Detection of compounds in airborne particles using ion exchange

Abstract

A sensor (200) to detect a solid particle of a target salt can include a support substrate (210); an adsorption layer (240); a sensing layer (230) oriented between the support substrate (210) and the adsorption layer (240); and an electrode pair (220) in contact with and separated by the sensing layer (230). The adsorption layer (240) can include an ion exchange medium formed from a first porous structured material functionalized with a basic or acidic functional group. The basic or acidic functional group can remove an acid or base component from the target salt to form a free base or free acid, respectively, of the target salt. The sensing layer (230) can include a second porous structured material functionalized to detect the free base or acid of the target salt by a change in electrical conductivity.

Description

[0001] Related applications

[0002] This application claims the benefit of U.S. Provisional Application 63 / 014,879, filed April 24, 2020, which is incorporated herein by reference, and the benefit of U.S. Provisional Application 63 / 061,478, filed August 5, 2020, which is also incorporated herein by reference.

[0003] Government interests

[0004] This invention was completed with government support from the U.S. Department of Homeland Security, under grant numbers 70RSAT18C00000018 and 70RSAT19C00000016. The government enjoys certain rights in this invention. Background Technology

[0005] The increasing number of people addicted to opioids and the rising mortality rates from opioid abuse have led to opioid abuse becoming a public health emergency. For example, a sevenfold increase in fentanyl seizures or confiscations indicates that many overdose incidents can be caused by the availability of over-the-counter fentanyl. Doses as small as 2-3 mg can prove fatal to those exposed to fentanyl, including emergency responders. Fentanyl may be inhaled when responding to calls concerning fentanyl or other drugs that may be laced with it, putting first responders at risk of overdose. Current methods for identifying fentanyl require direct contact with the material. Non-contact methods are both expensive and cumbersome. Therefore, first responders would benefit from fentanyl identification devices that are wearable, do not require contact with the unknown substance, are highly sensitive, selective, generate results rapidly, and are low-cost.

[0006] More generally, determining the chemical composition of airborne particles is an ongoing challenge. For example, light-scattering-based smoke detectors cannot be placed in bathrooms because they cannot distinguish between smoke particles and water droplets (vapor).

[0007] Some methods used for detecting airborne chemicals include particle counters, chemical sensors, and analytical instruments. Particle counters typically use optical sensors to measure light scattering from any type of particle, including water droplets. This method typically detects all particles within a certain size range without any chemical composition information. Chemical sensors typically detect molecules via measurable signals (frequency, voltage, conductivity, etc.). Chemical sensors are generally insensitive to particles due to their small contact area. Many chemical sensors are housed in enclosures that prevent particles from reaching them. Analytical instruments typically detect molecules in the laboratory using spectrophotometry or spectroscopy techniques after sample preparation. Analytical methods, such as mass spectrometry, require expensive instruments ($100k) and sample preparation. In this method, particles are collected and then brought to the laboratory. The sample is then prepared by breaking down the particles into molecular components, for example, by laser ablation or chemical extraction. While this method is highly accurate and reliable, it is expensive, user-intensive, inconvenient to carry, and requires the user to be proficient in chemistry. Other techniques are based on Raman spectroscopy (e.g., Thermo Fisher Scientific (USA)). TM TRUNARC TM Handheld anesthetic analyzers are a portable technology suitable for detecting powders and does not require sample decomposition. However, these devices are not suitable for sensitive detection of airborne particles and are often expensive. Invention Overview

[0009] This disclosure describes sensors and methods for detecting solid particles of certain salts, such as salt forms of fentanyl. In some instances, a sensor for detecting solid particles of a target salt may include a supporting substrate; an adsorption layer; a sensing layer oriented between the supporting substrate and the adsorption layer; and an electrode pair contacting and separated from the sensing layer. The adsorption layer may include an ion exchange medium formed of a first porous structured material functionalized with basic or acidic functional groups. Basic functional groups can remove acidic components from the target salt to form a free base of the target salt. In the case of acidic functional groups, acidic functional groups can remove basic components from the target salt to form a free acid of the target salt. The sensing layer may include a second porous structured material functionalized to detect the free base or free acid of the target salt by changes in conductivity.

[0010] This disclosure also describes a method for detecting solid particles of a target salt. In one example, the method for detecting solid particles of a target salt may include exposing an adsorption layer to a gaseous medium in which particles of the target salt are entrained. The adsorption layer may include an ion exchange medium formed of a first porous structured material functionalized with basic or acidic functional groups. The basic or acidic functional groups may remove acid or base components from the target salt to form a free base or free acid of the target salt. The free base or free acid of the target salt may diffuse to a sensing layer adjacent to the adsorption layer. The sensing layer may include a second porous structured material functionalized to detect the free base or free acid of the target salt. In particular, the free base or free acid of the target salt may alter the conductivity of the second porous structured material. The method may also include measuring changes in the conductivity of the sensing layer using an electrode pair that is in contact with and separated from the sensing layer. The contact between the electrode pair and the sensing layer may be direct contact, although electrical contact through an intermediate conductor may also be used. In some examples, the gaseous medium may include air. In further examples, the free base can be vapor or gas. In some instances, the concentration of the target salt in the gaseous medium can range from 0.1 mg / m³. 3 Up to 100 mg / m 3 And in some cases, it is 1 mg / m² 3 Up to 4mg / m 3 .

[0011] Therefore, some features of the invention have been outlined rather extensively in order to better understand the following detailed description and to better appreciate the present contribution to the art. Other features of the invention will become clearer from the following detailed description, taken in conjunction with the accompanying drawings and claims, or by practice of the invention. Brief description of the attached diagram

[0013] Figure 1 This is a schematic side cross-sectional view of an example sensor according to the present disclosure.

[0014] Figure 2A-2D Schematic top and side cross-sectional views of an example sensor according to this disclosure are shown.

[0015] Figures 3A-3B Schematic top and side cross-sectional views of an example sensor according to this disclosure are shown.

[0016] Figures 4A-4F An overview of sensor operation during a fentanyl detection event is shown. Figure 4A -B) Fentanyl particles are introduced into the sensor. Figure 4C -D) Particles adsorb onto the alkali-functionalized nanofibers in the adsorption layer. When the particles contact the adsorption layer and interfere with the nanofibers, a small signal can be recorded. Figure 4E-F) Base-functionalized nanofibers induce ion exchange interactions with fentanyl salts, converting fentanyl molecules into their free base form. The free base fentanyl migrates, with a portion reaching the sensing layer, where it generates a signal through charge transfer.

[0017] Figure 5 This is a schematic diagram of another example sensor according to this disclosure.

[0018] Figures 6A-6D Bis(N-hexylamine) nanofibers were shown. Figure 6A ); Bis(N-ethylethylamine) nanofibers ( Figure 6B ); Bis(N-propylpropylamine) nanofibers ( Figure 6C ); Bis(N,N-dimethylbutylamine) Figure 6D Chemical structure and SEM images of ( ). All images are at the same scale.

[0019] Figure 7A This is an SEM image of the sensing layer nanofibers coated on the electrodes.

[0020] Figure 7B This is an SEM image of the sensing layer nanofibers after a second coating process using ethanol without any nanofibers.

[0021] Figure 8A and 8B This is a SEM image comparing the bis-NN-dimethylhexylamine adsorption layer and the nanofiber sensing layer.

[0022] Figure 8C This is a SEM image of a double layer with a mass of 1 μg adsorption layer.

[0023] Figure 8D These are SEM images of a bilayer at a mass of 3 μg adsorption layer. The sensing layer can be seen through the pores in the adsorption layer and is marked with circles. All images are at the same scale.

[0024] Figure 9A This is a SEM image of 1 μg of dibutylamine nanofibers on the sensing layer nanofibers. The included ellipse indicates the sensing layer nanofibers visible beneath the adsorption layer.

[0025] Figure 9B This is a SEM image of 3 μg of dibutylamine nanofibers on the sensing layer nanofibers.

[0026] Figure 9C These are SEM images of a single sensing layer nanofiber. All images are at the same scale.

[0027] Figure 10AThis is a SEM image of 1 μg of bis(N-ethylethylamine) nanofibers on the sensing layer nanofibers. The included ellipse indicates the sensing layer nanofibers visible beneath the adsorption layer.

[0028] Figure 10B This is a SEM image of 3 μg of bis(N-ethylethylamine) nanofibers on the sensing layer nanofibers.

[0029] Figure 10C These are SEM images of a single sensing layer nanofiber. All images are at the same scale.

[0030] Figure 11 Several example molecular structures used in sensing and adsorption layer nanofibers in several example sensor array cards are described.

[0031] Figure 12 Fentanyl and fentanyl analogues are shown: 1-fentanyl HCl, 2-norfentanyl HCl, 3-acrylamido-2-methyl-N-[1-(phenylmethyl)-4-piperidinyl], 4-acrylamido-N-[1-[2-(4-hydroxyphenyl)methyl]-4-piperidinyl]-N-phenyl, and 5-benzylfentanyl.

[0032] Figure 13A The experiment demonstrated the use of compound 2 as the sensing layer and compound 4 as the adsorption layer, exposing the sensor to 1-2 mg / m³. 3 Sensing results of the simulated material, in which 1 and 3 μg of adsorption layer material were used for the bilayer sensor.

[0033] Figure 13B The experiment demonstrated the use of compound 2 as the sensing layer and compound 4 as the adsorption layer, exposing the sensor to 2-4 mg / m³. 3 Sensing results of the simulated material, in which 1 and 3 μg of adsorption layer material were used for the bilayer sensor.

[0034] Figure 13C The experiment demonstrated the use of compound 2 as the sensing layer and compound 4 as the adsorption layer, exposing the sensor to 8-16 mg / m³. 3 Sensing results of the simulated material, in which 1 and 3 μg of adsorption layer material were used for the bilayer sensor.

[0035] Figure 14A The concentration dependence of the bilayer sensor using compound 2 as the sensing layer and compound 3 as the adsorption layer was shown.

[0036] Figure 14B The concentration dependence of the bilayer sensor using compound 2 as the sensing layer and compound 4 as the adsorption layer was shown.

[0037] Figure 14CThe concentration dependence of a bilayer sensor using compound 2 as the sensing layer and compound 5 as the adsorption layer was shown.

[0038] Figure 15 The fentanyl-cutting agent was shown, which was tested to determine the response from the interfering substance.

[0039] Figure 16A The control sensor containing only compound 2, the control sensor containing only compound 3, the compound 2 / 3 (1 μg) bilayer sensor, and the compound 2 / 3 (3 μg) bilayer sensor are shown for 10–20 mg / m³. 3 Sensor response of Metamizole.

[0040] Figure 16B The control sensor containing only compound 2, the control sensor containing only compound 4, the compound 2 / 4 (1 μg) bilayer sensor, and the compound 2 / 4 (3 μg) bilayer sensor are shown for 10–20 mg / m³. 3 Sensor response of aminopyrine.

[0041] Figure 16C The control sensor containing only compound 2, the control sensor containing only compound 5, the compound 2 / 5 (1 μg) bilayer sensor, and the compound 2 / 5 (3 μg) bilayer sensor are shown for 10–20 mg / m³. 3 Sensor response of aminopyrine.

[0042] Figure 17A The control sensor containing only compound 2, the control sensor containing only compound 3, the compound 2 / 3 (1 μg) bilayer sensor, and the compound 2 / 3 (3 μg) bilayer sensor are shown for 10–20 mg / m³. 3 Sensor response to mannitol.

[0043] Figure 17B The control sensor containing only compound 2, the control sensor containing only compound 4, the compound 2 / 4 (1 μg) bilayer sensor, and the compound 2 / 4 (3 μg) bilayer sensor are shown for 10–20 mg / m³. 3 Sensor response to mannitol.

[0044] Figure 17C The control sensor containing only compound 2, the control sensor containing only compound 5, the compound 2 / 5 (1 μg) bilayer sensor, and the compound 2 / 5 (3 μg) bilayer sensor are shown for 10–20 mg / m³. 3 Sensor response to mannitol.

[0045] Figure 18AThe control sensor containing only compound 2, the control sensor containing only compound 3, the compound 2 / 3 (1 μg) bilayer sensor, and the compound 2 / 3 (3 μg) bilayer sensor are shown for 10–20 mg / m³. 3 Sensor response to α-D-lactose.

[0046] Figure 18B The control sensor containing only compound 2, the control sensor containing only compound 4, the compound 2 / 4 (1 μg) bilayer sensor, and the compound 2 / 4 (3 μg) bilayer sensor are shown for 10–20 mg / m³. 3 Sensor response to α-D-lactose.

[0047] Figure 18C The control sensor containing only compound 2, the control sensor containing only compound 5, the compound 2 / 5 (1 μg) bilayer sensor, and the compound 2 / 5 (3 μg) bilayer sensor are shown for 10–20 mg / m³. 3 Sensor response to α-D-lactose.

[0048] Figure 19A The control sensor containing only compound 2, the control sensor containing only compound 3, the compound 2 / 3 (1 μg) bilayer sensor, and the compound 2 / 3 (3 μg) bilayer sensor are shown for 10–20 mg / m³. 3 Sensor response to sodium bicarbonate.

[0049] Figure 19B The control sensor containing only compound 2, the control sensor containing only compound 4, the compound 2 / 4 (1 μg) bilayer sensor, and the compound 2 / 4 (3 μg) bilayer sensor are shown for 10–20 mg / m³. 3 Sensor response to sodium bicarbonate.

[0050] Figure 19C The control sensor containing only compound 2, the control sensor containing only compound 5, the compound 2 / 5 (1 μg) bilayer sensor, and the compound 2 / 5 (3 μg) bilayer sensor are shown for 10–20 mg / m³. 3 Sensor response to sodium bicarbonate.

[0051] These figures are provided to illustrate various aspects of the invention and are not intended to limit the scope in terms of size, material, configuration, arrangement, or proportion, unless otherwise specified in the claims. Invention Details

[0053] While these exemplary embodiments have been described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments can be implemented, and various changes can be made to the invention without departing from its spirit and scope. Therefore, the following more detailed description of embodiments of the invention is not intended to limit the scope of the patent protection claimed by the invention, but is merely presented for illustrative purposes and is not limited to describing the features and characteristics of the invention to illustrate the best mode of operation and to sufficiently enable those skilled in the art to practice the invention. Therefore, the scope of the invention is defined only by the appended claims.

[0054] definition

[0055] In describing and claiming protection for this invention, the following terms will be used.

[0056] The singular forms “a,” “an,” and “the” include plural indicators unless the context clearly specifies otherwise. Thus, for example, referring to “a particle” includes referring to one or more such materials, and referring to “undergoing” refers to one or more such steps.

[0057] As used herein, the term “about” is used to provide for flexibility and imprecision associated with a given term, measure, or value. The degree of flexibility of a particular variable can be readily determined by those skilled in the art. However, unless otherwise stated, the term “about” generally means less than 2%, and most often less than 1%, and in some cases less than 0.01%.

[0058] As used in this document with respect to the attribute or situation being indicated, "substantially" means a degree of deviation that is small enough not to significantly diminish the attribute or situation being indicated. In some cases, the exact degree of deviation that is permissible may depend on the specific context.

[0059] As used in this article, "adjacent" refers to the proximity of two structures or elements. Specifically, elements identified as "adjacent" can be adjacent or connected. Such elements can also be close to or near each other without necessarily touching. In some cases, the exact degree of proximity can depend on the specific context.

[0060] As used herein, for convenience, multiple items, structural elements, constituent elements, and / or materials may be presented in a common list. However, these lists should be interpreted as if each member of the list were identified separately as a single and unique member. Therefore, without indication to the contrary, no single member of such a list should be construed as being equivalent in fact to any other member in the same list solely based on its presentation in the common group.

[0061] As used herein, the term “at least one of…” is intended to be synonymous with “one or more of…”. For example, “at least one of A, B and C” explicitly includes only A, only B, only C, and combinations of each.

[0062] Concentration, amount, and other numerical data may be presented in range format throughout this document. It should be understood that this range format is used merely for convenience and brevity, and should be flexibly interpreted to include not only the values ​​explicitly listed as limits of the range, but also all individual values ​​or subranges contained within that range, as if each value and subrange were explicitly listed. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly listed limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that list only one value, such as “less than about 4.5,” which should be interpreted to include all the values ​​and ranges listed above. Furthermore, this interpretation should apply regardless of the breadth of the range or the characteristics described.

[0063] Any step listed in any method or process claim may be performed in any order and is not limited to the order presented in the claims. The limitation of device plus function or step plus function will only be used where all of the following conditions are present in the limitation for a particular claim: a) it clearly states "for device" or "for step"; and b) it clearly states the corresponding function. The structure, material, or behavior supporting the device plus function is clearly stated in the description herein. Therefore, the scope of the invention should be determined only by the appended claims and their legal equivalents, and not by the description and examples given herein.

[0064] Sensor for detecting solid particles of target salt

[0065] The techniques described herein can provide low-cost, low-power, small-shape-factor sensors capable of identifying at least one chemical component in solid particles of a target salt. The sensors can utilize a solid-state ion exchange process to release one of the compounds as a free, neutral molecule, which can then be detected using a chemical sensor.

[0066] Many particles of interest (such as explosives and anesthetics) are in the form of salts, where acidic and basic components are bound together by ionic bonds. These ionic bonds can be broken by an ion exchange process involving the introduction of a base or acid. If a base is introduced, the base can remove the acidic component from the target salt, releasing the basic component of the target salt as a free base. If an acid is introduced, the acid can remove the basic component of the target salt, releasing the acidic component of the target salt as a free acid. The released component can then be detected. In some instances, the released component can be detected using a chemical sensor, mass spectrometry, or other methods. This disclosure describes an ion exchange process for dissociating components of solid particles collected in air, methods for specifically detecting target components, and applications using these methods to identify exposure to fentanyl or other ionic compounds.

[0067] In the sensors described herein, the ion exchange process can be performed using an ion exchange medium comprising a porous structured material functionalized with basic or acidic functional groups. Thus, the basic or acidic functional groups can remove the acidic or basic components of the target salt, respectively. This can convert the target salt into a free base or a free acid. The porous structured material can be a variety of materials having a structure that allows gaseous and solid particles of the target salt, which can be entrained in a gas, to enter the pores of the material. In some instances, the porous structured material may include organic nanofibers, polymer nanofibers, carbon nanotubes, silicon nanowires, metal oxide nanowires, boron nitride nanotubes, aerogels, degels, highly porous ceramics, metal-organic frameworks (MOFs), glassy carbon, chalcopyrite, chalcogenides, or combinations thereof.

[0068] In one embodiment, the ion exchange medium may comprise organic nanofibers functionalized with a base (e.g., a primary amine). When salt particles are adsorbed onto the nanofibers, acidic components (e.g., hydrochloric acid) are drawn from the particles by the strong base functionality of the nanofibers. The one-dimensional nanofiber structure of the organization provides an efficient pathway for the favorable diffusion of acids, enabling a large effective surface area to drive the ion exchange process. Furthermore, the nanofibers form a porous membrane that facilitates the transport of the released components. In some cases, the particles may be fentanyl hydrochloride, a common opioid drug that releases fentanyl as a free base due to the ion exchange process.

[0069] In another embodiment, the sensor comprises two components: a top adsorption layer and a bottom sensing layer. The top adsorption layer collects particles and releases the target component using the ion exchange process described above. The bottom sensing layer detects the released component of the salt, for example, by a change in conductivity. The sensing layer may consist of a second porous structured material that can be functionalized to detect free bases or free acids released from the adsorption layer. Any of the porous materials mentioned above can be used for the sensing layer. In a particular embodiment, the sensing layer may comprise organic nanofibers that are functionalized to detect free bases or free acids of the target salt (e.g., the free base fentanyl). The organic nanofibers may be in contact with an electrode pair to which an electrical bias is applied. The nanofibers may change their conductivity in response to the target chemical, producing a measurable change in current. Other forms of chemical sensors may be used, such as electrochemical cells, conductive polymers, fluorescent polymers, colorimetric sensors, inorganic nanostructures, nanotubes (boron nitride or carbon), graphene, two-dimensional dichalcogenides, and metal oxides.

[0070] For convenience and to enhance the sensing capabilities of the sensor, this type of dual-layer sensor can be incorporated into instruments that include various additional components. The instrument may include an interface between the environment and the sensor, as well as an interface between the sensor and the user. In some instances, the instrument may include multiple components or subsystems, such as: a housing; a sampling system (passive or active) that facilitates interaction between the sensor and the environment; the sensor itself; electronic components that operate the sensor (amplifiers, analog-to-digital converters, multiplexers, microcontrollers, passive components, etc.); a power supply (e.g., batteries, transformers, etc.); operating system firmware; a user interface (e.g., tactile alarms, visual alarms, audible alarms, displays); and communication (e.g., Wi-Fi, Bluetooth, USB, LTE, LoRa, etc.).

[0071] The instrument can have various shape factors. One example shape factor is a wearable detector. In this embodiment, a dual-layer sensor can be mounted in a wearable, battery-powered device. The wearable device can be sized for easy wearing or attachment to clothing. For example, the wearable device can have a length, width, and / or height from about 0.5 inches to about 4 inches. Particles of the target salt can be actively delivered to the sensor using a blower. The presence of the target compound can be alerted to the user using auditory, visual, and tactile alarms. An example is a wearable sensor for detecting fentanyl compounds that would be used by the first responder community. A non-limiting example of such a wearable sensor is described in U.S. Patent Application Publication 20200326286, which is incorporated herein by reference.

[0072] In another form factor, the sensor can be housed in a fixed device. This implementation can be similar to a smoke detector. The device can be mounted in a fixed location (e.g., a wall). The sensor can be exposed to the environment for passive sampling. Power can be supplied via a battery or wire. One example could be a smoke detector where the sensor is able to distinguish between smoke and vapor. A second example could be an outdoor air monitor capable of differentiating between primary (e.g., soot, dust) and secondary (typically ammonium nitrate) particulate matter.

[0073] The sensing layer can be a chemiluminescence sensing layer coated on or between electrodes. In any of the examples described herein, the sensing layer material can be electrically connected to a pair of electrodes so that current can flow from one electrode through the sensing layer to the other. The chemiluminescence sensing material can exchange electrons with the adsorbed gas, causing a change in the resistivity of the sensing material. This change in resistivity can be measured electronically to develop a fingerprint of the specific gas. As mentioned above, some target compounds, such as fentanyl, can be found in solid powder particles rather than as a gas. Fentanyl is typically in the form of fentanyl hydrochloride powder, which has a negligible vapor pressure. In fact, the saturated vapor of fentanyl is significantly below dangerous concentrations. The threat of fentanyl inhalation is due to the possibility of inhaling solid particles of fentanyl hydrochloride. Therefore, the bilayer design described herein allows solid particles of fentanyl hydrochloride to be adsorbed in the top adsorption layer, where free fentanyl can diffuse to the sensing layer, where it can be detected by changes in resistivity. Fentanyl is a weak base, and strong bases can adsorb hydrochloric acid and convert fentanyl into its more volatile free base form. Once converted to the free base form, fentanyl can be detected by the sensing layer of the sensor described herein. Fentanyl has a pKa of 8.4, however, alkylamines with primary and secondary amines have pKa values ​​greater than 10.5. The sensor can be synthesized using primary and secondary alkylamines, which readily convert and decompose the fentanyl hydrochloride into its free base form.

[0074] Although fentanyl hydrochloride is discussed as an example, a variety of other target salts can also be detected using the sensors described herein. If the target compound can be identified by the unique free base form of the salt, the sensor can include an adsorption layer functionalized with basic functional groups to remove the acidic component of the target salt and allow the free base molecules to be detected through the sensing layer. On the other hand, if the target salt can be identified by the unique free acid form, the adsorption layer can be functionalized with acidic functional groups to remove the basic component of the target salt, forming a free acid that can be detected by the sensing layer.

[0075] The dual-layer sensor described in this paper can detect target compounds at low concentrations with good response time. In experimental testing, the sensor designed for the detection of fentanyl hydrochloride was tested using a fentanyl hydrochloride simulant. The sensor was able to detect fentanyl at a concentration of 1.6 mg / m³ in less than 5 minutes. 3 Solid particles of the fentanyl hydrochloride analogue. When the same sensor is exposed to cutting agents (such as mannitol, lactose, or baking soda), even when using high concentrations such as 10-20 mg / m³, 3 No response was observed at that time. Another interfering agent, metamizole, showed a smaller response in the opposite direction to the fentanyl analogue.

[0076] These results demonstrate the feasibility of using the sensors described in this paper to detect fentanyl in its relevant forms and concentrations. Furthermore, the sensors are suitable for integration into small wearable devices. Such products can provide first responders with early warning of fentanyl exposure, accelerating diagnosis and improving the survival chances of already exposed first responders.

[0077] In more specific instances, porous structured materials, such as adsorption layers, sensing layers, or both, can be composed of organic nanofibers. In some instances, organic nanofibers can be formed by assembling modular molecules that are functionalized to alter their sensitivity and selectivity to compounds of interest. Once assembled from these modular molecules, the nanofibers can be coated onto electrode pairs so that the resistivity of the nanofiber layer can be measured as it interacts with molecules in the environment. The resistance of the nanofibers can be varied because the electron density changes as molecules adsorb onto the surface of the nanofibers and transfer electrons. Since the response is not inherently covalent, the sensor can be recovered from this interaction and can be reused. The sensor response is proportional to the Langmuir adsorption model, enabling the quantification of detected chemicals. Non-limiting examples of modular materials for forming nanofibers may include those listed in U.S. Patents 8,486,708; 8,889,420; 8,703,500 and 8,809,063, U.S. Patent Application Publications US-2014-0235493-A1; US-2018-0201612-A1 and US-2017-0160252-A1, each of which is incorporated herein by reference. These materials may be functionalized with amines, as described herein, for forming basic nanofibers in an adsorption layer; or used as a display sensing layer.

[0078] Figure 1A cross-sectional side view of an example sensor 100 according to this disclosure is shown. This example includes a supporting substrate 110, a pair of electrodes 120 formed on the supporting substrate, a sensing layer 130 formed over the supporting substrate and the electrodes, and an adsorption layer 140 formed over the sensing layer. The sensing layer is in contact with the electrodes, and the electrodes are separated by the sensing layer, meaning that the path of current from one electrode to the other passes through the sensing layer. Therefore, changes in the conductivity of the sensing layer can be measured by passing current between the electrodes. The adsorption layer may include an ion exchange medium formed of a first porous structured material. The first porous structured material may be functionalized with basic or acidic functional groups to remove acidic or basic components from a target salt to form a free base or free acid of the target salt. The sensing layer may include a second porous structured material. The second porous structured material may be functionalized to detect the free base or free acid of the target salt by changes in conductivity.

[0079] Figure 1 The specific sensor design shown is a single example. Other arrangements of the sensor's components are also possible. For example, Figure 1 A sensing layer is shown deposited on top of the electrodes and filling the space between them. However, in other instances, the sensing layer material may not be on top of the electrodes, or it may not fill the space between the electrodes. Any arrangement can be used as long as the sensing layer material is in electrical contact with both electrodes so that current flows from one electrode to the other through the sensing layer. Furthermore, in some instances, the adsorption layer may cover the entire sensing layer, while in others it may cover only a portion. In some instances, the adsorption layer may be deposited on top of the electrodes, while in others it may not. In some instances, both the adsorption layer and the sensing layer may be located between the electrodes. However, in some instances, the adsorption layer may be separated from the electrodes by the sensing layer so that the adsorption layer material is not in direct contact with the electrodes. Therefore, current can flow from one electrode to the other through the sensing layer, rather than through the adsorption layer. In another alternative, current can also flow through the adsorption layer.

[0080] Figure 2A-2D The process of manufacturing another instance sensor 200 is shown. Figure 2A A top view of a support substrate 210 and two electrodes 220 formed on the support substrate is shown. Figure 2B The sensing layer 230, composed of nanofibers 232, is shown deposited on the substrate and electrodes. Figure 2C The adsorption layer 240, composed of nanofibers 242, is shown deposited on top of the sensing layer. Figure 2DA side cross-sectional view of the sensor is shown. As explained above, the nanofibers in the adsorption layer can be functionalized with basic groups that can remove acid components from the target salt. The nanofibers in the sensing layer can detect the free basic form of the target salt by changes in conductivity.

[0081] In a specific instance, Figure 2A-2D The type of sensor shown can be used to detect fentanyl hydrochloride. An adsorption layer can capture fentanyl hydrochloride particles and convert them into a free base by adsorbing hydrochloric acid. The free fentanyl base can then diffuse to a sensing layer that can detect it. With this system, the adsorption layer can have a sufficiently high density to capture fentanyl hydrochloride particles and provide sufficient interfacial interactions to completely convert the particles into their free base form. The nanofibers of the sensing layer can then sensitively detect fentanyl in its free base form.

[0082] Figures 3A-3B Another example sensor 300 is shown. This sensor includes interdigitated electrodes 320. The electrodes can be formed as a patterned metal layer on a supporting substrate 310. For clarity, Figure 3A The substrate and electrodes without an overcoat are shown. Figure 3B A cross-sectional side view of the sensor is shown. This view shows the sensing layer 330 and adsorption layer 340 deposited on the substrate and electrodes. In this example, the electrodes include a main electrode body and fingers extending from the main electrode body towards the opposing electrode. In this example, the fingers of the electrode have a width smaller than the main electrode body. However, in other examples, the electrode body and fingers may have the same thickness so that the entire electrode has a uniform thickness. In some cases, using interdigitated electrodes can increase the sensor's sensitivity by allowing more current to pass through the sensing layer between the electrodes when target molecules diffuse into the sensing layer.

[0083] Figure 4A , 4C Figure 4E shows a schematic diagram of the process of detecting fentanyl hydrochloride using sensor 400, and the accompanying data from... Figure 4B , 4D The theoretical response of the sensor in 4F. Figure 4A In this process, fentanyl hydrochloride particles 402 are introduced into the sensor. Figure 4C In this process, fentanyl hydrochloride particles are adsorbed onto adsorption layer 440. Due to potential charge transfer between the nanofibers and particles, a small response can occur. Figure 4F In this method, alkali-functionalized nanofibers are used to convert fentanyl hydrochloride into its free base through ion exchange interactions, releasing fentanyl to migrate to the sensing layer 430. The sensing nanofibers interact with the fentanyl molecules via charge transfer, leading to an increase in signal. This approach enables the detection of airborne particles of non-volatile substances such as fentanyl.

[0084] Figure 5 Another example sensor 500 is shown, which includes a support substrate 510, a pair of electrodes 520, a sensing layer 530, and an adsorption layer 540, as in the previous example. The sensor also includes a housing 550 surrounding the substrate, electrodes, sensing layer, and adsorption layer. A blower 560 is positioned to blow air into the housing so that the air contacts the adsorption layer. This can draw in particles of target salt from the surrounding environment. The sensor also includes an alarm 570 connected to the electrodes and configured to trigger an alarm signal. The alarm signal may include a tactile alarm, a visual alarm, an audible alarm, a display, or a combination thereof.

[0085] In further details regarding the target salt, the sensor described herein can be designed to detect a variety of target salts. Target salts can include both alkaline and acidic components. In various instances, target salts can include hydrochlorides, sodium, sulfates, acetates, phosphates, diphosphates, chlorides, potassium, maleates, calcium, citrates, methanesulfonates, nitrates, tartrates, aluminum, gluconates, perchlorates, or other acidic or alkaline components. In some instances, the target salt can be a salt of an alkaloid. In more specific instances, the target salt can be a salt of an opioid preparation. In particular instances, the target salt can be fentanyl hydrochloride or carfentanil. Target salts can be in the form of solid particles. In some instances, the target salt can have an average particle size from about 0.1 μm to about 10 μm. In further instances, the average particle size can be from about 0.1 μm to about 5 μm, or from about 0.1 μm to about 1 μm, or from about 1 μm to about 5 μm, or from about 1 μm to about 10 μm. As used in this article, if the particles are non-spherical, the average particle size may refer to the number mean of the longest dimension of the particles, or if the particles are spherical, it may refer to the diameter of the particles.

[0086] The support substrate used to manufacture the sensor can include a variety of rigid materials. In some examples, the support substrate can include glass, silicon, alumina, sapphire, mica, quartz, plastic, or combinations thereof. Optionally, the support substrate can be a flexible substrate. Non-limiting examples of suitable flexible substrates include polyethylene and MYLAR. The thickness and other dimensions of the substrate are not particularly limited. In some examples, the substrate can have a thickness from about 0.1 mm to about 1 cm or from about 0.1 mm to about 2 mm.

[0087] As explained above, the sensor may comprise two layers of porous structured material. In many instances, the two layers may consist of two different porous structured materials, including a first porous structured material for the top adsorption layer and a second porous structured material for the bottom sensing layer. The first and / or second porous structured material may include organic nanofibers, polymer nanofibers, carbon nanotubes, silicon nanowires, metal oxide nanowires, boron nitride (BN) nanotubes, aerogels, degels, highly porous ceramics, metal-organic frameworks (MOFs), glassy carbon, chalcopyrite, chalcogenides, or combinations thereof. The porous structured material may also be functionalized with various functional groups. In some instances, the first porous structured material may be functionalized with basic functional groups to form a free base of the target salt when the target salt particles are adsorbed onto the first porous structured material. The second porous material may consist of acidic nanofibers capable of detecting the free base of the target salt. Some examples of basic functional groups may include primary amines, secondary amines, tertiary amines, and combinations thereof. In some instances, the basic functional group may include hexylamine, ethylethylamine, dimethylbutylamine, or combinations thereof. In some instances, the first porous structured material may include organic nanofibers containing these functional groups.

[0088] In other examples, the first porous structured material can be functionalized with acidic functional groups to form a free acid of the target salt when particles of the target salt are adsorbed onto the first porous structured material. Non-limiting examples of acidic functional groups may include carboxylic acids, phenols, thiophenols, alkyl or aromatic phosphonic acids, alkyl thiophosphates, etc. As a general guideline, organic compounds with a pKa less than 7.0 can be used as acidic functional groups.

[0089] In some instances, the first porous structured material may be composed of organic nanofibers. In some instances, the first porous structured material may comprise first organic nanofibers assembled from stacked molecules selected from: 3,4,9,10-perylene-tetracarboxylic acid diimide, 3,4,9,10-perylene-tetracarboxylic acid dianhydride, perylene 3,4,9,10-tetracarboxy-3,4-anhydride-9,10-imide, indole-carbazole derivatives, and oligomers composed of 3 to 9 carbazole derivative monomers, wherein at least a portion of the stacked molecules is further functionalized with basic functional groups. In some instances, the first organic nanofibers may be assembled from stacked molecules having one of the following structures:

[0090]

[0091]

[0092]

[0093]

[0094] The adsorption layer can have a thickness sufficient to capture particles of the target salt and allow the alkaline or acidic components of the target salt to diffuse into the sensing layer. In some examples, the adsorption layer can have a thickness from about 50 nm to about 5 μm. In other examples, the adsorption layer can have a thickness from about 50 nm to about 1 μm, or from about 50 nm to about 500 nm, or from about 1 μm to about 5 μm. In a further example, the adsorption layer can have a thickness of approximately 3 mm. 2 The mass per area ranges from approximately 0.1 μg to 6 μg. In some examples, the area of ​​the adsorbed layer can range from approximately 0.1 mm². 2 Up to 10mm 2 or from approximately 0.1 mm 2 Up to 1mm 2 or from about 1mm 2 Up to 10mm 2 In some instances, the adsorption layer may also have a pore size ranging from about 10 nm to about 1 μm, or from about 10 nm to about 500 nm, or from about 10 nm to about 100 nm.

[0095] In a further example, the sensing layer may be composed of a second porous structured material. In some examples, the second porous structured material may comprise a second organic nanofiber assembled from stacked molecules selected from: substituted or unsubstituted 3,4,9,10-perylene-tetracarboxylic acid diimide, substituted or unsubstituted 3,4,9,10-perylene-tetracarboxylic acid dianhydride, substituted or unsubstituted perylene 3,4,9,10-tetracarboxy-3,4-anhydride-9,10-imide, indole-carbazole derivatives, and oligomers composed of 3-9 carbazole derivative monomers. In a further example, the second porous structured material may comprise a second organic nanofiber assembled from stacked molecules having one of the following structures:

[0096]

[0097]

[0098] In some instances, the sensing layer may have a thickness from about 50 nm to about μm, or from about 50 nm to about 1 μm, or from about 1 μm to about 5 μm. In further instances, the sensing layer may have a thickness of approximately 3 mm. 2 The mass per area is approximately 0.1 μg to approximately 6 μg.

[0099] The electrodes of the sensor can be formed by depositing a conductive material onto a substrate to create two electrodes separated by a gap. As explained above, the gap can be bridged by a sensing layer so that current can be transferred from one electrode to the other through the sensing layer. In some examples, the electrodes can be composed of gold, titanium, indium tin oxide, indium zinc oxide, tungsten, aluminum, platinum, silver, copper, PEDOT:PSS, or combinations thereof. There is no particular limitation on the thickness of the electrode material. In some examples, the electrode material can be deposited with a thickness from about 5 nm to about 100 μm. In further examples, the electrodes can be separated by a gap distance from about 50 nm to about 100 μm. Example

[0100] Three novel molecules for adsorption layer nanofibers in bilayer sensors were synthesized, and their structures were confirmed using nuclear magnetic resonance spectroscopy. The nanofibers were grown by injecting a concentrated solution of the molecules into a non-solvent. The non-solvent caused molecular precipitation. Due to the planar π-conjugated structure of the molecules, growth was predominantly unidirectional, leading to nanofiber formation. Once the correct assembly conditions were determined, each nanofiber was coated onto an electrode and characterized using scanning electron microscopy (SEM) imaging and electrical characterization.

[0101] The fabrication of a dual-layer sensor can be accomplished using any suitable technique. For example, a suspension of nanofibers can be coated onto the electrodes to form each layer. The coating may be sufficient to provide complete coverage (i.e., filling the gaps between the electrodes and completely covering the underlying coating while achieving the target thickness). Excessive thickness can increase response time and decrease sensitivity due to increased diffusion time, depending on the nanofiber network density and porosity of the material used.

[0102] Fentanyl detection can be performed using sensors that respond to fentanyl hydrochloride particles in the environment. The Blaumstein Atomizer (BLAM) uses a solution to generate aerosol particles with a diameter between 0.7 and 2.5 μm, a size relevant to inhalation. Once nebulized, the mist is fed into a solvent-removed diffusion dryer, producing dried particles at the outlet. The concentration is controlled by varying the injection rate of the BLAM or by diluting the sample air.

[0103] Particles were generated using a fentanyl simulant in solution. Prior to testing, Dusttrak from TSI Incorporated (USA) was used. TM The particle counter II quantifies the hydrochloric acid particles of the simulant generated by the particle generator. Three different concentrations were tested to demonstrate the existence of a dose-dependent response. The concentrations were: 1–2, 2–4, and 8–16 mg / m³. 3 .

[0104] Fentanyl is typically found in the presence of a cutting agent, which can potentially interfere with the sensor. The potential cross-reactivity of several interfering substances was tested using the same test fixture described above. The concentrations of aminopyrine, mannitol, lactose, and baking soda were tested at 10x higher concentrations than those used for the fentanyl simulant.

[0105] Each newly synthesized adsorption layer nanofiber possesses a unique morphology and exhibits a variety of properties. The molecular structure and SEM images of each new adsorption layer are included in... Figures 6A-6D In this context, surface area, porosity, and the activity of functional groups are all factors to consider when selecting nanofibers for specific target compounds. Variations in each can increase or decrease the sensitivity and selectivity of binding, and can be tailored to specific targets. Figure 6A The image shows bis(N-hexylamine) nanofibers. Figure 6B Bis(N-ethylethylamine) nanofibers were demonstrated. Figure 6C Bis(N-propylpropylamine) nanofibers were shown. Figure 6D Bis(dimethylbutylamine) nanofibers were demonstrated and possessed [the following properties / functions]: Figure 6A and 6B The morphology between nanofibers is shown in the image. Figure 7A An example of a sensing layer coated on an electrode is shown, and used as a control. Figure 7B The sensing layer is shown after undergoing a second coating process using ethanol without any nanofibers.

[0106] A bilayer sensor was then fabricated using nanofibers for both the sensing and adsorption layers, with each layer using a standard 6 μg nanofiber material. Before fabrication, the sensing and adsorption layers exhibited current measurements of 1.1 nA and 130 μA, respectively. After fabrication, the sensor current increased by two orders of magnitude, reaching 180 nA. This increase appears to be caused by the nanofiber doping of the sensing layer in the adsorption layer, which subsequently increased the electron density of the sensing layer and the overall conductivity of the bilayer sensor. Optionally, the adsorption layer could carry most of the current because it is more conductive. The latter is less likely, as charge is difficult to move perpendicular to the plane of the electrodes. Significant doping of the sensing layer reduces the bilayer's sensitivity to fentanyl, thus reducing the amount of adsorption layer material could decrease the variation in sensor current. A thinner adsorption layer film could also facilitate the transfer of free fentanyl base to the sensing layer, a process expected to be diffusion-limited.

[0107] A uniform bilayer was created using 1 and 3 μg of bis-N,N-dimethylbutylamine adsorption layer nanofibers and all three sensing layers; SEM images of the bilayer sensor are included in... Figures 8A-8D In. Figure 8CThe sensing layer is clearly visible at the top of the image shown in the 1 μg bilayer sample. The sensing layer nanofibers can be seen through the pores of the adsorption layer at several other points in this image. (Distinguishing the sensing layer in the 3 μg sample as a control) Figure 8D (As shown) it is more difficult, but it can be seen in the corner of the image, indicating that its thickness is insufficient to completely cover the sensing layer. Both masses of the adsorption layer material form a uniform film, and the underlying sensing layer is still exposed.

[0108] Use 1( Figure 9A ) and 3μg ( Figure 9B The sample with the adsorption layer material coated on the sensing layer (compound 1) was also made of dibutylamine nanofibers, and the results included Figure 9A and 9B middle. Figure 9C The sensing layer before the adsorption layer was applied is shown. A 1 μg sample completely covered the sensing layer, but a small amount of the underlying sensing layer was visible. After increasing the adsorption layer to 3 μg of nanofiber material, the sensing layer was completely covered by the adsorption layer. However, complete coverage may not be a problem as long as the adsorption layer is not too thick, because the porosity of the adsorption layer can still allow for efficient diffusion of the fentanyl free base.

[0109] Figure 10A and 10B The text shows that 1 ( Figure 10A ) and 3μg ( Figure 10B A bilayer sample with a loading of bis(N-ethylethylamine) nanofibers coated onto the sensing layer. The lower sensing layer is identified by a red oval. Figure 10C The entire sensing layer is shown before the application of the adsorption layer. Due to the large diameter of the bis(N-ethylethylamine) nanofibers, fentanyl particles will have less surface area for adsorption, but the pathway for fentanyl migration to the sensing layer may be more efficient. No easily identifiable sensing layer was visible in the 3 μg adsorption layer bilayer sample, but the porosity of the bis(N-ethylethylamine) nanofibers is expected to promote diffusion. The sensing layer may not be observable due to the depth of the SEM field. Because the packing density of this material is lower than other materials, a thicker film is expected for the same mass of nanofibers.

[0110] Figure 11 The molecular structure and internal names of the sensing and adsorption layer nanofibers selected for testing are shown.

[0111] Fentanyl analogues were selected because they are expected to elicit a similar response to fentanyl. For safety and licensing reasons, initial testing required analogues. Four different candidates were identified, which have structures similar to fentanyl, such as... Figure 12 As shown. The candidate fentanyl analogue is: norfentanyl HCl (…). Figure 122) Acrylamide-2-methyl-N-[1-(phenylmethyl)-4-piperidinyl] Figure 12 3) Acrylamide-N-[1[2-(4-hydroxyphenyl)methyl]-4-piperidinyl]-N-phenyl ( Figure 12 4) and benzylfentanyl ( Figure 12 5). Ultimately, I chose... Figure 12 Compound 3 in the compound, because Figure 12 4 in the sample contains phenolic groups that can be detected by nanofibers, and 2 has been shown to be a controlled substance.

[0112] Fentanyl analogues at three different concentrations (1-2, 2-4 and 8-16 mg / m³) 3 The test was conducted using three different interfering agents (i.e., D-mannitol, aminopyrine, and α-D-lactose).

[0113] Figures 13A-13C The sensor responses for the various experiments performed are shown. The experiments began with the injection of pure solvent. The first black arrow (left) indicates the baseline zero point and corresponds to the time it took to open the valve and activate the sample injector for target analyte delivery. Because it takes time for the sample to reach the nebulizer, the gray box indicates the expected duration for the nanofibers to receive analyte particles based on the injection pump flow rate. Finally, the second black arrow (right) indicates the time it took to close the sample injection pump and activate the valve to stop the flow of analyte solution to the nebulizer.

[0114] The sensing results of the combination of the compound 2 sensing layer and the compound 4 adsorption layer at each simulant concentration include Figures 13A-13C The first observation that can be drawn is that the compound 4 adsorption layer control has a dose-dependent response, which is in Figure 13B and 13C This is more pronounced at medium concentrations. At the minimum concentration, there appears to be almost no response. Figure 13A Compared to the other adsorption layer functional groups, the amine functional group at the end of the alkyl chain of compound 4 has the greatest potential response to free base molecules because it has the greatest ability to drive ion exchange interactions with fentanyl hydrochloride particles, and also responds to free base fentanyl.

[0115] The 2 / 4 bilayer pair of compounds also exhibited a dose-dependent response that increased with increasing concentration. In this case, in Figure 13C The intermediate bilayer clearly performed better than the control. The bilayer pair of compound 4 appeared to have the best separation compared to the control of compound 2 at the highest concentration. Figure 13C However, at the two lower concentrations ( Figure 13A and Figure 13B There is a lack of significant separation.

[0116] Figure 14AThe sensor response of the sensor formed by the compound 2 / 3 bilayer pair is shown; Figure 14B The sensor response of compound 2 / 4 bilayer pair was shown; and Figure 14C The sensor response of the compound 2 / 5 bilayer pair is shown.

[0117] Four potential interfering agents (D-mannitol, sodium bicarbonate, aminopyrine, and α-D-lactose) at 10-20 mg / m³ 3 The tests were conducted at concentrations approximately 10 times higher than the lowest concentrations tested for fentanyl analogues. These interfering substances were tested because they are common cleavage agents encountered in the real-world distribution of this opioid in fentanyl-based formulations. The molecular structures of all four are included... Figure 15 middle.

[0118] At 10-20 mg / m 3 The results of the adsorption of aminopyrine on each adsorbed layer and compound 2 pairs are included in Figures 16A-16C A decreased response was observed, which may be due to the sulfonic acid pair in the chemical structure of metamizole, which is quite different from the increased response of fentanyl mimics. Figure 16A Compound 2 / 3 bilayer pairs and controls were shown, all of which showed slight responses; the 3 μg bilayer sample had a greater response than the 1 μg bilayer sample.

[0119] Figure 16B The bilayer of compounds 2 / 4 also responded to metamizole, while the sensing and adsorption layer controls showed negligible responses. The dose-dependent response of the compound 4 control to fentanyl mimics and its lack of response to metamizole may produce selectivity for fentanyl mimics while reducing false positives due to metamizole.

[0120] Figure 16C The compound 2 / 5 bilayer pair shown exhibits only a small response to aminopyrine compared to other bilayer pairs on the sensor card. These results demonstrate that the adsorption layer plays a crucial role in the sensor response. In this case, adsorption layers with more readily accessible amines tend to produce a larger response to the simulant. In some cases, thicker films also cause a larger response to interfering substances than thinner films. The accessibility of the amine and the amount available can determine the rate at which the ion exchange process occurs, thus controlling the sensor response. Further tuning of the sensing layer can improve the selectivity of the sensor.

[0121] Finally, the compound 2 sensing layer control also exhibited a negligible response to aminopyrine. This could be another good nanofiber that contributes to selectivity. These results demonstrate the influence of the adsorption layer on selectivity. Further optimization of the adsorption layer has the potential to improve selectivity. The use of a sensor array eliminates the possibility of the response to aminopyrine interfering with fentanyl detection. For example, a common problem is that the responses to fentanyl and aminopyrine can cancel each other out, resulting in a zero response. While there is indeed a ratio of fentanyl to aminopyrine that produces a canceling effect for one sensor, this ratio will be different for other sensors in the array. Selectivity for aminopyrine can be obtained through signal processing.

[0122] Figures 17A-17C The figure shows adsorption and 10-20 mg / m³ for each pair in the bilayer. 3 The sensor response of D-mannitol. D-mannitol does not contain functional groups that typically interact with these sensors. Figures 17A-17C The response of each of the bilayer pairs appears to be drifting and no significant response to the analyte has been demonstrated. D-mannitol is unlikely to be a contaminant for the sensor.

[0123] The sensor is effective for 10-20 mg / m³ 3 The results of the response to α-D-lactose have been included in Figures 18A-18C The α-D-lactose molecule has a functional group similar to D-mannitol and did not elicit a response from the nanofibers. This is also unlikely to be a contaminant. These tests demonstrate the selectivity of the bilayer sensor for fentanyl and indicate that fentanyl will be detectable in the presence of these compounds.

[0124] Finally, the last interfering substance tested was sodium bicarbonate (baking soda), which includes... Figures 19A-19C In the middle. Because it lacks reaction sites with nanofibers, Figures 19A-19C The bilayer and control showed no response to sodium bicarbonate and are not expected to mask fentanyl in real-world environments. Testing in a mixture would require additional particle generator, method development, and testing time.

[0125] These sensors are the only chemiluminescence technology to offer highly intrinsically selective analytes. Because nanofibers are self-assembled from organic molecules, they are tailored to respond to specific analytes or classes of analytes before fabrication. Furthermore, the large surface area and high porosity of nanofiber membranes result in rapid absorption and desorption rates, leading to detection limits for some chemicals down to parts-per-trillion. Finally, nanofibers operate at room temperature and atmospheric pressure, eliminating power consumption compared to technologies requiring additional heating or vacuum. Nanofibers also offer improvements over various shortcomings of optical technologies, particularly low detection limits and chemical specificity. Compared to laboratory instruments, organic nanofibers can be implemented at low cost and with a portable form factor without significant loss of sensitivity or selectivity.

[0126] List of additional embodiments

[0127] The following list describes specific embodiments of the techniques described herein. For convenience, these specific embodiments are numbered. Examples 1-28 are sensors according to the techniques described herein. Examples 29-58 are methods for detecting solid particles of a target salt.

[0128] Example 1: A sensor for detecting solid particles of a target salt, comprising: a supporting substrate; an adsorption layer comprising an ion exchange medium formed of a first porous structured material functionalized with basic or acidic functional groups, wherein the basic or acidic functional groups remove acid or basic components from the target salt to form a free base or free acid of the target salt; a sensing layer oriented between the supporting substrate and the adsorption layer, the sensing layer comprising a second porous structured material functionalized to detect the free base or free acid of the target salt by a change in conductivity; and an electrode pair contacting and separated from the sensing layer.

[0129] Example 2: A sensor of any one of Examples 1-28, wherein the target salt is a salt of an alkaloid.

[0130] Example 3: A sensor of any one of Examples 1-28, wherein the target salt is a salt of an opium preparation.

[0131] Example 4: A sensor of any one of Examples 1-28, wherein the target salt is fentanyl hydrochloride or carfentanil.

[0132] Example 5: A sensor of any one of Examples 1-28, wherein the solid particles of the target salt have a particle size from about 0.1 μm to about 10 μm.

[0133] Example 6: A sensor according to any one of Examples 1-28, wherein the supporting substrate includes at least one of glass, silicon, alumina, sapphire, mica, quartz or plastic.

[0134] Example 7: A sensor according to any one of Examples 1-28, wherein the first porous structured material is functionalized with basic functional groups to form a free base of the target salt, and the second porous structured material is an acidic nanofiber functionalized to detect the free base.

[0135] Example 8: A sensor of any one of Examples 1-28, wherein the basic functional group includes primary amino, secondary amino, or a combination thereof.

[0136] Example 9: A sensor according to any one of Examples 1-28, wherein the basic functional group includes hexylamine, ethyl ethylamine, dimethyl butylamine or a combination thereof.

[0137] Example 10: A sensor according to any one of Examples 1-28, wherein the first porous structured material and the second porous structured material are formed from at least one of organic nanofibers, polymer nanofibers, carbon nanotubes, silicon nanowires, metal oxide nanowires, boron nitride nanotubes, aerogels, degels, highly porous ceramics and metal-organic frameworks (MOFs).

[0138] Example 11: A sensor of any one of Examples 1-28, wherein the first porous structured material is a network of first organic nanofibers.

[0139] Example 12: The sensor of Example 11, wherein the first organic nanofiber is assembled from stacked molecules selected from: 3,4,9,10-perylene-tetracarboxylic acid diimide, 3,4,9,10-perylene-tetracarboxylic acid dianhydride, perylene 3,4,9,10-tetracarboxy-3,4-anhydride-9,10-imide, indole-carbazole derivatives, and oligomers composed of 3 to 9 carbazole derivative monomers, wherein at least a portion of the stacked molecules is further functionalized with basic functional groups.

[0140] Example 13: The sensor of Example 11, wherein the first organic nanofiber is assembled from stacked molecules having one of the following structures:

[0141]

[0142]

[0143]

[0144]

[0145] Example 14: The sensor of Example 13, wherein the second organic nanofiber is assembled from stacked molecules having one of the following structures:

[0146]

[0147] Example 15: The sensor of Example 14, wherein the structures of the first organic nanofiber and the second organic nanofiber are X and XIV; XI and XIV; or XII and XIV, respectively.

[0148] Example 16: A sensor of any one of Examples 1-28, wherein the adsorption layer has a thickness from 50 nm to 5 μm.

[0149] Example 17: A sensor according to any one of Examples 1-28, wherein the adsorption layer has a density of 3 mm per 100 mm. 2 Mass from 0.1 μg to 6 μg, and 0.1 mm 2 Up to 10mm 2 The area.

[0150] Example 18: A sensor of any one of Examples 1-28, wherein the adsorption layer is porous with an average pore size from 10 nm to 1 μm.

[0151] Example 19: A sensor of any one of Examples 1-28, wherein the second porous structured material comprises a second organic nanofiber assembled from stacked molecules selected from: substituted or unsubstituted 3,4,9,10-perylene-tetracarboxylic acid diimide, substituted or unsubstituted 3,4,9,10-perylene-tetracarboxylic acid dianhydride, substituted or unsubstituted perylene 3,4,9,10-tetracarboxy-3,4-anhydride-9,10-imide, indole-carbazole derivatives, and oligomers composed of 3-9 carbazole derivative monomers.

[0152] Example 20: A sensor according to any one of Examples 1-28, wherein the second porous structured material comprises a second organic nanofiber assembled from stacked molecules having one of the following structures:

[0153]

[0154] Example 21: A sensor according to any one of Examples 1-28, wherein the adsorption layer and the sensing layer are in direct contact.

[0155] Example 22: A sensor of any one of Examples 1-28, wherein the sensing layer has a thickness from 50 nm to 5 μm.

[0156] Example 23: A sensor according to any one of Examples 1-28, wherein the sensing layer has a depth per 3 mm 2 Mass from 0.1 μg to 6 μg.

[0157] Example 24: A sensor of any one of Examples 1-28, wherein the electrode pair comprises gold, titanium, indium tin oxide, indium zinc oxide, tungsten, aluminum, platinum, silver, copper, PEDOT:PSS or a combination thereof.

[0158] Example 25: A sensor of any one of Examples 1-28, wherein the electrode pairs are separated by a gap distance from 50 nm to 100 μm, the interdigital gap width is from 5 μm to 50 cm, and the finger width is from 0.1 to 50 μm.

[0159] Example 26: A sensor of any one of Examples 1-28, further comprising a housing surrounding the adsorption layer, the sensing layer, and the electrode pair.

[0160] Example 27: The sensor of any one of Examples 1-28 further includes an alarm electrically connected to electrodes and adapted to trigger an alarm signal, said alarm including a tactile alarm, a visual alarm, an auditory alarm, a display, or a combination thereof.

[0161] Example 28: The sensor of any one of Examples 1-28 further includes a blower oriented to blow air into the adsorption layer.

[0162] Example 29: A method for detecting solid particles of a target salt, comprising: exposing an adsorption layer to a gaseous medium in which particles of the target salt are entrained, wherein the adsorption layer comprises an ion exchange medium formed of a first porous structured material functionalized with basic or acidic functional groups, wherein the basic or acidic functional groups remove acid or base components from the target salt to form a free base or free acid of the target salt, wherein the free base or free acid of the target salt diffuses to a sensing layer adjacent to the adsorption layer, the sensing layer comprising a second porous structured material functionalized to detect the free base or free acid of the target salt, wherein the free base or free acid of the target salt alters the conductivity of the second porous structured material; and measuring the change in conductivity of the sensing layer using an electrode pair in contact with and separated by the sensing layer.

[0163] Example 30: The method of any one of Examples 29-58, wherein the gaseous medium includes air.

[0164] Example 31: The method of any one of Examples 29-58, wherein the free alkali is a condensate, vapor or gas.

[0165] Example 32: The method of any one of Examples 29-58, wherein the concentration of the target salt in the gaseous medium is from 0.1 mg / m³. 3 Up to 100 mg / m 3 .

[0166] Example 33: The method of any one of Examples 29-58, wherein the target salt is a salt of an alkaloid.

[0167] Example 34: The method of any one of Examples 29-58, wherein the target salt is a salt of an opium preparation.

[0168] Example 35: The method of any one of Examples 29-58, wherein the target salt is fentanyl hydrochloride or carfentanil.

[0169] Example 36: The method of any one of Examples 29-58, wherein the solid particles of the target salt have a particle size from about 0.1 μm to about 10 μm.

[0170] Example 37: The method of any one of Examples 29-58, wherein the first porous structured material is functionalized with basic functional groups to form a free base of the target salt, and the second porous structured material is an acidic nanofiber functionalized to detect the free base.

[0171] Example 38: The method of any one of Examples 29-58, wherein the first porous structured material and the second porous structured material are formed from at least one of organic nanofibers, polymer nanofibers, carbon nanotubes, silicon nanowires, metal oxide nanowires, BN nanotubes, aerogels, degels, highly porous ceramics, metal-organic frameworks (MOFs), glassy carbon, chalcopyrite, and chalcogenides.

[0172] Example 39: The method of any one of Examples 29-58, wherein the first porous structured material is a network of first organic nanofibers, and the second porous structured material is a network of second organic nanofibers.

[0173] Example 40: The method of Example 39, wherein the first organic nanofiber is assembled from stacked molecules selected from: 3,4,9,10-perylene-tetracarboxylic acid diimide, 3,4,9,10-perylene-tetracarboxylic acid dianhydride, perylene 3,4,9,10-tetracarboxy-3,4-anhydride-9,10-imide, indole-carbazole derivatives, and oligomers composed of 3 to 9 carbazole derivative monomers, wherein at least a portion of the stacked molecules is further functionalized with basic functional groups.

[0174] Example 41: The method of any one of Examples 29-58, wherein the basic functional group includes primary amino, secondary amino, or a combination thereof.

[0175] Example 42: The method of any one of Examples 29-58, wherein the basic functional group includes hexylamine, ethylethylamine, dimethylbutylamine or a combination thereof.

[0176] Example 43: The method of any one of Examples 29-58, wherein the first organic nanofiber is assembled from stacked molecules having one of the following structures:

[0177]

[0178]

[0179]

[0180] Example 44: The method of Example 39, wherein the second organic nanofiber is assembled from stacked molecules having one of the following structures:

[0181]

[0182] Example 45: The method of Example 44, wherein the structures of the first organic nanofiber and the second organic nanofiber are X and XIV; XI and XIV; or XII and XIV, respectively.

[0183] Example 46: The method of any one of Examples 29-58, wherein the adsorption layer has a thickness from 50 nm to 5 μm.

[0184] Example 47: The method of any one of Examples 29-58, wherein the adsorption layer has a density of 3 mm per 100 mm. 2 Mass from 0.1 μg to 6 μg.

[0185] Example 48: The method of any one of Examples 29-58, wherein the adsorption layer is porous with an average pore size from 10 nm to 1 μm.

[0186] Example 49: The method of Example 39, wherein the second organic nanofiber is assembled from stacked molecules selected from: substituted or unsubstituted 3,4,9,10-perylene-tetracarboxylic acid diimide, substituted or unsubstituted 3,4,9,10-perylene-tetracarboxylic acid dianhydride, substituted or unsubstituted perylene 3,4,9,10-tetracarboxy-3,4-anhydride-9,10-imide, indole-carbazole derivatives, and oligomers composed of 3-9 carbazole derivative monomers.

[0187] Example 50: The method of Example 39, wherein the second organic nanofiber is assembled from stacked molecules having one of the following structures:

[0188]

[0189] Example 51: The method of any one of Examples 29-58, wherein the sensing layer has a thickness from 50 nm to 5 μm.

[0190] Example 52: The method of any one of Examples 29-58, wherein the sensing layer has a per 3mm 2 Mass from 0.1 μg to 6 μg.

[0191] Example 53: The method of any one of Examples 29-58, wherein the adsorption layer and the sensing layer are in direct contact.

[0192] Example 54: The method of any one of Examples 29-58, wherein the electrode pair comprises gold, titanium, indium tin oxide, indium zinc oxide, tungsten, aluminum, platinum, silver, copper, PEDOT:PSS or a combination thereof.

[0193] Example 55: The method of any one of Examples 29-58, wherein the electrode pairs are separated by a gap distance from 50 nm to 100 μm.

[0194] Example 56: The method of any one of Examples 29-58, wherein the free base of the target salt increases the conductivity of the second organic nanofibers in the sensing layer.

[0195] Example 57: The method of any one of Examples 29-58 further includes using a tactile alarm, a visual alarm, an auditory alarm, a display, or a combination thereof to alert a user that a target salt has been detected.

[0196] Example 58: The method of any one of Examples 29-58 further includes using a blower to blow a gaseous medium into the adsorption layer.

[0197] The foregoing detailed description has described the invention with reference to specific exemplary embodiments. However, it should be understood that various modifications and changes can be made without departing from the scope of the invention as set forth in the appended claims. The detailed description and drawings should be considered merely illustrative and not restrictive, and all such modifications or changes (if any) are intended to fall within the scope of the invention described and set forth herein.

Claims

1. A sensor for detecting solid particles of a target salt, comprising: Supporting base; An adsorption layer comprising an ion exchange medium formed of a first porous structured material functionalized with basic functional groups, wherein the basic functional groups remove acid components from the target salt to form a free base of the target salt, wherein the first porous structured material is a network of first organic nanofibers, wherein the first organic nanofibers are assembled from stacked molecules having at least one of the following structures: A sensing layer, oriented between the supporting substrate and the adsorption layer, the sensing layer comprising a second porous structured material, functionalized to detect the free alkali of the target salt by means of changes in conductivity; and Electrode pairs that are in contact with and separated from the sensing layer by the sensing layer.

2. The sensor according to claim 1, wherein the target salt is an alkaloid or a salt of an opium preparation.

3. The sensor according to claim 1, wherein the target salt is fentanyl hydrochloride or carfentanil.

4. The sensor according to claim 1, wherein the supporting substrate comprises glass, silicon, alumina, sapphire, mica, quartz, plastic or a combination thereof.

5. The sensor according to claim 1, wherein the first porous structured material is functionalized with basic functional groups to form a free base of the target salt, and the second porous structured material is an acidic nanofiber functionalized to detect the free base.

6. The sensor according to claim 1, wherein the second porous structured material comprises organic nanofibers, polymer nanofibers, carbon nanotubes, silicon nanowires, boron nitride nanotubes, aerogels, degels, highly porous ceramics, glassy carbon, chalcopyrite, chalcogenides, or combinations thereof.

7. The sensor according to claim 1, wherein the second porous structured material is a network of second organic nanofibers.

8. The sensor according to claim 7, wherein the second organic nanofiber is assembled from stacked molecules having at least one of the following structures: (XIII) (XIV)。 9. The sensor according to claim 8, wherein the structures of the first organic nanofiber and the second organic nanofiber are respectively: X and XIV; XI and XIV; or XII and XIV.

10. The sensor of claim 1, wherein the second porous structured material comprises a second organic nanofiber assembled from stacked molecules, the stacked molecules being selected from: substituted or unsubstituted 3,4,9,10-perylene-tetracarboxylic acid diimide, substituted or unsubstituted 3,4,9,10-perylene-tetracarboxylic acid dianhydride, substituted or unsubstituted perylene 3,4,9,10-tetracarboxy-3,4-anhydride-9,10-imide, indolocarbazole derivatives, and oligomers composed of 3 to 9 carbazole derivative monomers.

11. The sensor according to claim 1, wherein the adsorption layer and the sensing layer each have a thickness from 50 nm to 5 μm.

12. The sensor according to claim 1, wherein the adsorption layer and the sensing layer each have a spacing of 3 mm. 2 Mass from 0.1 μg to 6 μg, and 0.1 mm 2 Up to 10mm 2 The area.

13. The sensor according to claim 1, wherein the adsorption layer is porous with an average pore size from 10 nm to 1 μm.

14. The sensor according to claim 1, wherein the adsorption layer is in direct contact with the sensing layer.

15. The sensor of claim 1, wherein the electrode pairs are separated by a gap distance ranging from 50 nm to 100 μm.

16. A method for detecting solid particles of a target salt, comprising: An adsorption layer is exposed to a gaseous medium in which particles of the target salt are entrained. The adsorption layer comprises an ion exchange medium formed of a first porous structured material functionalized with basic functional groups, wherein the basic functional groups remove acid components from the target salt to form a free base of the target salt. The free base of the target salt diffuses into a sensing layer adjacent to the adsorption layer. The sensing layer comprises a second porous structured material functionalized to detect the free base of the target salt, wherein the free base of the target salt alters the conductivity of the second porous structured material. The first porous structured material is a network of first organic nanofibers, wherein the first organic nanofibers are assembled from stacked molecules having at least one of the following structures: and The change in the conductivity of the sensing layer is measured using an electrode pair that is in contact with and separated from the sensing layer.

17. The method of claim 16, wherein the gaseous medium comprises air.

18. The method of claim 16, wherein the concentration of the target salt in the gaseous medium is from 0.1 mg / m³. 3 Up to 100 mg / m 3 Furthermore, the solid particles of the target salt have a particle size ranging from 0.1 μm to 10 μm.

19. The method of claim 16, wherein the target salt is fentanyl hydrochloride or carfentanil.

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