non-invasive ultrasonic bubble sensor for detecting and estimating the size of bubbles flowing inside a tube.

the sensor uses piezoelectric ultrasonic crystals, a continuous sine drive signal, envelope detection, adc thresholding, and firmware timing logic. three possible configurations:

1. single vertical crystal pair for detecting extremely tiny bubbles (around 2% of tube id) using an adjustable threshold.

2. two vertical crystal pairs for detecting extremely tiny bubbles and estimating size of single bubbles from speed and attenuation duration (maximum error below 0.5 µl).

3. two horizontal crystal pairs for detecting >40% tube-occupancy bubbles and adjacent bubbles can be separated more reliably.

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first prototype (sla, before mass production in abs)

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developed designs for five tube sizes: 3/16", 1/4", 5/16", 3/8", and 1/2" OD. Created only two lid compression notch designs to reduce manufacturing costs while ensuring all tubes remain centered at the crystal's mid-height.

assembly view:

composed by a main housing, lid, bottom cover, knurled pins, clamp-on hook, threaded inserts, piezoelectric crystals, custom pcb, and a molex connector.

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50 nL (2% tube ID)

developed:

- part files
- assembly files
*following are redacted for confidentiality*
- fea / dfm / dfa
- product configuration
- product specification
- drawing files: injection molding and machining
- assembly flow chart for manufacturing
- assembly procedures for manufacturing

developed bottom cover to replace potting method adopted by the company in most sensors. Simplified assembly workflow and decreased manufacturing time/piece by 50%.

the Learning Untethered Amphibious Robotic Turtle (LUART) is a platform for studying cost of transport, cost of morphing, and shape/stiffness adaptation in soft robotic flippers.

i was responsible for integrating the flipper technology and waterproofing the entire system, including the chassis, flipper joints, camera systems, wiring, and all electronic components.

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waterproof parts

the electronic components are stored in a acryllic cylinder sealed by lids with o-rings capable to withstand 30 psi. The interface between the motors, computer and air pump is done through PVC tubing and connectors spread across the entire robot.

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flipper technology

for morphing into and maintaining flipper and leg shapes, the limb combines kirigami layer jamming with an internal pouch actuator. The internal pouch deforms the layers and induces a bend in the limb's tip through a cable mechanism, while layer jamming functions as a variable stiffness component that softens for morphing and stiffens to hold a target shape.

layer jamming research

researched and tested different fluids, incluiding a cornstarch slurry, a non-newtonian liquid, between the layers to achieve high stiffness when applying suction in the pouch.
for the test setup, used in 3-point instrom to test specimens that contained 20 layers and 2 tubes for air input and output.

deep water

designed machinable modular and interconnected waterproof housings for Dynamixel motors to withstand 30 psi through exposed shaft sealing interfaces, replacing the original method of using silicone pouches to protect the motors and the wiring.

the mechanism works with a oil seal responsible for isolating the motor while its shaft its rotating, and with the external pressure naturally higher, the seal expands and impedes water from entering the case.

to test the sealing mechanism, in the pictures above, the machined housing was placed inside a pressure chamber with multiple sensors to look for any sort of pressure equalization (leak) while the shaft was rotating.

non-invasive test setup for bubble detection in stainless steel tubing.

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achieved consistent binary bubble detection in 0.25OD and 0.096ID stainless steel tube and repeatable attenuation peaks during bubble (slug) passage.

layers:

housing
compliant material
crystal
coupling gel

stainless steel tubing

coupling gel
crystal
compliant material
housing

test housings for piezoelectric crystal characterization and research

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the design support a slot for a 4-pin header that connects to BNC cables to an oscilloscope and function generator for data collection

developed a fully parametrized file to quickly modify housing for different tube sizes and crystal specifications for different tests.

the housing is modified based on following inputs: - tube OD
- compression percentage
- crystal diameter, thickness and frequency
- wall thickness (for contructive interference based on crystal's frequency. The calculation is made directly on the file by a lambda multiplier)
- compression notch size
- crystal's soldering point diameter

tested 20 different piezoelectric crystals and multiple parameters for sensor optimization

crystal characterization:
- crystal material
- crystal frequency
- crystal size to tube ratio
- drive voltage
- pulse count
- wave type

tubing characterization:
- material
- durometer
- wall thickness
- size
- creep
- fit/coupling

test setup: syringe pumps, microscopic camera for bubble size validation, crystal housings (oscilloscope trigger and data acquisition), power supply, oscilloscope, fuction generator.

the setup above was automated through a softare that is connected to the syringe pumps and activate them sequentially to generate the bubbles, position them below the camera and finally through the crystals for data acquisition

Street architectural details tracing high-contrast patterns and urban geometries.

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2 solar panels (125 watts and 18 volts each)
2 discarded bycicles
metalon bars
2 discarded seats (from a old model airplane)
MPPT charge controller
2 in-wheel motors (360 watts and 48 volts each)
li-ion Battery (48 volts)
motorcycle acceleration system

robotic arm wrist with 3-point controlable stiffness powered by servo motors.

designed multiple modular parts for different setups to test and plot arm and ball joint torque with different currents in the motors.