The authors have no acknowledgments.

1. Design
<ol>
	<li>See Figure 1 for details of the development drawing.</li>
	<li>Cut a 3-mm thick acrylic board to 210 mm in width x 60 mm in height x 104 mm in depth, bond with acrylic adhesive and assemble the case.</li>
	<li>Install as many as 30 optical cells of 12.5 x 12.5 mm.</li>
	<li>Attach switches and lamps for starting and stopping and a variable dial for the drying time setting on the front face of the casing.</li>
	<li>See Figure 2 for an external view and component configuration.</li>
	<li>Use acrylic and nylon for the casing and net, respectively. Fix the net to the frame and attach it to the upper part of the case.</li>
	<li>Use acrylic for the lattice of the optical-cell installation. Attach it to the top of the net.</li>
	<li>Mount the blowers to the back of the case.</li>
	<li>Use translucent acrylic for a waterdrop prevention partition.</li>
</ol>
2. Hardware Design Outline
<ol>
	<li>See Figure 3 for details of the circuit diagram.</li>
	<li>Step down from 12 V to 5 V by a three-terminal regulator for operating the microcomputer.</li>
	<li>Activate the blowers via an NPN transistor (25 V, 500 mA). 
	Note: Because the output pin of the microcomputer is 5 V.</li>
	<li>Control the rotation speed of the blowers by the pulse width modulation (PWM) operation of the output pin. 
	Note: The blower is being driven, the number of revolutions is controlled, and the strength is periodically changed.</li>
	<li>Connect the start push switch to the digital input pin.</li>
	<li>Connect the blowers&#8217; operation time setting volume to the analog input pin to change the voltage according to the rotational position.</li>
	<li>Connect the organic light-emitting diode (OLED) for the operation time display to the two digital output pins with an inter-integrated circuit (I2C).</li>
	<li>Connect the LED that lights up during the operation to the digital output pin.</li>
</ol>
3. Software Design Outline
<ol>
	<li>Use a microcomputer to control the blowers. 
	Note: The development environment was constructed using Arduino, which is one of the development environments called open-source hardware, and all circuits and software are open to the public.</li>
	<li>Outline of the operation
	<ol>
		<li>Press the start switch.</li>
		<li>Read the state of the button specified by the select button on the front and activate the blower according to that state.</li>
		<li>Read the drying time set by the variable resistor on the front as a voltage signal and start counting down the timer.</li>
		<li>Turn the LED lights up and display the remaining time on the OLED.</li>
	</ol>
	</li>
	<li>Detailed explanation
	<ol>
		<li>Read the volume position connected to the analog input pin as a voltage; then, it converts to the blower&#8217;s operation time and displays on the OLED.</li>
		<li>Detect the ON/OFF switch connected to J1-9, 10 pins of the circuit diagram when pressing the start switch, turn on the blowers&#8217; drive pin, activate the blowers, and turn on the LED during the operation.</li>
		<li>Control the blowers by PWM. Detect the position of the 10-k&#937; variable resistor connected to the circuit diagram J1-5, 6, 7, and drive the blowers with the corresponding output.</li>
		<li>Detect the position of the 10-k&#937; variable resistor connected to the circuit diagrams J1-1, 2, 3 pin by setting the drying time and activate the blowers for a time corresponding to that.</li>
		<li>Connect the power LED to the circuit diagrams J1-15, 16 pin. Connect the start LED to the circuit diagrams J1 - 12, 13. 
		Note: The power LED lights up when the power turns on, and the start LED lights up while the blowers are activated.</li>
		<li>Connect the OLED to PB4, PB5 of the CPU with an I2C. 
		Note: The operation time displayed on the OLED is counted down every second. When the operation time reaches 0, the blowers&#8217; drive pin is set to 0, the blowers are stopped, and the operating LED is turned off to make the transition to the initial standby state.</li>
		<li>Use the Adafruit SSD1306 library for an OLED display of Arduino. 
		Note: When the power switch is turned ON, operate in the order of initialization and message display. A part of the source code is shown below as an example of use of this library. 
		#include &#34;Wire.h&#34;; 
		#include &#60;Adafruit_SSD1306.h&#62; 
		#define OLED_RESET -1 
		Adafruit_SSD1306 display(OLED_RESET); 
		<img alt="Equation" src="/files/ftp_upload/58518/58518eq1.jpg" /> 
		<img alt="Equation" src="/files/ftp_upload/58518/58518eq1.jpg" /> 
		void setup() { 
		Serial.begin(115200); 
		while (!Serial) { 
		; // wait for serial port to connect. Needed for Leonardo only 
		} 
		Wire.begin(SDA, SCL); // (SDA, SCL) 
		delay(1000); 
		display.clearDisplay(); // Clear the buffer. 
		display.setTextSize(1); 
		display.clearDisplay(); 
		display.print(F(&#34;SD &#34;)); // Weake Up Message Display(Version) 
		display.println(ver); 
		display.display(); 
		<img alt="Equation" src="/files/ftp_upload/58518/58518eq1.jpg" /> 
		<img alt="Equation" src="/files/ftp_upload/58518/58518eq1.jpg" /> 
		}</li>
	</ol>
	</li>
</ol>
4. Method of Operation
<ol>
	<li>See Figure 2 for details of the External View.</li>
	<li>Turn the main power switch of number 10 ON. The operation lamp of number 11 lights up.</li>
	<li>Place the optical cells on the mesh number 2 from the lattice part of the plastic of number 1. 
	Note: The number of optical cells that can be mounted is as many as the number of lattices.</li>
	<li>Select a two-blower operation or four-blower operation. Depending on the driving situation, the operation lamp of number 5 and number 6 lights up. 
	Note: Number 3 is a switch for operating the blowers on the right side, and number 4 is a switch for operating the blowers on the left side.</li>
	<li>Set the operation time with the timer with number 9.</li>
	<li>Turn number 7 on. 
	Note: The fan with number 12 starts, and, at the same time, the operation lamp of number 8 lights up.</li>
</ol>
5. Method to Measure the Drying Time
<ol>
	<li>In the case of natural drying
	<ol>
		<li>Wash the optical cells thoroughly with water or ethanol. Use thick absorbent paper to absorb the moisture of the optical cells, then move the cells to another place on the thick absorbent paper and wait until they dry.</li>
	</ol>
	</li>
	<li>In the case of the optical-cell dryer
	<ol>
		<li>Wash the optical cells thoroughly with water or ethanol. 
		Note: Use thick absorbent paper to temporarily absorb the moisture.</li>
		<li>Place the optical cells in the optical-cell dryer, then wait until they are dry.</li>
		<li>Measure the drying time 3x for each cell.</li>
	</ol>
	</li>
	<li>Comparison of the average values 
	<ol>
		<li>Measure the drying times 3x at 30 places to obtain the distribution. 
		Note: This is to detect the time difference according to the position of the cells in the optical-cell dryer.</li>
		<li>Use average values of all 30 places for a comparison with water. 
		Note: In the case of washing with water, determine the positions of the optical cells randomly, then measure the drying time at 10 points.</li>
	</ol>
	</li>
</ol>

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The authors have nothing to disclose.

The optical cells can be dried simultaneously with the blowers, and the drying time can be considerably reduced. Even if the stop operation is not executed, it can be safely stopped by using the automatic stop function of the timer. From the measurement results of the drying time distribution, there was no significant difference in drying time because of the difference in the installation position of the optical cells.
A critical step of the protocol is the design of the casing. The challenge ...

Optical cells are used as laboratory instruments in a wide range of fields. In life science research, biomolecules such as nucleic acids and proteins are often utilized for experiments, and spectroscopic methods are widely used for quantitative methods. Accurately quantifying the sample of the experiment is indispensable for obtaining more accurate and reproducible results. The absorption spectrum obtained by a spectrophotometer has often been used for the quantification of biomolecules such as nucleic acids and proteins1,2,3,4. Research on oxidation-reduction characteristics caused by the change in the absorption spectrum and photoluminescence of a carbon nanotube (CNT) dispersed using DNA has also been conducted5,6,7,8,9,10. Optical cells are used for these measurements, but accurate measurements cannot be made unless they are thoroughly washed and dried.
When measuring absorption spectra or photoluminescence, it is impossible to measure precisely in dirty optical cells11,12,13,14,15. Economical disposable optical cells made of polystyrene and poly-methyl-methacrylate are also used to eliminate washing and contamination. However, when precise measurements are required, quartz glasses are often used, because they have extremely excellent optical properties such as light transmittance. In this case, the optical cells are washed after the measurement of the sample and repeatedly used. Usually, after washing optical cells with water or ethanol, they are dried naturally. When rapid drying is required, they are dried one by one by using hair dryers or similar equipment. Cleaning optical cells is one of the most unpleasant and time-consuming procedures in the experiment. As the number of samples increases, the drying time increases, which, in turn, increases the time required to conduct the experiment and research. In past studies, there have been no reports on peripheral devices of optical cells. This study aims to reduce the research time by drying multiple optical cells simultaneously.
We investigated whether other similar products exist. A box-type constant temperature dryer with a temperature control function and a timer function already exists; however, no commercial products with the same configuration can be found.
An outline of the production of this device is described. First, the box-type case is made using an acrylic plate. Nylon netting is attached to the top. A plastic grid is placed on it to fix the optical cell. The control circuit is stored inside the case, and the plastic plate is attached to protect the circuit from water droplets. The control circuit consists of a CPU and is controlled by software. Blowers are attached to the back of the case, and the wind supplied by the blowers enters the optical cells set upside down. The blowers are activated by a switch on the front, and they are automatically stopped by the timer. Depending on the number of optical cells to be dried, two or four blowers can be selected for operation. Water droplets dripping from the optical cells evaporate with the wind from the blowers. The quartz cells are washed with water or ethanol, and the drying time is compared with that of natural drying.

<table><tbody><tr><td>blower</td><td>ebm-papst</td><td>422JN</td><td>Mulfingen, Germany</td></tr><tr><td>Microcomputer</td><td>Atmel Corporation</td><td>ATmega 328 P</td><td>CA, USA</td></tr><tr><td>Blower selection button</td><td>Sengoku Densyo Co., Ltd.</td><td>MS-358 (red)</td><td>Tokyo, Japan</td></tr><tr><td>Blower operationg lamp</td><td>Akizuki Denshi Tsusho Co., Ltd.</td><td>DB-15-T-OR</td><td>Tokyo, Japan</td></tr><tr><td>Blower start button</td><td>Sengoku Densyo Co., Ltd.</td><td>MS-350M (white)</td><td>Tokyo, Japan</td></tr><tr><td>Timer</td><td>Akizuki Denshi Tsusho Co., Ltd.</td><td>SH16K4A105L20KC</td><td>Tokyo, Japan</td></tr><tr><td>Power supply switch</td><td>Marutsuelec Co., Ltd.</td><td>3010-P3C1T1G2C01B02BKBK-EI</td><td>Tokyo, Japan</td></tr><tr><td>Power supply lamp</td><td>Akizuki Denshi Tsusho Co., Ltd.</td><td>DB-15-T-G</td><td>Tokyo, Japan</td></tr><tr><td>OLED module</td><td>Akihabara Co., Ltd.</td><td>M096P4W</td><td>Tokyo, Japan</td></tr></tbody></table>

fabrication of an optical cell dryer for the spectroscopic analysis cells

Optical cells, which are experimental instruments, are small, square tubes sealed on one side. A sample is placed in this tube, and a measurement is performed with a spectroscope. The materials used for optical cells generally include quartz glass or plastic, but expensive quartz glass is reused by removing substances, other than liquids, to be analyzed that adhere to the interior of the container. In such a case, the optical cells are washed with water or ethanol and dried. Then, the next sample is added and measured. Optical cells are dried naturally or with a manual hairdryer. However, drying takes time, which makes it one of the factors that increase the experiment time. In this study, the objective is to drastically reduce the drying time with a dedicated automatic dryer that can dry multiple optical cells at once. To realize this, a circuit was designed for a microcomputer, and the hardware using it was independently designed and manufactured.

As shown in Table 1, in the case of ethanol washing, the average drying time in natural drying was 426.4 s, and the average drying time in the optical-cell dryer was 106 s. In the case of water washing, the average drying time in natural drying was 1481.4 s, and the average drying time in the optical-cell dryer was 371.6 s. In both cases, the drying time was reduced to approximately one-fourth. The drying time distribution of the optical-cell dryer is shown in <strong cla...

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Fabrication of an Optical Cell Dryer for the Spectroscopic Analysis Cells

A protocol for fabricating a device for simultaneously drying multiple optical cells is presented.

Optical cells, which are experimental instruments, are small, square tubes sealed on one side. A sample is placed in this tube, and a measurement is ...

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5.1K Views.  Tokyo University of Science. A protocol for fabricating a device for simultaneously drying multiple optical cells is presented.

Video: Fabrication of an Optical Cell Dryer for the Spectroscopic Analysis Cells

Implementation of a Reference Interferometer for Nanodetection

A thermally and mechanically stabilized fiber interferometer suited for examining ultra-high quality factor microcavities is fashioned. After assessing its free spectral range (FSR), the module is put in parallel with a fiber taper-microcavity system and then calibrated through isolating and eliminating random shifts in the laser frequency (i.e. laser jitter noise). To realize the taper-microcavity junction and to maximize the optical power that is transferred to the resonator, a single-mode optical fiber waveguide is pulled. Solutions containing polystyrene nanobeads are then prepared and flown to the microcavity in order to demonstrate the system&#8217;s ability to sense binding to the surface of the microcavity. Data is post-processed via adaptive curve fitting, which allows for high-resolution measurements of the quality factor as well as the plotting of time-dependent parameters, such as resonant wavelength and split frequency shifts. By carefully inspecting steps in the time-domain response and shifting in the frequency-domain response, this instrument can quantify discrete binding events.

A reference interferometer technique, which is designed to remove undesirable laser jitter noise for nanodetection, is utilized for probing an ultra-high quality factor microcavity. Instructions for assembly, setup, and data acquisition are provided, alongside the measurement process for specifying the cavity quality factor.

A thermally and mechanically stabilized fiber interferometer suited for examining ultra-high quality factor microcavities is fashioned. After assessing ...

Fabrication and Testing of Microfluidic Optomechanical Oscillators

Cavity optomechanics experiments that parametrically couple the phonon modes and photon modes have been investigated in various optical systems including microresonators. However, because of the increased acoustic radiative losses during direct liquid immersion of optomechanical devices, almost all published optomechanical experiments have been performed in solid phase. This paper discusses a recently introduced hollow microfluidic optomechanical resonator. Detailed methodology is provided to fabricate these ultra-high-Q microfluidic resonators, perform optomechanical testing, and measure radiation pressure-driven breathing mode and SBS-driven whispering gallery mode parametric vibrations. By confining liquids inside the capillary resonator, high mechanical- and optical- quality factors are simultaneously maintained.

Parametric optomechanical excitations have recently been experimentally demonstrated in microfluidic optomechanical resonators by means of optical radiation pressure and stimulated Brillouin scattering. This paper describes the fabrication of these microfluidic resonators along with methodologies for generating and verifying optomechanical oscillations.

Cavity optomechanics experiments that parametrically couple the phonon modes and photon modes have been investigated in various optical systems including ...

Fabrication and Operation of a Nano-Optical Conveyor Belt

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological and physical sciences over the past few decades. The progress made in this field invites further study of even smaller systems and at a larger scale, with tools that could be distributed more easily and made more widely available. Unfortunately, the fundamental laws of diffraction limit the minimum size of the focal spot of a laser beam, which makes particles smaller than a half-wavelength in diameter hard to trap and generally prevents an operator from discriminating between particles which are closer together than one half-wavelength. This precludes the optical manipulation of many closely-spaced nanoparticles and&#160;limits the&#160;resolution of optical-mechanical systems. Furthermore, manipulation using focused beams requires beam-forming or steering optics, which can be very bulky and expensive. To address these limitations in the system scalability of conventional optical trapping our lab has devised an alternative technique which utilizes near-field optics to move particles across a chip. Instead of focusing laser beams in the far-field, the optical near field of plasmonic resonators produces the necessary local optical intensity enhancement to overcome the restrictions of diffraction and manipulate particles at higher resolution. Closely-spaced resonators produce strong optical traps which can be addressed to mediate the hand-off of particles from one to the next in a conveyor-belt-like fashion. Here, we describe how to design and produce a conveyor belt using a gold surface patterned with plasmonic C-shaped resonators and how to operate it with polarized laser light to achieve super-resolution nanoparticle manipulation and transport. The nano-optical conveyor belt chip can be produced using lithography techniques and easily packaged and distributed.

The scalability and resolution of conventional optical manipulation techniques are limited by diffraction. We circumvent the diffraction limit and describe a method of optically transporting nanoparticles across a chip using a gold surface patterned with a path of closely spaced C-shaped plasmonic resonators.

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological ...

Fabrication of High Contrast Gratings for the Spectrum Splitting Dispersive Element in a Concentrated Photovoltaic System

High contrast gratings are designed and fabricated and its application is proposed in a parallel spectrum splitting dispersive element that can improve the solar conversion efficiency of a concentrated photovoltaic system. The proposed system will also lower the solar cell cost in the concentrated photovoltaic system by replacing the expensive tandem solar cells with the cost-effective single junction solar cells. The structures and the parameters of high contrast gratings for the dispersive elements were numerically optimized. The large-area fabrication of high contrast gratings was experimentally demonstrated using nanoimprint lithography and dry etching. The quality of grating material and the performance of the fabricated device were both experimentally characterized. By analyzing the measurement results, the possible side effects from the fabrication processes are discussed and several methods that have the potential to improve the fabrication processes are proposed, which can help to increase the optical efficiency of the fabricated devices.

The fabrication of high contrast gratings as the parallel spectrum splitting dispersive element in a concentrated photovoltaic system is demonstrated. Fabrication processes including nanoimprint lithography, TiO2 sputtering and reactive ion etching are described. Reflectance measurement results are used to characterize the optical performance.

High contrast gratings are designed and fabricated and its application is proposed in a parallel spectrum splitting dispersive element that can improve ...

A Simple Dewar/Cryostat for Thermally Equilibrating Samples at Known Temperatures for Accurate Cryogenic Luminescence Measurements

The design and operation of a simple liquid nitrogen Dewar/cryostat apparatus based upon a small fused silica optical Dewar, a thermocouple assembly, and a CCD spectrograph are described. The experiments for which this Dewar/cryostat is designed require fast sample loading, fast sample freezing, fast alignment of the sample, accurate and stable sample temperatures, and small size and portability of the Dewar/cryostat cryogenic unit. When coupled with the fast data acquisition rates of the CCD spectrograph, this Dewar/cryostat is capable of supporting cryogenic luminescence spectroscopic measurements on luminescent samples at a series of known, stable temperatures in the 77-300 K range. A temperature-dependent study of the oxygen quenching of luminescence in a rhodium(III) transition metal complex is presented as an example of the type of investigation possible with this Dewar/cryostat. In the context of this apparatus, a stable temperature for cryogenic spectroscopy means a luminescent sample that is thermally equilibrated with either liquid nitrogen or gaseous nitrogen at a known measureable temperature that does not vary (&#916;T &#60; 0.1 K) during the short time scale (~1-10 sec) of the spectroscopic measurement by the CCD. The Dewar/cryostat works by taking advantage of the positive thermal gradient dT/dh that develops above liquid nitrogen level in the Dewar where h is the height of the sample above the liquid nitrogen level. The slow evaporation of the liquid nitrogen results in a slow increase in h over several hours and a consequent slow increase in the sample temperature T over this time period. A quickly acquired luminescence spectrum effectively catches the sample at a constant, thermally equilibrated temperature.

A simple liquid nitrogen Dewar/cryostat apparatus comprised of a small fused silica optical Dewar, a thermocouple, and a charge-coupled device (CCD) spectrograph are described. The experiments for which this Dewar/cryostat is designed require fast sample loading, freezing, and alignment, accurate and stable sample temperatures, and small size/portability.

The design and operation of a simple liquid nitrogen Dewar/cryostat apparatus based upon a small fused silica optical Dewar, a thermocouple assembly, and ...

Design and Fabrication of an Optical Fiber Made of Water

In this report, an optical fiber of which the core is made solely of water, while the cladding is air, is designed and manufactured. In contrast with solid-cladding devices, capillary oscillations are not restricted, allowing the fiber walls to move and vibrate. The fiber is constructed by a high direct current (DC) voltage of several thousand volts (kV) between two water reservoirs that creates a floating water thread, known as a water bridge. Through the choice of micropipettes, it is possible to control the maximal diameter and length of the fiber. Optical fiber couplers, at both sides of the bridge, activate it as an optical waveguide, allowing researchers to monitor the water fiber capillary body waves through transmission modulation and, therefore, deducing changes in surface tension.
Co-confining two important wave types, capillary and electromagnetic, opens a new path of research in the interactions between light and liquid-wall devices. Water-walled microdevices are a million times softer than their solid counterparts, accordingly improving the response to minute forces.

This protocol describes the design and manufacture of a water bridge and its activation as a water fiber. The experiment demonstrates that capillary resonances of the water fiber modulate its optical transmission.

In this report, an optical fiber of which the core is made solely of water, while the cladding is air, is designed and manufactured. In contrast with ...

Multicolor Fluorescence Detection for Droplet Microfluidics Using Optical Fibers

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as multiplex assays, enzyme evolution, and molecular biology enhanced cell sorting require the detection of two or more colors of fluorescence. Standard multicolor detection systems that couple free space lasers to epifluorescence microscopes are bulky, expensive, and difficult to maintain. In this paper, we describe a scheme to perform multicolor detection by exciting discrete regions of a microfluidic channel with lasers coupled to optical fibers. Emitted light is collected by an optical fiber coupled to a single photodetector. Because the excitation occurs at different spatial locations, the identity of emitted light can be encoded as a temporal shift, eliminating the need for more complicated light filtering schemes. The system has been used to detect droplet populations containing four unique combinations of dyes and to detect sub-nanomolar concentrations of fluorescein.

Multicolor fluorescence detection in droplet microfluidics typically involves bulky and complex epifluorescence microscope-based detection systems. Here we describe a compact and modular multicolor detection scheme that utilizes an array of optical fibers to temporally encode multicolor data collected by a single photodetector.

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as ...

Bioengineering

Methods for the Self-integration of Megamolecular Biopolymers on the Drying Air-LC Interface

Living organisms that use water are always prone to drying in the environment. Their activities are driven by biopolymer-based micro- and macro-structures, as seen in the cases of moving water in vascular bundles and moisturizing water in skin layers. In this study, we developed a method for assessing the effect of aqueous liquid crystalline (LC) solutions composed of biopolymers on drying. As LC biopolymers have megamolecular weight, we chose to study polysaccharides, cytoskeletal proteins, and DNA. The observation of biopolymer solutions during drying under polarized light reveals milliscale self-integration starting from the unstable air-LC interface. The dynamics of the aqueous LC biopolymer solutions can be monitored by evaporating water from a one-side-open cell. By analyzing the images taken using cross-polarized light, it is possible to recognize the spatio-temporal changes in the orientational order parameter. This method can be useful for the characterization of not only artificial materials in various fields, but also natural living tissues. We believe that it will provide an evaluation method for soft materials in the biomedical and environmental fields.

A method for the drying-induced self-integration of megamolecular biopolymers on the air-liquid crystalline interface is provided here. This methodology will be useful not only for understanding the macroscopic potentials of biopolymers, but also as an evaluation method for soft materials in biomedical and environmental fields.

Living organisms that use water are always prone to drying in the environment. Their activities are driven by biopolymer-based micro- and ...

Fabrication of a Fabry-P&#233;rot Etalon for Application in Trace-Gas Spectroscopy

Fabrication of a Low-Cost, Fiber-Coupled, and Air-Spaced Fabry-P&#233;rot Etalon

Fabry-P&#233;rot etalons (FPE) have found their way into many applications. In fields such as spectroscopy, telecommunications, and astronomy, FPEs are used for their high sensitivity as well as their exceptional filtering capability. However, air-spaced etalons with high finesse are usually built by specialized facilities. Their production requires a clean room, special glass handling, and coating machinery, meaning commercially available FPEs are sold for a high price. In this article, a new and cost-effective method to fabricate fiber-coupled FPEs with standard photonic laboratory equipment is presented. The protocol should serve as a step-by-step guide for the construction and characterization of these FPEs. We hope this&#160;will enable researchers to conduct fast and cost-effective prototyping of FPEs for various fields of application. The FPE, as presented here, is used for spectroscopic applications. As shown in the representative results section via proof of principle measurements of water vapor in ambient air, this FPE has a finesse of 15, which is sufficient for the photothermal detection of trace concentrations of gases.

Author Spotlight: Fabrication of a Low-Cost, Fiber-Coupled, and Air-Spaced Fabry-P&#233;rot Etalon  

This protocol describes the construction of a low-cost, discrete, fiber-coupled, and air-spaced Fabry-Perot etalon with various applications, such as in trace-gas spectroscopy. The fabrication is possible in any facility with standard optical laboratory equipment available.

Fabry-P&#233;rot etalons (FPE) have found their way into many applications. In fields such as spectroscopy, telecommunications, and astronomy, FPEs are ...

Direct Analysis of Single Cells by Mass Spectrometry at Atmospheric Pressure

Analysis of biochemicals in single cells is important for understanding cell metabolism, cell cycle, adaptation, disease states, etc. Even the same cell types exhibit heterogeneous biochemical makeup depending on their physiological conditions and interactions with the environment. Conventional methods of mass spectrometry (MS) used for the analysis of biomolecules in single cells rely on extensive sample preparation. Removing the cells from their natural environment and extensive sample processing could lead to changes in the cellular composition. Ambient ionization methods enable the analysis of samples in their native environment and without extensive sample preparation.1 The techniques based on the mid infrared (mid-IR) laser ablation of biological materials at 2.94 &mu;m wavelength utilize the sudden excitation of water that results in phase explosion.2 Ambient ionization techniques based on mid-IR laser radiation, such as laser ablation electrospray ionization (LAESI) and atmospheric pressure infrared matrix-assisted laser desorption ionization (AP IR-MALDI), have successfully demonstrated the ability to directly analyze water-rich tissues and biofluids at atmospheric pressure.3-11 In LAESI the mid-IR laser ablation plume that mostly consists of neutral particulate matter from the sample coalesces with highly charged electrospray droplets to produce ions. Recently, mid-IR ablation of single cells was performed by delivering the mid-IR radiation through an etched fiber. The plume generated from this ablation was postionized by an electrospray enabling the analysis of diverse metabolites in single cells by LAESI-MS.12 This article describes the detailed protocol for single cell analysis using LAESI-MS. The presented video demonstrates the analysis of a single epidermal cell from the skin of an Allium cepa bulb. The schematic of the system is shown in Figure 1. A representative example of single cell ablation and a LAESI mass spectrum from the cell are provided in Figure 2.

Single cell analysis is performed by mass spectrometry on plant and animal cells at atmospheric pressure by using a sharpened optical fiber to sample the cells for laser ablation electrospray ionization (LAESI) mass spectrometry.

Analysis of biochemicals in single cells is important for understanding cell metabolism, cell cycle, adaptation, disease states, etc. Even the same cell ...