Alex Nemiroski

Real-time detection of gastrointestinal bleeding remains a major challenge because there does not yet exist a minimally invasive technology that can both i) monitor for blood from an active hemorrhage and ii) uniquely distinguish it from blood left over from an inactive hemorrhage. Such a device would be an important tool for clinical triage. One promising solution, which we have proposed previously, is to inject a fluorescent dye into the blood stream and to use it as a distinctive marker of… Show more

Real-time detection of gastrointestinal bleeding remains a major challenge because there does not yet exist a minimally invasive technology that can both i) monitor for blood from an active hemorrhage and ii) uniquely distinguish it from blood left over from an inactive hemorrhage. Such a device would be an important tool for clinical triage. One promising solution, which we have proposed previously, is to inject a fluorescent dye into the blood stream and to use it as a distinctive marker of active bleeding by monitoring leakage into the gastrointestinal tract with a wireless fluorometer. This paper reports, for the first time to our knowledge, the development of a swallowable, wireless capsule with a built-in fluorometer capable of detecting fluorescein in blood, and intended for monitoring gastrointestinal bleeding in the stomach. The embedded, compact fluorometer uses pinholes to define a microliter sensing volume and to eliminate bulky optical components. The proof-of-concept capsule integrates optics, low-noise analog sensing electronics, a microcontroller, battery, and low power Zigbee radio, all into a cylindrical package measuring 11 mm × 27 mm and weighing 10 g. Bench-top experiments demonstrate wireless fluorometry with a limit-of-detection of 20 nM aqueous fluorescein. This device represents a major step towards a technology that would enable simple, rapid detection of active gastrointestinal bleeding, a capability that would save precious time and resources and, ultimately, reduce complications in patients.
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This paper demonstrates that, for applications in resource-limited environments, expensive microplate spectrophotometers that are used in many central laboratories for parallel measurement of absorbance of samples can be replaced by photometers based on inexpensive and ubiquitous, consumer electronic devices (e.g., scanners and cell-phone cameras). Two devices, (i) a flatbed scanner operating in transmittance mode and (ii) a camera-based photometer (constructed from a cell phone camera, a… Show more

This paper demonstrates that, for applications in resource-limited environments, expensive microplate spectrophotometers that are used in many central laboratories for parallel measurement of absorbance of samples can be replaced by photometers based on inexpensive and ubiquitous, consumer electronic devices (e.g., scanners and cell-phone cameras). Two devices, (i) a flatbed scanner operating in transmittance mode and (ii) a camera-based photometer (constructed from a cell phone camera, a planar light source, and a cardboard box), demonstrate the concept. These devices illuminate samples in microtiter plates from one side and use the RGB-based imaging sensors of the scanner/camera to measure the light transmitted to the other side. The broadband absorbance of samples (RGB-resolved absorbance) can be calculated using the RGB color values of only three pixels per microwell. Rigorous theoretical analysis establishes a well-defined relationship between the absorbance spectrum of a sample and its corresponding RGB-resolved absorbance. The linearity and precision of measurements performed with these low-cost photometers on different dyes, which absorb across the range of the visible spectrum, and chromogenic products of assays (e.g., enzymatic, ELISA) demonstrate that these low-cost photometers can be used reliably in a broad range of chemical and biochemical analyses. The ability to perform accurate measurements of absorbance on liquid samples, in parallel and at low cost, would enable testing, typically reserved for well-equipped clinics and laboratories, to be performed in circumstances where resources and expertise are limited.
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We use self-assembed, colloidal crystals a universal shadow-mask that changes its pattern based on the angle at which you deposit material. We discovered that by depositing multiple materials at different angles to an array of spheres, you can fabricate very sophisticated arrays of nanoantennas that would be very difficult to produce using conventional means (which would require a new stencil to be registered for each new material). By eliminating the need to produce and register multiple… Show more

We use self-assembed, colloidal crystals a universal shadow-mask that changes its pattern based on the angle at which you deposit material. We discovered that by depositing multiple materials at different angles to an array of spheres, you can fabricate very sophisticated arrays of nanoantennas that would be very difficult to produce using conventional means (which would require a new stencil to be registered for each new material). By eliminating the need to produce and register multiple stencils, we can rapidly prototype a new design in just several hours. Show less

We describe several noncontact methods of orienting objects in three-dimensional (3D) space using Magnetic Levitation (MagLev), and report the discovery of a sharp geometry-dependent transition of the orientation of levitating objects. An analytical theory of the orientation of arbitrary objects in MagLev explains this transition. MagLev is capable of manipulating and orienting hard and soft objects, and objects of irregular shape. Because controlling the orientation of objects in space is a… Show more

We describe several noncontact methods of orienting objects in three-dimensional (3D) space using Magnetic Levitation (MagLev), and report the discovery of a sharp geometry-dependent transition of the orientation of levitating objects. An analytical theory of the orientation of arbitrary objects in MagLev explains this transition. MagLev is capable of manipulating and orienting hard and soft objects, and objects of irregular shape. Because controlling the orientation of objects in space is a prerequisite for assembling complex structures from simpler components, this paper extends MagLev into 3D self-assembly, robotic assembly, and noncontact (stiction-free) orientation of hard and soft objects for applications in biomimetics, soft robotics, and stimulus-responsive materials, among others. Show less

The ability to perform electrochemical testing in the field, and in resource-limited environments, and to transmit data automatically to “the cloud” can enable a broad spectrum of analyses useful for personal and public health, clinical analysis, food safety, and environmental monitoring. Although the developed world has many options for analysis and web connection, the developing world does not have broad access to either the expensive equipment necessary to perform these tests or the advanced… Show more

The ability to perform electrochemical testing in the field, and in resource-limited environments, and to transmit data automatically to “the cloud” can enable a broad spectrum of analyses useful for personal and public health, clinical analysis, food safety, and environmental monitoring. Although the developed world has many options for analysis and web connection, the developing world does not have broad access to either the expensive equipment necessary to perform these tests or the advanced technologies required for network connectivity. To overcome these limitations, we have developed a simple, affordable ($25), handheld device that can perform all the most common electrochemical analyses, and transmit the results of testing to the cloud from any phone, over any network, anywhere in the world. Show less

To develop and test an endoscopically implantable wireless biosensor for real-time detection of fluorescein-labeled blood in ex vivo and in vivo porcine models of UGIB. UGIB models were surgically created in living pigs. Biosensors were endoscopically deployed in the stomach using standard endoscopic clips. The ability to detect acute UGIB and estimated blood loss leading to biosensor activation were recorded. Feasibility of wireless data transmission out of the body to an external computer… Show more

To develop and test an endoscopically implantable wireless biosensor for real-time detection of fluorescein-labeled blood in ex vivo and in vivo porcine models of UGIB. UGIB models were surgically created in living pigs. Biosensors were endoscopically deployed in the stomach using standard endoscopic clips. The ability to detect acute UGIB and estimated blood loss leading to biosensor activation were recorded. Feasibility of wireless data transmission out of the body to an external computer and cell phone was assessed. A porcine UGIB model was successfully created. Biosensors were able to detect all acute bleeding events and wirelessly transmit out of the body, and successfully sent an emergency text message to the intended cell phone in all cases. Average estimated blood loss leading to biosensor activation was 30 mL (10–75 mL). Show less

Alkali vapor cells with antirelaxation coated walls can have long atomic coherence times. However, using such coated cells in the hyperfine configuration for electromagnetically induced transparency (EIT) requires longitudinal atomic motion to be confined to less than the hyperfine wavelength. We employed a narrow (1 mm) coated cell geometry to study hyperfine EIT and slow and stored light in warm b vapor, with results comparable to those in buffer gas cells and showing the promise of such… Show more

Alkali vapor cells with antirelaxation coated walls can have long atomic coherence times. However, using such coated cells in the hyperfine configuration for electromagnetically induced transparency (EIT) requires longitudinal atomic motion to be confined to less than the hyperfine wavelength. We employed a narrow (1 mm) coated cell geometry to study hyperfine EIT and slow and stored light in warm b vapor, with results comparable to those in buffer gas cells and showing the promise of such cells for several applications. Show less

Synthetic systems cannot easily mimic the color-changing abilities of animals such as cephalopods. Soft machines—machines fabricated from soft polymers and flexible reinforcing sheets—are rapidly increasing in functionality. This manuscript describes simple microfluidic networks that can change the color, contrast, pattern, apparent shape, luminescence, and surface temperature of soft machines for camouflage and display. The color of these microfluidic networks can be changed simultaneously in… Show more

Synthetic systems cannot easily mimic the color-changing abilities of animals such as cephalopods. Soft machines—machines fabricated from soft polymers and flexible reinforcing sheets—are rapidly increasing in functionality. This manuscript describes simple microfluidic networks that can change the color, contrast, pattern, apparent shape, luminescence, and surface temperature of soft machines for camouflage and display. The color of these microfluidic networks can be changed simultaneously in the visible and infrared—a capability that organisms do not have. These strategies begin to imitate the functions, although not the anatomies, of color-changing animals. Show less