Field effect transistor based wearable biosensors for healthcare monitoring.

The rapid advancement of wearable biosensors has revolutionized healthcare monitoring by screening in a non-invasive and continuous manner. Among various sensing techniques, field-effect transistor (FET)-based wearable biosensors attract increasing attention due to their advantages such as label-free detection, fast response, easy operation, and capability of integration. This review explores the innovative developments and applications of FET-based wearable biosensors for healthcare monitoring. Beginning with an introduction to the significance of wearable biosensors, the paper gives an overview of structural and operational principles of FETs, providing insights into their diverse classifications. Next, the paper discusses the fabrication methods, semiconductor surface modification techniques and gate surface functionalization strategies. This background lays the foundation for exploring specific FET-based biosensor designs, including enzyme, antibody and nanobody, aptamer, as well as ion-sensitive membrane sensors. Subsequently, the paper investigates the incorporation of FET-based biosensors in monitoring biomarkers present in physiological fluids such as sweat, tears, saliva, and skin interstitial fluid (ISF). Finally, we address challenges, technical issues, and opportunities related to FET-based biosensor applications. This comprehensive review underscores the transformative potential of FET-based wearable biosensors in healthcare monitoring. By offering a multidimensional perspective on device design, fabrication, functionalization and applications, this paper aims to serve as a valuable resource for researchers in the field of biosensing technology and personalized healthcare.

Evaluation of the World Health Organization standard tourniquet test and a modified tourniquet test in the diagnosis of dengue infection in Viet Nam.

OBJECTIVES: A positive tourniquet test is one of several clinical parameters considered by the World Health Organization to be important in the diagnosis of dengue haemorrhagic fever, but no formal evaluation of the test has been undertaken. As many doctors remain unconvinced of its usefulness, this study was designed to assess the diagnostic utility of both the standard test and a commonly employed modified test. METHODS: A prospective evaluation of the standard sphygmomanometer cuff tourniquet test, compared with a simple elastic cuff tourniquet test, was carried out in 1136 children with suspected dengue infection admitted to a provincial paediatric hospital in southern Viet Nam. RESULTS: There was good agreement between independent observers for both techniques, but the sphygmomanometer method resulted in consistently greater numbers of petechiae. This standard method had a sensitivity of 41.6% for dengue infection, with a specificity of 94.4%, positive predictive value of 98.3% and negative predictive value of 17.3%. The test differentiated poorly between dengue haemorrhagic fever (45% positive) and dengue fever (38% positive). The simple elastic tourniquet was less sensitive than the sphygmomanometer cuff, but at a threshold of 10 petechiae (compared with the WHO recommendation of 20) per 2.5 cm2 the sensitivity for the elastic tourniquet rose to 45% (specificity 85%). Other evidence of bleeding was frequently present and the tourniquet test provided additional information to aid diagnosis in only 5% of cases. CONCLUSION: The conventional tourniquet test adds little to the diagnosis of dengue in hospitalized children. The simple, cheap elastic tourniquet may be useful in diagnosing dengue infection in busy rural health stations in dengue endemic areas of the tropics. A positive test should prompt close observation or early hospital referral, but a negative test does not exclude dengue infection.