this work demonstrates that the hand-held \u03b1-amylase activity meter is an easy to use and cost-effective stress assessment tool for psychoneuroendocrinology research.<\/jats:p>","DOI":"10.3390\/s19071571","type":"journal-article","created":{"date-parts":[[2019,4,2]],"date-time":"2019-04-02T03:21:26Z","timestamp":1554175286000},"page":"1571","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":25,"title":["Hand-held Colorimetry Sensor Platform for Determining Salivary \u03b1-Amylase Activity and Its Applications for Stress Assessment"],"prefix":"10.3390","volume":"19","author":[{"given":"Hsien-Yi","family":"Hsiao","sequence":"first","affiliation":[{"name":"Department of Bio-industrial Mechatronics Engineering, College of Bio-Resources and Agriculture, National Taiwan University, Taipei 100617, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Richie L. C.","family":"Chen","sequence":"additional","affiliation":[{"name":"Department of Bio-industrial Mechatronics Engineering, College of Bio-Resources and Agriculture, National Taiwan University, Taipei 100617, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chih-Chi","family":"Chou","sequence":"additional","affiliation":[{"name":"Department of Bio-industrial Mechatronics Engineering, College of Bio-Resources and Agriculture, National Taiwan University, Taipei 100617, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tzong-Jih","family":"Cheng","sequence":"additional","affiliation":[{"name":"Department of Bio-industrial Mechatronics Engineering, College of Bio-Resources and Agriculture, National Taiwan University, Taipei 100617, Taiwan"},{"name":"Department of Biomedical Engineering, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei 10002, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2019,4,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"486","DOI":"10.1016\/j.psyneuen.2009.01.014","article-title":"Salivary alpha-amylase as a non-invasive biomarker for the sympathetic nervous system: Current state of research","volume":"34","author":"Nater","year":"2009","journal-title":"Psychoneuroendocrinology"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"469","DOI":"10.1016\/j.psyneuen.2008.12.004","article-title":"Determinants of salivary \u03b1-amylase in humans and methodological considerations","volume":"34","author":"Rohleder","year":"2009","journal-title":"Psychoneuroendocrinology"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"157","DOI":"10.1111\/j.1600-0838.2010.01252.x","article-title":"An update: Salivary hormones and physical exercise","volume":"21","author":"Gatti","year":"2011","journal-title":"Scand. 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