TY - JOUR
T1 - Photonic calcium and humidity array sensor prepared with reactive cholesteric liquid crystal mesogens
AU - Myung, Dan bi
AU - Hussain, Saddam
AU - Park, Soo Young
N1 - Publisher Copyright:
© 2019 Elsevier B.V.
PY - 2019/11/1
Y1 - 2019/11/1
N2 - Ion and humidity sensor array films have been developed using an interpenetrating polymeric network (IPN) of photonic networked cholesteric liquid crystals (CLCs) intertwined with network-structured poly(acrylic acid). Selective curing of a photonic CLC network film infiltrated with an acrylic acid/tri(propylene glycol) diacrylate mixture produced an array film of dots with photonic IPN structures on a simple photonic CLC background. Water isolation by individual hydrophilic dots against a hydrophobic background allowed testing of small sample amounts. Subsequent acetone/KOH treatments of the IPN film (IPNacetone/KOH film) prevented hydrogen bonding between carboxylic groups, maximized swelling of the film with water, and increased the speed of photonic color change. A full range of reflected colors, i.e., blue (dry) to red (humid), allows this film to act as an optical humidity sensor. The replacement of K+ with divalent ions that bridge the carboxylic groups prevented film swelling. Given that the photonic band gap wavelength is inversely proportional to the CaCl2 concentration, the amount of Ca2+ can be determined from the reflected color by the naked eye. This cost-effective, convenient IPNacetone/KOH film has been successfully applied as a biosensor for detecting Ca2+ in human blood serum and saliva and as an anti-counterfeiting label that reveals a colorful image under humid conditions.
AB - Ion and humidity sensor array films have been developed using an interpenetrating polymeric network (IPN) of photonic networked cholesteric liquid crystals (CLCs) intertwined with network-structured poly(acrylic acid). Selective curing of a photonic CLC network film infiltrated with an acrylic acid/tri(propylene glycol) diacrylate mixture produced an array film of dots with photonic IPN structures on a simple photonic CLC background. Water isolation by individual hydrophilic dots against a hydrophobic background allowed testing of small sample amounts. Subsequent acetone/KOH treatments of the IPN film (IPNacetone/KOH film) prevented hydrogen bonding between carboxylic groups, maximized swelling of the film with water, and increased the speed of photonic color change. A full range of reflected colors, i.e., blue (dry) to red (humid), allows this film to act as an optical humidity sensor. The replacement of K+ with divalent ions that bridge the carboxylic groups prevented film swelling. Given that the photonic band gap wavelength is inversely proportional to the CaCl2 concentration, the amount of Ca2+ can be determined from the reflected color by the naked eye. This cost-effective, convenient IPNacetone/KOH film has been successfully applied as a biosensor for detecting Ca2+ in human blood serum and saliva and as an anti-counterfeiting label that reveals a colorful image under humid conditions.
KW - Cholesteric liquid crystal
KW - Humidity sensor
KW - Interpenetrating polymeric network
KW - Optical sensor
UR - http://www.scopus.com/inward/record.url?scp=85069876311&partnerID=8YFLogxK
U2 - 10.1016/j.snb.2019.126894
DO - 10.1016/j.snb.2019.126894
M3 - Article
AN - SCOPUS:85069876311
SN - 0925-4005
VL - 298
JO - Sensors and Actuators, B: Chemical
JF - Sensors and Actuators, B: Chemical
M1 - 126894
ER -