Design of a oil and gas pressure sensor system
A new pressure sensor design for oil and gas applications required a dry-mate connector assembly to convey pressure to the sensor. Due to extreme pressures in the well during completion, the sensor and connector assembly would be required to survive pressurization to over 25,000 psi of internal pressure. Detailed analysis using theoretical calculations and FEA were required to drive the design and ensure a successful solution.
Space is tight inside an oil and gas well. The entire assembly shown above has to fit inside a 4″-6″ bore diameter and the sensor has a diameter of 0.375″ and is welded to a 0.25″ cable. The dry-mate connector needed to be as compact as possible, while providing protection to sensitive components. The final design of the two part dry-mate connector came in at only 0.66″ tall x 1.0″ wide x 2.25″ long.
Design and construction of a custom laser control module
A customer wanted to operate a distributed feedback (DFB) laser under pulsed operating conditions in their medical research. There was not an “off the shelf” solution readily available to properly operate the laser as desired. To aid the customer, a control module was rapidly was designed and built. This enabled them to skip past the exercise of researching, specifying, procuring and building a laser control system. With this system in place, they were able to begin using the laser in their research without delay. Some of the key components in this design are;
- A thermoelectric cooler (TEC) controller to regulate the laser TEC and control its temperature.
- A TEC cold plate and second TEC controller to regulate the cold plate base temperature, ensuring the laser base temperature is properly maintained. This ensures the laser’s internal TEC does not exceed its current limit and the laser’s power and spectrum are stable under operating conditions.
- A power supply capable of 24V DC and 10A to power the TEC controllers.
- Mains power input for 115V AC to the power supply.
- A zero insertion force (ZIF) connector to interface with the laser pins, providing electrical input to the laser diode and laser TEC.
- An internal PCB to condition the pulsed current source to the laser diode, current input connector and voltage monitor BNC output.
In order to successfully deliver the laser control module, the following tasks were required;
- Identify the system’s needs and specify the system components.
- Design an enclosure to house the components.
- Machining of various components-front and rear access plate, base plate and TEC controlled cold plate.
- Create a PCB for the ZIF connector, capable of accepting small form factor spring connectors for electrical connections on laser pins.
- 3D printing of enclosure components to house items and present a finished appearance.
- Assembly of components, soldering of spring connectors to PCB and wiring of internals.
- Thorough testing of the laser module to ensure it operates correctly and meets customer requirements.
The laser module internal assembly, minus the external enclosure, is shown in the figure to the right. The laser package requires a cold plate to ensure the package base is maintained at a constant temperature. Total output from the laser module is approx. 12-15 W into the cold plate. A TEC cooled cold plate was chosen due its small size and ease of use. A TEC controller was included to maintain the cold plate at 25 °C. A second TEC controller was provided to maintain the temperature of the TEC inside the laser. The completed laser module was approx. 8″ x 8″ x 8″ (200 mm x 200 mm x 200 mm).
The laser package has a several 1mm pins that are used to interface with the laser diode, internal TEC and thermistor. A simple PCB was designed to hold spring contacts that were used to create a zero insertion force (ZIF) connection. This ZIF connector was provided above and below the laser package, allowing the user to aim the laser emission to either side of the laser module.
Design and development of a Turnkey laser system
Mid-infrared lasers are used in a variety of applications from infrared countermeasures to chemical sensing. In order to properly operate a bare laser diode, the user would need to be well-versed in several engineering disciplines; electronics (able to provide current and voltage to the laser), heat transfer (able to cool the laser to properly remove waste heat) and laser optics (able to deliver a properly formed laser beam). To provide laser users with a “plug and play” solution, a Turnkey laser system was designed and developed. This system takes care of the operational needs of the laser and lets the customer focus on using the laser without being a laser expert.
The Turnkey laser system consists of a laser head (left) and a controller (right). The laser head was designed in-house and consists of an enclosure, the laser, a custom PCB with internal EEPROM, and a custom heat sink assembly. The controller was provided by a corporate partner, and regulates current and voltage to the laser, maintains temperature control of the laser and heat sink, and provides a convenient user interface.
The Turnkey laser system is a complex product, with a BOM that contains over a hundred parts, not including the internal PCB or controller. From initial design to first production run, this product presented a number of challenges that had to be solved. One of the major challenges that had to be accounted for was the ease of use of the laser system. Whereas a component manufacturer can assume that anyone using their product possess a certain amount of skill in the art, a “plug & play” product requires more careful thought. In the age of the iphone and Amazon, customer expect a modern user interface and a seamless use experience. No detail is small! This includes the little things, like a descriptive manual and quick start guide that gives the user the information they need to operate the laser with confidence.
First units were delivered in 2017 and sales of the Turnkey laser system continue to be strong through 2022, leading to four other variants of wavelength, power and laser type being released for sale.
CAD Samples
“An engineer can do for a dollar what any fool can do for two.”
Arthur Mellen Wellington
The attached files are a handful of the many parts I have designed over the years. But the purpose of an engineer is not just to make pretty pictures, but to create good designs that are both optimized for performance and are cost effective to produce. For the part titled “MEC-100-1503”, the initial customer requests called for a custom heat sink to be machined out of a solid aluminum billet, costing over $350 per part after machining and anodization. Through careful consideration I was able to find a stock heatsink extrusion that met the thermal performance requirements of the project, make minor modifications to that extrusion which made it more cost effective to machine even when using a shop in the US. The end result was a reduction in cost of over 85% for this one part alone and in small quantities (30-50 pcs.), which made the final product easier to source and at better margins than before.