We present a fundamental class of 3D printed microfluidic circuit components and integrated syste... more We present a fundamental class of 3D printed microfluidic circuit components and integrated systems constructed using multijet modelling-based approaches.
2018 IEEE Micro Electro Mechanical Systems (MEMS), 2018
We demonstrate high-force-density rapid actuation of electrostatic gap-closing actuator (GCA) arr... more We demonstrate high-force-density rapid actuation of electrostatic gap-closing actuator (GCA) arrays operating in an aqueous environment. These devices are designed to generate up to 4.6 mN at 6 V drive signal amplitudes and have measured pull-in times as fast as 121 μs with no electrolysis. We present a new model for the dynamics of aqueous GCA operation which includes the inertia of the squeezed fluid and proximity of the substrate to the device layer. The actuators operate in deionized water, and preliminary tests demonstrate actuation in ionic solutions (10 mM) and partial operation of submerged inchworm motors based on GCA arrays.
we present the remote control of insects in free flight via an implantable radio-equipped miniatu... more we present the remote control of insects in free flight via an implantable radio-equipped miniature neural stimulating system. This paper summarizes these results. The pronotum mounted system consisted of neural stimulators, muscular stimulators, a radio transceiver-equipped microcontroller and a microbattery. Flight initiation, cessation and elevation control were accomplished through neural stimulus of the brain which elicited, suppressed or modulated wing oscillation. Turns were triggered through the direct muscular stimulus of either of the basalar muscles. We characterized the response times, success rates, and free-flight trajectories elicited by our neural control systems in remotely-controlled beetles. We believe this type of technology will open the door to in-flight perturbation and recording of insect flight responses. Keywords— micro air vehicle, biological machine, neuromuscular stimulation, flight control
In wireless devices, reducing the time the radio is on results in lower power consumption. In res... more In wireless devices, reducing the time the radio is on results in lower power consumption. In resource-constrained wireless networks, then, sending the same data in fewer bytes can greatly extend the lifetime of the network. In this paper, we explore the use of protocolindependent packet compression, a technique orthogonal to current explicit compaction techniques. Such a compression algorithm functions as a transparent layer inside a communication stack. Because it makes no assumption on the specific protocols used, it is generic enough to be used on multiple technologies. Compression is performed by identifying patterns in recently sent packets and replacing those patterns with bit flags, effectively reducing the size of the packet to be sent. We discuss the trade-offs between computation, memory costs and power savings in such an algorithm. We then present the results of compressing actual packet traces collected from several commercial networks using this algorithm. Results indi...
we present the remote control of insects in free flight via an implantable radio-equipped miniatu... more we present the remote control of insects in free flight via an implantable radio-equipped miniature neural stimulating system. This paper summarizes these results. The pronotum mounted system consisted of neural stimulators, muscular stimulators, a radio transceiver-equipped microcontroller and a microbattery. Flight initiation, cessation and elevation control were accomplished through neural stimulus of the brain which elicited, suppressed or modulated wing oscillation. Turns were triggered through the direct muscular stimulus of either of the basalar muscles. We characterized the response times, success rates, and free-flight trajectories elicited by our neural control systems in remotely-controlled beetles. We believe this type of technology will open the door to in-flight perturbation and recording of insect flight responses. Keywords— micro air vehicle, biological machine, neuromuscular stimulation, flight control
A MEMS actuator, dubbed the MEMS hammer, capable of storing and rapidly releasing mechanical ener... more A MEMS actuator, dubbed the MEMS hammer, capable of storing and rapidly releasing mechanical energy has been designed, built and tested. The hammer is fabricated using a single mask silicon-on-insulator (SOI) process. These devices have been used to study fracture in both lateral and vertical regimes. The lateral tests have shown excellent agreement with shear fracture theory. Using either a mechanical or an electrostatic latching mechanism, the hammers are capable of storing energies up to 3.3μJ. The hammers have been shown to displace up to 36μm, exert a maximum force of 240 mN, move at speeds exceeding 50m/s, and deliver at least 330 mW of mechanical power. INTRODUCTION The goal of this research is to create a microactuator capable of fracturing barriers made of silicon and silicon dioxide. At its core, the MEMS hammer is a device capable of storing and releasing mechanical energy. This system could be used for applications ranging from jumping microrobots [1] to needle-free deli...
Design, Automation & Test in Europe Conference & Exhibition (DATE), 2013, 2013
In the original demonstration of insect flight control [2,4], flight initiation, cessation and el... more In the original demonstration of insect flight control [2,4], flight initiation, cessation and elevation control were accomplished through neural stimulus of the brain which elicited, suppressed or modulated wing oscillation. Turns were triggered through the direct muscular stimulus of either of the basalar muscles. We characterized the response times, success rates, and free-flight trajectories elicited by our neural control systems in remotely controlled beetles.
Objective: Microwire and Utah-style neural recording arrays are the predominant devices used for ... more Objective: Microwire and Utah-style neural recording arrays are the predominant devices used for cortical neural recording, but the implanted electrodes cause a significant adverse biological response and suffer from well-studied performance degradation. Recent work has demonstrated that carbon fiber electrodes do not elicit this same adverse response, but these existing designs are not practically scalable to hundreds or thousands of recording sites. We present technology that overcomes these issues while additionally providing fine electrode pitch for spatial oversampling. Approach: We present a 32-channel carbon fiber monofilament-based intracortical neural recording array fabricated through a combination of bulk silicon microfabrication processing and microassembly. This device represents the first truly two-dimensional carbon fiber neural recording array. The density, channel count, and size scale of this array are enabled by an out-of-plane microassembly technique in which individual fibers are inserted through metallized and isotropically conductive adhesive-filled holes in an oxide-passivated microfabricated silicon substrate. Main results: Five-micron diameter fibers are spaced at a pitch of 38 microns, four times denser than state of the art one-dimensional arrays. The fine diameter of the carbon fibers affords both minimal cross-section and nearly three orders of magnitude greater lateral compliance than standard tungsten microwires. Typical 1 kHz impedances are on the order of hundreds of kiloohms, and successful in vivo recording is demonstrated in the motor cortex of a rat. 22 total units are recorded on 20 channels, with unit SNR ranging from 0.85 to 4.2. Significance: This is the highest density microwire-style electrode array to date, and this fabrication technique is scalable to a larger number of electrodes and allows for the potential future integration of microelectronics. Large-scale carbon fiber neural recording arrays are a promising technology for reducing the inflammatory response and increasing the information density, particularly in neural recording applications where microwire arrays are already used.
Reuse of filtering facepiece respirators (FFRs, commonly referred to as N95s) normally meant for ... more Reuse of filtering facepiece respirators (FFRs, commonly referred to as N95s) normally meant for single use has become common in healthcare facilities due to shortages caused by the COVID-19 pandemic. Here, we report that murine hepatitis coronavirus initially seeded on FFR filter material is inactivated (6 order of magnitude reduction as measured by median tissue culture infective dose, TCID50) after dry heating at 75°C for 30 min. We also find that the quantitative fit of FFRs after heat treatment at this temperature, under dry conditions or at 90% relative humidity, is not affected by single or 10 heating cycles. Previous studies have reported that the filtration efficiency of FFRs is not negatively impacted by these heating conditions. These results suggest that thermal inactivation of coronaviruses is a potentially rapid and widely deployable method to reuse N95 FFRs in emergency situations where reusing FFRs is a necessity and broad-spectrum sterilization is unavailable. Howev...
Re-use of filtering facepiece respirators (FFRs, commonly referred to as N95s) normally meant for... more Re-use of filtering facepiece respirators (FFRs, commonly referred to as N95s) normally meant for single use only is becoming common in healthcare facilities due to shortages caused by the COVID19 pandemic. Here we report that mouse hepatitis virus (MHV) initially seeded on FFR filter material is inactivated (6 log reduction as measured by 50% tissue culture infective dose (TCID50)) after dry heating at 75 °C for 30 minutes. We also find that the quantitative fit of FFRs after heat treatment at this temperature, under dry conditions or at 90% relative humidity, is not affected by single or ten heating cycles. Previous studies have reported that the filtration efficiency of FFR filters is not negatively impacted by these heating conditions. These results suggest that thermal inactivation of coronaviruses is a potentially rapid and widely deployable method to re-use N95 FFRs in emergency situations where re-using FFRs is a necessity and broad-spectrum sterilization is unavailable. How...
Objective: Microwire and Utah-style neural recording arrays are the predominant devices used for ... more Objective: Microwire and Utah-style neural recording arrays are the predominant devices used for cortical neural recording, but the implanted electrodes cause a significant adverse biological response and suffer from well-studied performance degradation. Recent work has demonstrated that carbon fiber electrodes do not elicit this same adverse response, but these existing designs are not practically scalable to hundreds or thousands of recording sites. We present technology that overcomes these issues while additionally providing fine electrode pitch for spatial oversampling. Approach: We present a 32-channel carbon fiber monofilament-based intracortical neural recording array fabricated through a combination of bulk silicon microfabrication processing and microassembly. This device represents the first truly two-dimensional carbon fiber neural recording array. The density, channel count, and size scale of this array are enabled by an out-of-plane microassembly technique in which individual fibers are inserted through metallized and isotropically conductive adhesive-filled holes in an oxide-passivated microfabricated silicon substrate. Main results: Five-micron diameter fibers are spaced at a pitch of 38 microns, four times denser than state of the art one-dimensional arrays. The fine diameter of the carbon fibers affords both minimal cross-section and nearly three orders of magnitude greater lateral compliance than standard tungsten microwires. Typical 1 kHz impedances are on the order of hundreds of kiloohms, and successful in vivo recording is demonstrated in the motor cortex of a rat. 22 total units are recorded on 20 channels, with unit SNR ranging from 0.85 to 4.2. Significance: This is the highest density microwire-style electrode array to date, and this fabrication technique is scalable to a larger number of electrodes and allows for the potential future integration of microelectronics. Large-scale carbon fiber neural recording arrays are a promising technology for reducing the inflammatory response and increasing the information density, particularly in neural recording applications where microwire arrays are already used.
Microwire and microelectrode arrays used for cortical neural recording typically consist of tens ... more Microwire and microelectrode arrays used for cortical neural recording typically consist of tens to hundreds of recording sites, but often only a fraction of these sites are in close enough proximity to firing neurons to record singleunit activity. Recent work has demonstrated precise, depthcontrollable mechanisms for the insertion of single neural recording electrodes, but these methods are mostly only capable of inserting electrodes which elicit adverse biological response. We present an electrostatic-based actuator capable of inserting individual carbon fiber microelectrodes which elicit minimal to no adverse biological response. The device is shown to insert a carbon fiber recording electrode into an agar brain phantom and can record an artificial neural signal in saline. This technique provides a platform generalizable to many microwire-style recording electrodes.
Glial encapsulation of chronically implanted neural probes inhibits recording and stimulation, an... more Glial encapsulation of chronically implanted neural probes inhibits recording and stimulation, and this signal loss is a significant factor limiting the clinical viability of most neural implant topologies for decades-long implantation. We demonstrate a mechanical proof of concept for silicon shank-style neural probes intended to minimize gliosis near the recording sites. Compliant whiskers on the edges of the probe fold inward to minimize tissue damage during insertion. Once implanted to the target depth and retracted slightly, these whiskers splay outward. The splayed tips, on which recording sites could be patterned, extend beyond the typical 50-100 micron radius of a glial scar. The whiskers are micron-scale to minimize or avoid glial scarring. Electrically inactive devices with whiskers of varying widths and curvature were designed and monolithically fabricated from a five-micron silicon-oninsulator (SOI) wafer, and their mechanical functionality was demonstrated in a 0.6% agar brain phantom. Deflection was plotted versus deflection speed, and those that were most compliant actuated successfully. This probe requires no preparation for use beyond what is typical for a shank-style silicon probe.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2018
Eliciting predictable flight responses in insects via exogenous stimulation of the nervous system... more Eliciting predictable flight responses in insects via exogenous stimulation of the nervous system is an area of both scientific and engineering interest. Blowflies in particular possess an excellent biological flight control system, making them an ideal system for characterising responses to stimulation. Here we demonstrate a means of electrically controlling Calliphoridae-Protophormia terranovae wing behaviour, generating a repeatable yaw response via biphasic electrical stimulation of the H1 lobula plate tangential cell (LPTC). We found that a 10 mA current pulse at a frequency of 30-270 Hz produces a yaw response in the preferred direction of H1 in a tethered blowfly preparation, and the magnitude of the yaw response is proportional to the frequency of the stimulus. This result suggests that these LPTCs, which encode optic flow, may be a viable interface for controlling fly flight behaviour. This platform could find application not only for micro air vehicles (MAVs), but also in ...
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2014
Linking neurons and muscles to their roles in behavior requires not only the ability to measure t... more Linking neurons and muscles to their roles in behavior requires not only the ability to measure their response during unrestrained movement but also the ability to stimulate them and observe the behavioral results. Current wireless stimulation technologies can be carried by rodent-sized animals and very large insects. However, the mass and volume of these devices make them impractical for studying smaller animals like insects. Here we present a battery-powered electronics platform suitable to be carried on a flying locust (2.7 g). The device has an IR-based (infrared) receiver, can deliver optical or electrical stimulation, occupies a volume of 0.1 cm(3), and weighs ~280 mg. We show the device is capable of powering two white SMD light emitting diodes (LEDs) for ~4 min and can be recharged in ~20 min. We demonstrate that our system shows no crosstalk with an IR-based Vicon tracking system. The entire package is made from commercial off-the-shelf components and requires no microfabri...
Highlights d Developed a miniature radio system to remotely stimulate free-flying insects d Grade... more Highlights d Developed a miniature radio system to remotely stimulate free-flying insects d Graded and controlled turns in free-flying insects by electrical stimulation d Demonstrated the coleopteran third axillary muscle is tonically activated ipsilaterally during turns
ABSTRACT For angiography, stem cell imaging, and cancer imaging, magnetic particle imaging (MPI) ... more ABSTRACT For angiography, stem cell imaging, and cancer imaging, magnetic particle imaging (MPI) can replace conventional techniques due to its safety in vivo, exquisite image contrast, and high detection sensitivity. However, compared to the theoretical physical sensitivity limit of a MPI scanner with 1 mm3 resolution using image 17 nm iron oxide nanoparticles, which lies between 100 nM and 1 μM1, the detection sensitivity for current MPI systems is worse by over 4 orders of magnitude. Factors contributing to this lack of sensitivity include non-optimal noise matching and feedthrough interference, of which the latter is a more dominant effect due to spectral overlap between the interfering signals and particle signals. Gleich et al., Schmale et al. and the authors of this study have previously attempted to decrease the interference through high-power filters and reducing capacitor distortion. In this work, we attempt to actively cancel interfering magnetic fields through the use of a feedforward transformer coupling circuit.
We present a fundamental class of 3D printed microfluidic circuit components and integrated syste... more We present a fundamental class of 3D printed microfluidic circuit components and integrated systems constructed using multijet modelling-based approaches.
2018 IEEE Micro Electro Mechanical Systems (MEMS), 2018
We demonstrate high-force-density rapid actuation of electrostatic gap-closing actuator (GCA) arr... more We demonstrate high-force-density rapid actuation of electrostatic gap-closing actuator (GCA) arrays operating in an aqueous environment. These devices are designed to generate up to 4.6 mN at 6 V drive signal amplitudes and have measured pull-in times as fast as 121 μs with no electrolysis. We present a new model for the dynamics of aqueous GCA operation which includes the inertia of the squeezed fluid and proximity of the substrate to the device layer. The actuators operate in deionized water, and preliminary tests demonstrate actuation in ionic solutions (10 mM) and partial operation of submerged inchworm motors based on GCA arrays.
we present the remote control of insects in free flight via an implantable radio-equipped miniatu... more we present the remote control of insects in free flight via an implantable radio-equipped miniature neural stimulating system. This paper summarizes these results. The pronotum mounted system consisted of neural stimulators, muscular stimulators, a radio transceiver-equipped microcontroller and a microbattery. Flight initiation, cessation and elevation control were accomplished through neural stimulus of the brain which elicited, suppressed or modulated wing oscillation. Turns were triggered through the direct muscular stimulus of either of the basalar muscles. We characterized the response times, success rates, and free-flight trajectories elicited by our neural control systems in remotely-controlled beetles. We believe this type of technology will open the door to in-flight perturbation and recording of insect flight responses. Keywords— micro air vehicle, biological machine, neuromuscular stimulation, flight control
In wireless devices, reducing the time the radio is on results in lower power consumption. In res... more In wireless devices, reducing the time the radio is on results in lower power consumption. In resource-constrained wireless networks, then, sending the same data in fewer bytes can greatly extend the lifetime of the network. In this paper, we explore the use of protocolindependent packet compression, a technique orthogonal to current explicit compaction techniques. Such a compression algorithm functions as a transparent layer inside a communication stack. Because it makes no assumption on the specific protocols used, it is generic enough to be used on multiple technologies. Compression is performed by identifying patterns in recently sent packets and replacing those patterns with bit flags, effectively reducing the size of the packet to be sent. We discuss the trade-offs between computation, memory costs and power savings in such an algorithm. We then present the results of compressing actual packet traces collected from several commercial networks using this algorithm. Results indi...
we present the remote control of insects in free flight via an implantable radio-equipped miniatu... more we present the remote control of insects in free flight via an implantable radio-equipped miniature neural stimulating system. This paper summarizes these results. The pronotum mounted system consisted of neural stimulators, muscular stimulators, a radio transceiver-equipped microcontroller and a microbattery. Flight initiation, cessation and elevation control were accomplished through neural stimulus of the brain which elicited, suppressed or modulated wing oscillation. Turns were triggered through the direct muscular stimulus of either of the basalar muscles. We characterized the response times, success rates, and free-flight trajectories elicited by our neural control systems in remotely-controlled beetles. We believe this type of technology will open the door to in-flight perturbation and recording of insect flight responses. Keywords— micro air vehicle, biological machine, neuromuscular stimulation, flight control
A MEMS actuator, dubbed the MEMS hammer, capable of storing and rapidly releasing mechanical ener... more A MEMS actuator, dubbed the MEMS hammer, capable of storing and rapidly releasing mechanical energy has been designed, built and tested. The hammer is fabricated using a single mask silicon-on-insulator (SOI) process. These devices have been used to study fracture in both lateral and vertical regimes. The lateral tests have shown excellent agreement with shear fracture theory. Using either a mechanical or an electrostatic latching mechanism, the hammers are capable of storing energies up to 3.3μJ. The hammers have been shown to displace up to 36μm, exert a maximum force of 240 mN, move at speeds exceeding 50m/s, and deliver at least 330 mW of mechanical power. INTRODUCTION The goal of this research is to create a microactuator capable of fracturing barriers made of silicon and silicon dioxide. At its core, the MEMS hammer is a device capable of storing and releasing mechanical energy. This system could be used for applications ranging from jumping microrobots [1] to needle-free deli...
Design, Automation & Test in Europe Conference & Exhibition (DATE), 2013, 2013
In the original demonstration of insect flight control [2,4], flight initiation, cessation and el... more In the original demonstration of insect flight control [2,4], flight initiation, cessation and elevation control were accomplished through neural stimulus of the brain which elicited, suppressed or modulated wing oscillation. Turns were triggered through the direct muscular stimulus of either of the basalar muscles. We characterized the response times, success rates, and free-flight trajectories elicited by our neural control systems in remotely controlled beetles.
Objective: Microwire and Utah-style neural recording arrays are the predominant devices used for ... more Objective: Microwire and Utah-style neural recording arrays are the predominant devices used for cortical neural recording, but the implanted electrodes cause a significant adverse biological response and suffer from well-studied performance degradation. Recent work has demonstrated that carbon fiber electrodes do not elicit this same adverse response, but these existing designs are not practically scalable to hundreds or thousands of recording sites. We present technology that overcomes these issues while additionally providing fine electrode pitch for spatial oversampling. Approach: We present a 32-channel carbon fiber monofilament-based intracortical neural recording array fabricated through a combination of bulk silicon microfabrication processing and microassembly. This device represents the first truly two-dimensional carbon fiber neural recording array. The density, channel count, and size scale of this array are enabled by an out-of-plane microassembly technique in which individual fibers are inserted through metallized and isotropically conductive adhesive-filled holes in an oxide-passivated microfabricated silicon substrate. Main results: Five-micron diameter fibers are spaced at a pitch of 38 microns, four times denser than state of the art one-dimensional arrays. The fine diameter of the carbon fibers affords both minimal cross-section and nearly three orders of magnitude greater lateral compliance than standard tungsten microwires. Typical 1 kHz impedances are on the order of hundreds of kiloohms, and successful in vivo recording is demonstrated in the motor cortex of a rat. 22 total units are recorded on 20 channels, with unit SNR ranging from 0.85 to 4.2. Significance: This is the highest density microwire-style electrode array to date, and this fabrication technique is scalable to a larger number of electrodes and allows for the potential future integration of microelectronics. Large-scale carbon fiber neural recording arrays are a promising technology for reducing the inflammatory response and increasing the information density, particularly in neural recording applications where microwire arrays are already used.
Reuse of filtering facepiece respirators (FFRs, commonly referred to as N95s) normally meant for ... more Reuse of filtering facepiece respirators (FFRs, commonly referred to as N95s) normally meant for single use has become common in healthcare facilities due to shortages caused by the COVID-19 pandemic. Here, we report that murine hepatitis coronavirus initially seeded on FFR filter material is inactivated (6 order of magnitude reduction as measured by median tissue culture infective dose, TCID50) after dry heating at 75°C for 30 min. We also find that the quantitative fit of FFRs after heat treatment at this temperature, under dry conditions or at 90% relative humidity, is not affected by single or 10 heating cycles. Previous studies have reported that the filtration efficiency of FFRs is not negatively impacted by these heating conditions. These results suggest that thermal inactivation of coronaviruses is a potentially rapid and widely deployable method to reuse N95 FFRs in emergency situations where reusing FFRs is a necessity and broad-spectrum sterilization is unavailable. Howev...
Re-use of filtering facepiece respirators (FFRs, commonly referred to as N95s) normally meant for... more Re-use of filtering facepiece respirators (FFRs, commonly referred to as N95s) normally meant for single use only is becoming common in healthcare facilities due to shortages caused by the COVID19 pandemic. Here we report that mouse hepatitis virus (MHV) initially seeded on FFR filter material is inactivated (6 log reduction as measured by 50% tissue culture infective dose (TCID50)) after dry heating at 75 °C for 30 minutes. We also find that the quantitative fit of FFRs after heat treatment at this temperature, under dry conditions or at 90% relative humidity, is not affected by single or ten heating cycles. Previous studies have reported that the filtration efficiency of FFR filters is not negatively impacted by these heating conditions. These results suggest that thermal inactivation of coronaviruses is a potentially rapid and widely deployable method to re-use N95 FFRs in emergency situations where re-using FFRs is a necessity and broad-spectrum sterilization is unavailable. How...
Objective: Microwire and Utah-style neural recording arrays are the predominant devices used for ... more Objective: Microwire and Utah-style neural recording arrays are the predominant devices used for cortical neural recording, but the implanted electrodes cause a significant adverse biological response and suffer from well-studied performance degradation. Recent work has demonstrated that carbon fiber electrodes do not elicit this same adverse response, but these existing designs are not practically scalable to hundreds or thousands of recording sites. We present technology that overcomes these issues while additionally providing fine electrode pitch for spatial oversampling. Approach: We present a 32-channel carbon fiber monofilament-based intracortical neural recording array fabricated through a combination of bulk silicon microfabrication processing and microassembly. This device represents the first truly two-dimensional carbon fiber neural recording array. The density, channel count, and size scale of this array are enabled by an out-of-plane microassembly technique in which individual fibers are inserted through metallized and isotropically conductive adhesive-filled holes in an oxide-passivated microfabricated silicon substrate. Main results: Five-micron diameter fibers are spaced at a pitch of 38 microns, four times denser than state of the art one-dimensional arrays. The fine diameter of the carbon fibers affords both minimal cross-section and nearly three orders of magnitude greater lateral compliance than standard tungsten microwires. Typical 1 kHz impedances are on the order of hundreds of kiloohms, and successful in vivo recording is demonstrated in the motor cortex of a rat. 22 total units are recorded on 20 channels, with unit SNR ranging from 0.85 to 4.2. Significance: This is the highest density microwire-style electrode array to date, and this fabrication technique is scalable to a larger number of electrodes and allows for the potential future integration of microelectronics. Large-scale carbon fiber neural recording arrays are a promising technology for reducing the inflammatory response and increasing the information density, particularly in neural recording applications where microwire arrays are already used.
Microwire and microelectrode arrays used for cortical neural recording typically consist of tens ... more Microwire and microelectrode arrays used for cortical neural recording typically consist of tens to hundreds of recording sites, but often only a fraction of these sites are in close enough proximity to firing neurons to record singleunit activity. Recent work has demonstrated precise, depthcontrollable mechanisms for the insertion of single neural recording electrodes, but these methods are mostly only capable of inserting electrodes which elicit adverse biological response. We present an electrostatic-based actuator capable of inserting individual carbon fiber microelectrodes which elicit minimal to no adverse biological response. The device is shown to insert a carbon fiber recording electrode into an agar brain phantom and can record an artificial neural signal in saline. This technique provides a platform generalizable to many microwire-style recording electrodes.
Glial encapsulation of chronically implanted neural probes inhibits recording and stimulation, an... more Glial encapsulation of chronically implanted neural probes inhibits recording and stimulation, and this signal loss is a significant factor limiting the clinical viability of most neural implant topologies for decades-long implantation. We demonstrate a mechanical proof of concept for silicon shank-style neural probes intended to minimize gliosis near the recording sites. Compliant whiskers on the edges of the probe fold inward to minimize tissue damage during insertion. Once implanted to the target depth and retracted slightly, these whiskers splay outward. The splayed tips, on which recording sites could be patterned, extend beyond the typical 50-100 micron radius of a glial scar. The whiskers are micron-scale to minimize or avoid glial scarring. Electrically inactive devices with whiskers of varying widths and curvature were designed and monolithically fabricated from a five-micron silicon-oninsulator (SOI) wafer, and their mechanical functionality was demonstrated in a 0.6% agar brain phantom. Deflection was plotted versus deflection speed, and those that were most compliant actuated successfully. This probe requires no preparation for use beyond what is typical for a shank-style silicon probe.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2018
Eliciting predictable flight responses in insects via exogenous stimulation of the nervous system... more Eliciting predictable flight responses in insects via exogenous stimulation of the nervous system is an area of both scientific and engineering interest. Blowflies in particular possess an excellent biological flight control system, making them an ideal system for characterising responses to stimulation. Here we demonstrate a means of electrically controlling Calliphoridae-Protophormia terranovae wing behaviour, generating a repeatable yaw response via biphasic electrical stimulation of the H1 lobula plate tangential cell (LPTC). We found that a 10 mA current pulse at a frequency of 30-270 Hz produces a yaw response in the preferred direction of H1 in a tethered blowfly preparation, and the magnitude of the yaw response is proportional to the frequency of the stimulus. This result suggests that these LPTCs, which encode optic flow, may be a viable interface for controlling fly flight behaviour. This platform could find application not only for micro air vehicles (MAVs), but also in ...
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2014
Linking neurons and muscles to their roles in behavior requires not only the ability to measure t... more Linking neurons and muscles to their roles in behavior requires not only the ability to measure their response during unrestrained movement but also the ability to stimulate them and observe the behavioral results. Current wireless stimulation technologies can be carried by rodent-sized animals and very large insects. However, the mass and volume of these devices make them impractical for studying smaller animals like insects. Here we present a battery-powered electronics platform suitable to be carried on a flying locust (2.7 g). The device has an IR-based (infrared) receiver, can deliver optical or electrical stimulation, occupies a volume of 0.1 cm(3), and weighs ~280 mg. We show the device is capable of powering two white SMD light emitting diodes (LEDs) for ~4 min and can be recharged in ~20 min. We demonstrate that our system shows no crosstalk with an IR-based Vicon tracking system. The entire package is made from commercial off-the-shelf components and requires no microfabri...
Highlights d Developed a miniature radio system to remotely stimulate free-flying insects d Grade... more Highlights d Developed a miniature radio system to remotely stimulate free-flying insects d Graded and controlled turns in free-flying insects by electrical stimulation d Demonstrated the coleopteran third axillary muscle is tonically activated ipsilaterally during turns
ABSTRACT For angiography, stem cell imaging, and cancer imaging, magnetic particle imaging (MPI) ... more ABSTRACT For angiography, stem cell imaging, and cancer imaging, magnetic particle imaging (MPI) can replace conventional techniques due to its safety in vivo, exquisite image contrast, and high detection sensitivity. However, compared to the theoretical physical sensitivity limit of a MPI scanner with 1 mm3 resolution using image 17 nm iron oxide nanoparticles, which lies between 100 nM and 1 μM1, the detection sensitivity for current MPI systems is worse by over 4 orders of magnitude. Factors contributing to this lack of sensitivity include non-optimal noise matching and feedthrough interference, of which the latter is a more dominant effect due to spectral overlap between the interfering signals and particle signals. Gleich et al., Schmale et al. and the authors of this study have previously attempted to decrease the interference through high-power filters and reducing capacitor distortion. In this work, we attempt to actively cancel interfering magnetic fields through the use of a feedforward transformer coupling circuit.
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Papers by Travis Massey