I design devices and investigate why they fail.
A biphasic cuirass ventilator. One blower and one rotary valve. The disc has four holes, joined in two pairs by curved slots. A quarter turn changes the shell from negative to positive pressure.
A fluidic oscillator with no moving parts. A wedge splits the flow into two channels. A vortex next to the wedge holds the stream on the patient channel. At peak pressure the vortex collapses, and the stream moves to the second channel.
A thruster on top of the feet of the swimmer. A motion sensor detects each kick, and the thruster adds a burst of thrust.
Functional near-infrared spectroscopy for stroke models in small animals. A light source and a detector sit on the skull. Near-infrared light goes through the tissue, and the blood absorbs a part of it. The detected light shows how the blood oxygenation changes during a stroke.
A method to calibrate an implanted intracranial pressure sensor from outside the head. A vibration of known strength is applied to the head, and the response of the sensor is used for the calibration.
A guide for the placement of a feeding tube. A strong magnet on the outside of the neck pushes the tip of the tube away from the airway and toward the esophagus, so that feeding fluid cannot go into the lungs.
A ring that measures blood oxygen, and a wrist unit that measures blood pressure. Together they give the pressure waveform for every beat, through the day and the night. Thus you can see short pressure spikes and when they occur, also during sleep. One or two cuff measurements each day give limited information. The values in the figure are examples.
The foam in the air path of a sleep-therapy device can degrade into particles, and the particles can enter the air path.
Deposits can collect on the flow sensor in the air path of a ventilator. The sensor can then show more flow than there is. The ventilator reads the error as patient effort, and the breath trigger starts to operate at random, out of step with the patient.
A heater-cooler unit controls the temperature of the blood with water. The water in the tanks can become contaminated. The fan of the unit can then send aerosol into the operating room, and the aerosol can get to the operating field. Stop the fan to see the difference.
A blower sends warm air into a blanket on the patient. The warm air goes up at the blower side of the table. The laminar flow from the ceiling pushes it down again, and a slow vortex forms above the patient. Particles from the blower and from the floor can go around in the vortex and come down slowly onto the surgical site. Stop the warming to see the difference.
The collar of the tip is soldered to the tube. In each heat cycle the collar and the tube expand away from the center of the tube and contract back toward it, by different amounts. They also move a little along the tube. Over many cycles this can break the solder, and then the tip comes off.
Nine frames, reserved for the first series.
Engineer, Philadelphia.
Electronics, firmware, mechanics and test, from first concept to preproduction units.
Failure analysis of devices for litigation, through Alpha Devices.