Molecular recognition of organic solvents and ammonia: shapes and donor properties as sensor effects

Dickert, Franz L.; Haunschild, A.; Hofmann, Peter; Mages, G.

doi:10.1016/0925-4005(92)80025-s

Cited by 33 publications

(14 citation statements)

References 6 publications

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“…1 and 2, introduced us to the idea that future LC research could enhance our understanding of interactions between liquid crystal and other soft matter structures; potentially even leading us to the development of flexible, nonelectronic fiber textiles useful for the detection of harmful volatile gases. While the idea of using LC phase forming molecules as alternatives for developing layperson, user-friendly gas sensors is not so new [3][4][5][6][7] -ones which would also have form-factor versatility without the need for bulky equipment-the challenges for actually developing such materials that live up to these expectations, while simultaneously being able to endure environmental factors, have not been so trivial to overcome. Although the successful development of polymer dispersed liquid crystal (PDLC) surfaces have enriched the knowledge in determining how composites of polymers and liquid crystals can be successfully combined, still too little for too long has been known about the more chemical and thermodynamical interactions of LCs in more complex environments.…”

Section: Introductionmentioning

confidence: 99%

Advancing flexible volatile compound sensors using liquid crystals encapsulated in polymer fibers

Lagerwall

2018

Emerging Liquid Crystal Technologies XIII

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Until recently, organic vapor sensors using liquid crystals (LCs) have employed rigid glass substrates for confining the LC, and bulky equipment for vapor detection. Previously, we demonstrated that coaxially electrospinning nematic LC within the core of polymer fibers provides an alternative and improved form factor for confinement. This enables ppm level sensitivity to harmful industrial organics, such as toluene, while giving the flexibility of textile-like sheets (imparted by polymer encapsulation). Moreover, toluene vapor responses of the LC-core fiber mats were visible macroscopically with the naked eye depending on the morphology of the fibers produced, and whether they were oriented in specific geometries (aligned, or random). We identified two types of responses: one corresponds to the LC transition from nematic to isotropic, and the other we suggest is due to an anchoring change at the LC-polymer interface that influences the alignment. While we need to study the presence that defects can have in more detail, we noted that fiber mat thickness is crucial in attempting to understand how and why we are able to visualize two responses in aligned LC-fiber mats. Ultimately, we noted that the response of the polymer sheath itself (softening) to organic vapor exposure affects the liquid crystal confinement in the core. From the microscopic point of view, this will influence the threshold concentration that fibers in a mat will overall respond to. In this paper we will discuss three findings the morphologies enabling LC-core fiber mat response to vapor seen both micro-and macroscopically, how thickness of the fiber mat can play a role in the visualization of the responses, and the effect that the polymer structure has in the mat's sensitivity threshold.

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Section: Introductionmentioning

confidence: 99%

Advancing flexible volatile compound sensors using liquid crystals encapsulated in polymer fibers

Lagerwall

2018

Emerging Liquid Crystal Technologies XIII

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“…Recent studies have sought to realize chemical sensors based on LCs by using combinations of chemically tailored surfaces and LCs in order to engineer highly selective adsorbate-induced ordering transitions in the LCs. We also note that cholesteric LCs have been used for chemical sensing (with a change of pitch occurring upon absorption of an analyte), but approaches to chemical sensing based on cholesteric LCs lie beyond the scope of this chapter [5][6][7][8][9][10][11][12][13][14]. Finally, a number of studies with LCs as biological sensors have been reported over the past decade; however, we do not attempt to address those advances but rather refer the interested reader to relevant literature [15][16][17][18][19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Liquid Crystal‐Based Chemical Sensors

Hunter

Abbott

2012

Liquid Crystals Beyond Displays

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“…Past studies have demonstrated the utilization of CLCs as a colorimetric method for detecting VOCs. [27][28][29][30][31][32][33] A CLC gives colorimetric responses to VOCs because dissolution of VOCs in the CLC creates a net torque which affects the rotation of CLC molecules along their helical axis. 34 Consequently, it changes the pitch of the CLC and results in colorimetric responses.…”

Section: Introductionmentioning

confidence: 99%

Monitoring spatial distribution of ethanol in microfluidic channels by using a thin layer of cholesteric liquid crystal

Sutarlie

Yang

2011

Lab Chip

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Monitoring spatial distribution of chemicals in microfluidic devices by using traditional sensors is a challenging task. In this paper, we report utilization of a thin layer of cholesteric liquid crystal for monitoring ethanol inside microfluidic channels. This thin layer can be either a polymer dispersed cholesteric liquid crystal (PDCLC) layer or a free cholesteric liquid crystal (CLC) layer separated from the microfluidic device by using a thin film of PDMS. They both show visible colorimetric responses to 4% of ethanol solution inside the microfluidic channels. Moreover, the spatial distribution of ethanol inside the microfluidic channel can be reflected as a color map on the CLC sensing layers. By using this device, we successfully detected ethanol produced from fermentation taking place inside the microfluidic channel. These microfluidic channels with embedded PDCLC or embedded CLC offer a new sensing solution for monitoring volatile organic compounds in microfluidic devices.

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Molecular recognition of organic solvents and ammonia: shapes and donor properties as sensor effects

Cited by 33 publications

References 6 publications

Advancing flexible volatile compound sensors using liquid crystals encapsulated in polymer fibers

Advancing flexible volatile compound sensors using liquid crystals encapsulated in polymer fibers

Liquid Crystal‐Based Chemical Sensors

Monitoring spatial distribution of ethanol in microfluidic channels by using a thin layer of cholesteric liquid crystal

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