Manufacturing Innovative Sensors through Customized Process Technology

Measure Temperature, Velocity and Humidity without Crowding the Footprint—or Breaking the Bank

Instrumems’ 3D nanowire sensors are smaller, less expensive, faster, and more reliable than conventional environmental sensors. Over the past two decades, sensors have become integral to almost every electronic application. From aerospace, agricultural production, and natural gas monitoring to wearables that help us to achieve our fitness goals or manage a chronic condition, the demand for new sensor technology is surging.

Driven by the need for connected applications that provide information on real-time conditions, and supported by improvements in data collection, cloud storage and wireless connectivity, sensors provide the essential information on which we’ve come to rely.

Q: Which Industries Depend on Sensors?

sensor for robotic vacuum
Robotic Vacuum
sensor for medical ventilator
Sensors for Medical Ventilator

A. Biomedical devices, such as lab-on-chip, ventilators, inhalers, and nebulizers, require high accuracy, low cost, and optional disposability or biodegradability.

A: Smart home devices, such as robotic vacuum cleaners and air purifiers, call for low power consumption, low cost, and seamless connectivity.

A: Industrial applications, such as event-detection systems and high-volume low-cost gas boilers, demand high accuracy and rapid response times.

Smart control panel household gas boiler closeup 3d
Smart control panel household gas boiler closeup 3d

A: Instrumems: MEMS-Based Nanowire Sensors
The Instrumems sensor represents the first major leap forward in flow measurement techniques in the past twenty-five years. Based on a platinum nanowire sensing filament suspended between two supporting electrodes, the Instrumems sensor is approximately 1/75th of a human hair. Providing a small thermal mass of nanowires that enables measurement at high frequencies from 10kHz to 100kHz, the Instrumems sensor sets a new standard for reliability, low cost, and high-frequency measurement response.

Manufacturing Sensors

Instrumems’ sensors are manufactured using Rogue Valley Microdevices’ customer-specific MEMS-based process, which yields devices that are smaller (sub-2mm x 2mm), faster, more accurate, and lower power than conventional sensors. These attributes allow Instrumems’ devices to outperform traditional temperature, velocity and humidity sensors operating in liquid and gaseous flows.

Platinum Nanowire Sensing Filament

The Instrumems sensor represents the first major leap forward in flow measurement techniques in the past twenty-five years. Based on a platinum nanowire sensing filament suspended between two supporting electrodes, the Instrumems sensor is approximately 1/75th of a human hair. Providing a small thermal mass of nanowires that enables measurement at high frequencies from 10kHz to 100kHz, the Instrumems sensor sets a new standard for reliability, low cost, and high-frequency measurement response.

Customer-Specific MEMS-Based Process

Instrumems’ sensors are manufactured using Rogue Valley Microdevices’ customer-specific MEMS-based process, which yields devices that are smaller (sub-2mm x 2mm), faster, more accurate, and lower power than conventional sensors. These attributes allow Instrumems’ devices to outperform traditional temperature, velocity, and humidity sensors operating in liquid and gaseous flows.

nanowire filaments
Instrumems uses nanowire filaments 1/75th of a human hair

Advantages of Instrumems’ Sensors

  • Temperature: With a frequency response of up to 10kHz and accuracy of 0.1ºC, Instrumems’ temperature sensor is the fastest and most accurate sensor available.
  • Velocity: Revolutionizing conventional hot-wire anemometry with a sensing element order of magnitude smaller, Instrumems’ velocity sensor allows flow measurement from microfluidics to airplanes. The sensors also deliver a frequency response of 250kHz — 100x faster than conventional velocity sensors. This high-frequency response results in new information, e.g., flow direction and fluctuations level, which can allow real-time control via flow.
  • Humidity: By leveraging the medium’s thermal conductivity, Instrumems patented a new technique to measure humidity — delivering a frequency response of up to 100kHz. At that level of performance, Instrumems’ sensors provide an alternative to slower, low-cost condensation-prone capacitance sensors, making them ideal replacements for high-end laser sensors.

Wafer Techniques Used

3D nanowire sensors
Instrumems develops unique 3D nanowire sensors that measure temperature, velocity, and humidity.
  1. Photolithography–a stepper projects images of the hundreds of nanowires—which measure just under 2 µ wide—onto a silicon wafer. As this technique isn’t typically performed on wires under 5 µ wide, it’s a remarkable achievement that allows the sensing element to have a very low thermal mass, thereby producing a high-frequency response.
  2. Etching– removes materials from wafers. While semiconductors are typically dry-etched, Rogue Valley Microdevices used a wet etch, a superior process for creating precise patterns on a wafer, to create the 3D elements of the sensors on both sides of a silicon wafer. The precision of the process forms the frame and support for the wires.
  3. Metal deposition– overlays a film on a device. Once the devices have been patterned on the wafer, an ultra-thin metal film forms the platinum wires. The platinum wire is stabilized by support arms but is suspended while the 3D silicon features keep the device intact.

“Rogue Valley Microdevices typically develops a fabrication process for a new sensor after the device is designed. Working with Instrumems, however, gave us the opportunity to both codesign and manufacture the sensor. That early access has allowed us to partner with them every step of the way, to better overcome a variety of engineering challenges. The end result is a new type of 3D sensor that meets the unique requirements of temperature, velocity and humidity sensing.”
Jessica Gomez, Founder & CEO, Rogue Valley Microdevices

Solving Sensor Manufacturing Challenges

To reach pilot production of the Instrumems sensor, Rogue Valley Microdevices overcame three major engineering issues:

  1. Keep the platinum nanowire from breaking, during and after production
  2. Pattern the wafer using a standard 2D semiconductor process on a 3D plane
  3. Release the individual devices from the wafer without breaking the fragile nanowires

To support the wires, Rogue Valley Microdevices designed a 3D sensor—a form factor not typically used in a MEMS device, but crucial to commercializing the new sensor. Ultimately, there emerged a series of “batch” techniques that produced sensors in higher volume (up to 500 per wafer instead of one at a time) and lower cost than previously possible.

Solutions for Batch-Production Nanowire Sensors

Several years into pilot production, the Instrumems sensors are now successfully fabricated with tight process control to repeatedly batch-produce the nanowires. Next, the process will be refined and revised for volume production, expected in 2021.

“Leveraging years of R&D at Princeton University, we worked with Rogue Valley Microdevices to pioneer a commercial fabrication process that uses etching and other semiconductor manufacturing techniques to batch-produce our sensing technology under tight process control. With highly skilled engineers and out-of-the-box thinking, Rogue Valley Microdevices has both helped us articulate our needs — and realize them through fabrication.”
Gilad Arwatz, Ph.D., Founder & CEO Instrumems Inc

Sales/Customer Support

Are you interested in manufacturing innovative sensors through customized process technology?

Contact Rogue Valley Microdevices today at our Corporate Headquarters:
Phone: 541-774-1900
Fax: 541-774-1904
Email: sales(at)roguevalleymicro.com

Founded in 2003 and conveniently located in the Rogue Valley region of Southern Oregon, approximately halfway between San Jose, Calif. and Portland, Ore., Rogue Valley Microdevices is a full-service precision MEMS foundry that combines state-of-the-art process modules with market-specific expertise. Specializing in microfluidics, smart sensing devices, and lab-on-a-chip, we partner with customers from early R&D through pilot production.

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