Eye sensors

The 3,5-dinitrophenyl derivatives of pyrrole 2,5-diamide 4 [15] acted as a selective naked-eye sensor for F" in MeCN solution, which gives rise to a deep blue color (Amax=598 nm). This color change was due to a deprotonation process caused by F" acting as a base and subsequent charge-transfer interactions between the deprotonated pyrrole and the nitroaromatic groups. 

Recently, Sessler and coworkers [32] have synthesized a quinoxaline-bridged porphyrinoid 35 that can be used as a naked-eye sensor for F . Upon addition of F" to a 10% DMSO CH2Cl2 solution of compound 35, the color of the solution changed from pale orange ( =427 nm) to red (Amax=480 nm) with... 

Triarylbenzoamido-crown ethers 71 and 72 [58] showed abilities as naked-eye sensors for F, H2PO4, AcO , citrate, trimesate, and isophthalate in the presence of potassium picrate in DMS0 H20 (1 1 v/v). Upon addition of the aforementioned anions to a solution of 71-K+ or 72-K+ picrate, the color of the solution changed from yellow to green. 

More recently, a new class of covalent-linked calix[4]pyrrole-anthraquinone compounds (29-31) have been introduced by Sessler s group [48], These are considered to be powerful naked eye sensors for fluoride, chloride and dihydrogen phosphate ions in dichloromethane. The most pronounced colour change was observed upon the addition of the fluoride anion into a solution of the receptor 30 in dichloromethane. The addition of bromide, iodide or nitrate anions did not lead to significant colour changes. 

They re the latest in high-tech faucetry hands-free water-savers, equipped with electronic-eye sensors that automatically detect hands and dispense preset amounts of water. They re also more likely to be contaminated with one of the most common and hazardous bacteria in hospitals compared to old-style fixtures with separate handles for hot and cold water, according to researchers at Johns Hopkins Hospital. 

Khoo. I. C., 1996. US Patent 5,589,101, Liquid crystal fiber array for optical limiting of laser pulses and for eye/sensor protection. Issued 31 December 1996. 

Built-In Solar Eye sensors measure the light Intensity and transmit the data to the Solar Eye controller. 

Laser alignment systems use a transmitter and receiver. The system has a laser diode and a position sensor on a bracket mounted on one shaft that emits a weak and safe radio-tagged beam of light. The light ray is directed toward the other bracket on the other shaft with a reflecting prism that returns the ray back toward the first bracket into the position sen.sor eye. 

Photomultipliers are appreciably more sensitive sensors than the eye in their response to line or continuum sources. Monochromators are fitted to the light beam in order to be able to operate as substance-speciflcally as possible [5]. Additional filter combinations (monochromatic and cut-off filters) are needed for the measurement of fluorescence. Appropriate instruments are not only suitable for the qualitative detection of separated substances (scanning absorption or fluorescence along the chromatogram) but also for characterization of the substance (recording of spectra in addition to hR and for quantitative determinations. 

Manual Controls. The first methods used in energy control involved human intei vention. The operator was the sensor (i.e., using his eyes, ears, and hands or using additional devices to quantify the values of the controlled variables), and he was also the actuator controller. The control of the processes was slow and vei y ineffective. For example, in an old steam engine control the human operator sees the instantaneous pressure and then manually regulates the power of the device (e.g., by adding fuel to a boiler). But in today s industrial reality, this control is not only ineffective but in most cases is not possible. 

Levels, tapes, thermometers, hydrometers, light meters, smoke detectors, audio-sensors. Features such as cradle rails, safety eyes and climbing irons should be incorporated into the design of the building. 

CCD sensor which, in these regions, is usually higher than the sensitivity of the human eye. For comparison, the wavelength dependence of the response of human eye and the CCD camera used at IPCF is shown in figure 9. 

Figure 9. Spectral sensitivity of human eye (at the top) vs. IPCF CCD sensor (at the bottom).

To replace the old-fashioned eye-control method of detecting the level of the liquid, appliance manufacturers now use reed sensors to show when the container for Jet-Dry needs refilling. The reed sensor is mounted underneath, or next to, the liquid container. A floater with an internal permanent magnet is placed in the container and floats on the liquid. If its level falls to a minimum, the floater activates the reed sensor which, in turn, activates a light on the front control panel of the dishwasher, signaling the need to refill the Jet-Dry container. 

Nonlinear optical organic materials such as porphyrins, dyes, and phthalocyanines provide optical limiting properties for photonic devices to control light frequency and intensity in a predictable manner. The optical limit of CNTs composites is saturated at CNTs exceeding 3.8wt% relative to the polymer mass (Chen et al., 2002). Polymer/ CNT composites could also be used to protect human eyes, for example, optical elements, optical sensors, and optical switching (Cao et al., 2002). 

Optical sensors have the advantage of an easily measured signal that can be seen by the naked eye in some cases. Optical detection methods include fluorescence, surface plasmon resonance spectroscopy, Raman, IR, and chemiluminescence (Fabbrizzi and Poggi 1995 deSilva et al. 1997). However, the fabrication and development of optical MIP sensors requires that a colored, emissive, or fluorescent monomer... 

The human body, for instance, has sensors (eyes, ears, touch receptors in the skin, and so forth), a controller (the brain), and actuators (muscles) to react and respond to commands. These are the same basic concepts as the adaptive systems discussed in this chapter. Robots today, such as the welding machines used in industry or the toy dogs sold as pets, are extremely Umited in mobility and adaptability compared to humans. Yet smart materials, along with a design based on the sensory, nervous, and muscular systems of the body, could one day create an agile and adaptable robot. 

The predictive power of the luminescent PET sensor principle is again apparent here. Further, the benzocrown ether and the amine receptors would selectively bind Na" and H, respectively. A remarkable feature here is that no molecular wiring is needed to allow the human operation of this two-input molecular device. The device self-selects its own ion inputs into the appropriate signal channels by means of the chemoselective receptor modules. Since the output signal is fluorescence, even a single molecule can interface with detectors in the human domain, including the dark-adapted eye. Tanaka s 45 is another example where fluorescence quenching is achieved only when Ba and SCN are present. This was mentioned in Section 6. Similarly, several sensor systems—1,17, and 21—could be employed... 

B. M. Cordero, and M. Forina, Electronic Nose Based on Metal Oxide Semiconductor Sensors as a Fast Alternative for the Detection of Adulteration of Virgin Olive Oils, Anal. Chim. Acta 2002,459, 219 C. L. Honeyboume, Organic Vapor Sensors for Food Quality Assessment, J. Chem. Ed. 2000, 77, 338 E. Zubritsky, E-Noses Keep an Eye on the Future. Anal. Chem. 2000, 72. 

Crown ethers of the type discussed in this section have been used as sensors, membranes, or materials for chromatography. Shinkai used cholesterol-substituted crown ether 10 as a sensor for chirality in chiral ammonium compounds (Scheme 16). It was found that the pitch of the cholesteric phase exhibited by 10 was changed upon addition of the chiral salt. As the wavelength of reflection for incident light depends on the pitch, a color change was observed that was visible to the naked eye [45, 46]. Such chirality sensing systems were known before but chromophores had to be bound to the crown ether in order to observe color changes [47]. This problem could be overcome by 10, which uses intrinsic properties of the chiral nematic phase. 

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