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Research paper thumbnail of Accelerated project-based introduction to EECS for high school students

Accelerated project-based introduction to EECS for high school students

Introducing students to Electrical Engineering and Computer Science (EECS) can be difficult to im... more Introducing students to Electrical Engineering and Computer Science (EECS) can be difficult to implement within the limited time constraints often encountered in high school summer programs because of the large amount instruction and theory needed to enable suitably complex projects. Projects of meaningful complexity require carefully balancing how much theory and design is left to the students or provided by the instructor. Here we present a short one-week project-based course developed in the summer of 2011 that introduced rising high school seniors to core concepts in EECS. Three days of instruction and teaching labs were followed by two days where students designed and constructed devices used in creating a solar-powered mobile health clinic. A carefully balanced environment enabled students to progress steadily through the entire process of designing, constructing, and testing their projects. Students then presented their work in a conference-style talk. Details of the course outline, methodology, projects, and results, are presented.

Research paper thumbnail of High-Throughput Single-Cell Manipulation in Brain Tissue

PLOS One, 2012

The complexity of neurons and neuronal circuits in brain tissue requires the genetic manipulation... more The complexity of neurons and neuronal circuits in brain tissue requires the genetic manipulation, labeling, and tracking of single cells. However, current methods for manipulating cells in brain tissue are limited to either bulk techniques, lacking single-cell accuracy, or manual methods that provide single-cell accuracy but at significantly lower throughputs and repeatability. Here, we demonstrate high-throughput, efficient, reliable, and combinatorial delivery of multiple genetic vectors and reagents into targeted cells within the same tissue sample with single-cell accuracy. Our system automatically loads nanoliter-scale volumes of reagents into a micropipette from multiwell plates, targets and transfects single cells in brain tissues using a robust electroporation technique, and finally preps the micropipette by automated cleaning for repeating the transfection cycle. We demonstrate multi-colored labeling of adjacent cells, both in organotypic and acute slices, and transfection of plasmids encoding different protein isoforms into neurons within the same brain tissue for analysis of their effects on linear dendritic spine density. Our platform could also be used to rapidly deliver, both ex vivo and in vivo, a variety of genetic vectors, including optogenetic and cell-type specific agents, as well as fast-acting reagents such as labeling dyes, calcium sensors, and voltage sensors to manipulate and track neuronal circuit activity at single-cell resolution.

Research paper thumbnail of Construction of a femtosecond laser microsurgery system

Research paper thumbnail of Transpiration actuation: the design, fabrication and characterization of biomimetic microactuators driven by the surface tension of water

Journal of Micromechanics and Microengineering, 2006

We have designed, fabricated and characterized large displacement distributed-force polymer actua... more We have designed, fabricated and characterized large displacement distributed-force polymer actuators driven only by the surface tension of water. The devices were inspired by the hygroscopic spore dispersal mechanism in fern sporangia. Microdevices were fabricated through a single mask process using a commercial photo-patternable silicone polymer to mimic the mechanical characteristics of plant cellulose. An analytical model for predicting the microactuator behavior was developed using the principle of virtual work, and a variety of designs were simulated and compared to the empirical data. Fabricated devices experienced tip deflections of more than 3.5 mm and angular rotations of more than 330° due to the surface tension of water. The devices generated forces per unit length of 5.75 mN m-1 to 67.75 mN m-1. We show initial results indicating that the transient water-driven deflections can be manipulated to generate devices that self-assemble into stable configurations. Our model shows that devices should scale well into the submicron regime. Lastly, the actuation mechanism presented may provide a robust method for embedding geometry-programmable and environment-scavenged force generation into common materials.

Research paper thumbnail of Transpiration actuation: the design, fabrication and characterization of biomimetic microactuators driven by the surface tension of water

Journal of Micromechanics and Microengineering, 2006

We have designed, fabricated and characterized large displacement distributed-force polymer actua... more We have designed, fabricated and characterized large displacement distributed-force polymer actuators driven only by the surface tension of water. The devices were inspired by the hygroscopic spore dispersal mechanism in fern sporangia. Microdevices were fabricated through a single mask process using a commercial photo-patternable silicone polymer to mimic the mechanical characteristics of plant cellulose. An analytical model for predicting the microactuator behavior was developed using the principle of virtual work, and a variety of designs were simulated and compared to the empirical data. Fabricated devices experienced tip deflections of more than 3.5 mm and angular rotations of more than 330 • due to the surface tension of water. The devices generated forces per unit length of 5.75 mN m −1 to 67.75 mN m −1 . We show initial results indicating that the transient water-driven deflections can be manipulated to generate devices that self-assemble into stable configurations. Our model shows that devices should scale well into the submicron regime. Lastly, the actuation mechanism presented may provide a robust method for embedding geometry-programmable and environment-scavenged force generation into common materials.

Research paper thumbnail of Charge-pumping in a synthetic leaf for harvesting energy from evaporation-driven flows

Applied Physics Letters, 2009

Inspired by water transport in plants, we present a synthetic, microfabricated ``leaf'' that can ... more Inspired by water transport in plants, we present a synthetic, microfabricated ``leaf'' that can scavenge electrical power from evaporative flow. Evaporation at the surface of the device produces flows with velocities up to 1.5 cm/s within etched microchannels. Gas-liquid interfaces within the channels move across an embedded capacitor at this velocity, generating 250 ms, 10-50 pF transient changes in capacitance. If connected to a rectified charge-pump circuit, each capacitive transient can increase the voltage in a 100 μF storage capacitor by ~2-5 μV. We provide estimates of power density, energy density, and scavenging efficiency.

Research paper thumbnail of Charge-pumping in a synthetic leaf for harvesting energy from evaporation-driven flows

Inspired by water transport in plants, we present a synthetic, microfabricated "leaf" that can sc... more Inspired by water transport in plants, we present a synthetic, microfabricated "leaf" that can scavenge electrical power from evaporative flow. Evaporation at the surface of the device produces flows with velocities up to 1.5 cm/s within etched microchannels. Gas-liquid interfaces within the channels move across an embedded capacitor at this velocity, generating 250 ms, 10-50 pF transient changes in capacitance. If connected to a rectified charge-pump circuit, each capacitive transient can increase the voltage in a 100 F storage capacitor by ϳ2-5 V. We provide estimates of power density, energy density, and scavenging efficiency.

Research paper thumbnail of Charge-pumping in a synthetic leaf for harvesting energy from evaporation-driven flows

Inspired by water transport in plants, we present a synthetic, microfabricated "leaf" that can sc... more Inspired by water transport in plants, we present a synthetic, microfabricated "leaf" that can scavenge electrical power from evaporative flow. Evaporation at the surface of the device produces flows with velocities up to 1.5 cm/s within etched microchannels. Gas-liquid interfaces within the channels move across an embedded capacitor at this velocity, generating 250 ms, 10-50 pF transient changes in capacitance. If connected to a rectified charge-pump circuit, each capacitive transient can increase the voltage in a 100 F storage capacitor by ϳ2-5 V. We provide estimates of power density, energy density, and scavenging efficiency.

Research paper thumbnail of High-Throughput Single-Cell Manipulation in Brain Tissue

The complexity of neurons and neuronal circuits in brain tissue requires the genetic manipulation... more The complexity of neurons and neuronal circuits in brain tissue requires the genetic manipulation, labeling, and tracking of single cells. However, current methods for manipulating cells in brain tissue are limited to either bulk techniques, lacking single-cell accuracy, or manual methods that provide single-cell accuracy but at significantly lower throughputs and repeatability. Here, we demonstrate high-throughput, efficient, reliable, and combinatorial delivery of multiple genetic vectors and reagents into targeted cells within the same tissue sample with single-cell accuracy. Our system automatically loads nanoliter-scale volumes of reagents into a micropipette from multiwell plates, targets and transfects single cells in brain tissues using a robust electroporation technique, and finally preps the micropipette by automated cleaning for repeating the transfection cycle. We demonstrate multi-colored labeling of adjacent cells, both in organotypic and acute slices, and transfection of plasmids encoding different protein isoforms into neurons within the same brain tissue for analysis of their effects on linear dendritic spine density. Our platform could also be used to rapidly deliver, both ex vivo and in vivo, a variety of genetic vectors, including optogenetic and cell-type specific agents, as well as fast-acting reagents such as labeling dyes, calcium sensors, and voltage sensors to manipulate and track neuronal circuit activity at single-cell resolution.

Research paper thumbnail of Accelerated project-based introduction to EECS for high school students

Accelerated project-based introduction to EECS for high school students

Introducing students to Electrical Engineering and Computer Science (EECS) can be difficult to im... more Introducing students to Electrical Engineering and Computer Science (EECS) can be difficult to implement within the limited time constraints often encountered in high school summer programs because of the large amount instruction and theory needed to enable suitably complex projects. Projects of meaningful complexity require carefully balancing how much theory and design is left to the students or provided by the instructor. Here we present a short one-week project-based course developed in the summer of 2011 that introduced rising high school seniors to core concepts in EECS. Three days of instruction and teaching labs were followed by two days where students designed and constructed devices used in creating a solar-powered mobile health clinic. A carefully balanced environment enabled students to progress steadily through the entire process of designing, constructing, and testing their projects. Students then presented their work in a conference-style talk. Details of the course outline, methodology, projects, and results, are presented.

Research paper thumbnail of High-Throughput Single-Cell Manipulation in Brain Tissue

PLOS One, 2012

The complexity of neurons and neuronal circuits in brain tissue requires the genetic manipulation... more The complexity of neurons and neuronal circuits in brain tissue requires the genetic manipulation, labeling, and tracking of single cells. However, current methods for manipulating cells in brain tissue are limited to either bulk techniques, lacking single-cell accuracy, or manual methods that provide single-cell accuracy but at significantly lower throughputs and repeatability. Here, we demonstrate high-throughput, efficient, reliable, and combinatorial delivery of multiple genetic vectors and reagents into targeted cells within the same tissue sample with single-cell accuracy. Our system automatically loads nanoliter-scale volumes of reagents into a micropipette from multiwell plates, targets and transfects single cells in brain tissues using a robust electroporation technique, and finally preps the micropipette by automated cleaning for repeating the transfection cycle. We demonstrate multi-colored labeling of adjacent cells, both in organotypic and acute slices, and transfection of plasmids encoding different protein isoforms into neurons within the same brain tissue for analysis of their effects on linear dendritic spine density. Our platform could also be used to rapidly deliver, both ex vivo and in vivo, a variety of genetic vectors, including optogenetic and cell-type specific agents, as well as fast-acting reagents such as labeling dyes, calcium sensors, and voltage sensors to manipulate and track neuronal circuit activity at single-cell resolution.

Research paper thumbnail of Construction of a femtosecond laser microsurgery system

Research paper thumbnail of Transpiration actuation: the design, fabrication and characterization of biomimetic microactuators driven by the surface tension of water

Journal of Micromechanics and Microengineering, 2006

We have designed, fabricated and characterized large displacement distributed-force polymer actua... more We have designed, fabricated and characterized large displacement distributed-force polymer actuators driven only by the surface tension of water. The devices were inspired by the hygroscopic spore dispersal mechanism in fern sporangia. Microdevices were fabricated through a single mask process using a commercial photo-patternable silicone polymer to mimic the mechanical characteristics of plant cellulose. An analytical model for predicting the microactuator behavior was developed using the principle of virtual work, and a variety of designs were simulated and compared to the empirical data. Fabricated devices experienced tip deflections of more than 3.5 mm and angular rotations of more than 330° due to the surface tension of water. The devices generated forces per unit length of 5.75 mN m-1 to 67.75 mN m-1. We show initial results indicating that the transient water-driven deflections can be manipulated to generate devices that self-assemble into stable configurations. Our model shows that devices should scale well into the submicron regime. Lastly, the actuation mechanism presented may provide a robust method for embedding geometry-programmable and environment-scavenged force generation into common materials.

Research paper thumbnail of Transpiration actuation: the design, fabrication and characterization of biomimetic microactuators driven by the surface tension of water

Journal of Micromechanics and Microengineering, 2006

We have designed, fabricated and characterized large displacement distributed-force polymer actua... more We have designed, fabricated and characterized large displacement distributed-force polymer actuators driven only by the surface tension of water. The devices were inspired by the hygroscopic spore dispersal mechanism in fern sporangia. Microdevices were fabricated through a single mask process using a commercial photo-patternable silicone polymer to mimic the mechanical characteristics of plant cellulose. An analytical model for predicting the microactuator behavior was developed using the principle of virtual work, and a variety of designs were simulated and compared to the empirical data. Fabricated devices experienced tip deflections of more than 3.5 mm and angular rotations of more than 330 • due to the surface tension of water. The devices generated forces per unit length of 5.75 mN m −1 to 67.75 mN m −1 . We show initial results indicating that the transient water-driven deflections can be manipulated to generate devices that self-assemble into stable configurations. Our model shows that devices should scale well into the submicron regime. Lastly, the actuation mechanism presented may provide a robust method for embedding geometry-programmable and environment-scavenged force generation into common materials.

Research paper thumbnail of Charge-pumping in a synthetic leaf for harvesting energy from evaporation-driven flows

Applied Physics Letters, 2009

Inspired by water transport in plants, we present a synthetic, microfabricated ``leaf'' that can ... more Inspired by water transport in plants, we present a synthetic, microfabricated ``leaf'' that can scavenge electrical power from evaporative flow. Evaporation at the surface of the device produces flows with velocities up to 1.5 cm/s within etched microchannels. Gas-liquid interfaces within the channels move across an embedded capacitor at this velocity, generating 250 ms, 10-50 pF transient changes in capacitance. If connected to a rectified charge-pump circuit, each capacitive transient can increase the voltage in a 100 μF storage capacitor by ~2-5 μV. We provide estimates of power density, energy density, and scavenging efficiency.

Research paper thumbnail of Charge-pumping in a synthetic leaf for harvesting energy from evaporation-driven flows

Inspired by water transport in plants, we present a synthetic, microfabricated "leaf" that can sc... more Inspired by water transport in plants, we present a synthetic, microfabricated "leaf" that can scavenge electrical power from evaporative flow. Evaporation at the surface of the device produces flows with velocities up to 1.5 cm/s within etched microchannels. Gas-liquid interfaces within the channels move across an embedded capacitor at this velocity, generating 250 ms, 10-50 pF transient changes in capacitance. If connected to a rectified charge-pump circuit, each capacitive transient can increase the voltage in a 100 F storage capacitor by ϳ2-5 V. We provide estimates of power density, energy density, and scavenging efficiency.

Research paper thumbnail of Charge-pumping in a synthetic leaf for harvesting energy from evaporation-driven flows

Inspired by water transport in plants, we present a synthetic, microfabricated "leaf" that can sc... more Inspired by water transport in plants, we present a synthetic, microfabricated "leaf" that can scavenge electrical power from evaporative flow. Evaporation at the surface of the device produces flows with velocities up to 1.5 cm/s within etched microchannels. Gas-liquid interfaces within the channels move across an embedded capacitor at this velocity, generating 250 ms, 10-50 pF transient changes in capacitance. If connected to a rectified charge-pump circuit, each capacitive transient can increase the voltage in a 100 F storage capacitor by ϳ2-5 V. We provide estimates of power density, energy density, and scavenging efficiency.

Research paper thumbnail of High-Throughput Single-Cell Manipulation in Brain Tissue

The complexity of neurons and neuronal circuits in brain tissue requires the genetic manipulation... more The complexity of neurons and neuronal circuits in brain tissue requires the genetic manipulation, labeling, and tracking of single cells. However, current methods for manipulating cells in brain tissue are limited to either bulk techniques, lacking single-cell accuracy, or manual methods that provide single-cell accuracy but at significantly lower throughputs and repeatability. Here, we demonstrate high-throughput, efficient, reliable, and combinatorial delivery of multiple genetic vectors and reagents into targeted cells within the same tissue sample with single-cell accuracy. Our system automatically loads nanoliter-scale volumes of reagents into a micropipette from multiwell plates, targets and transfects single cells in brain tissues using a robust electroporation technique, and finally preps the micropipette by automated cleaning for repeating the transfection cycle. We demonstrate multi-colored labeling of adjacent cells, both in organotypic and acute slices, and transfection of plasmids encoding different protein isoforms into neurons within the same brain tissue for analysis of their effects on linear dendritic spine density. Our platform could also be used to rapidly deliver, both ex vivo and in vivo, a variety of genetic vectors, including optogenetic and cell-type specific agents, as well as fast-acting reagents such as labeling dyes, calcium sensors, and voltage sensors to manipulate and track neuronal circuit activity at single-cell resolution.