Beyond Touch: Enabling Intent with Qorvo’s MEMS Force Sensors

The commercialization of solid-state touch sensor technology has driven widespread adoption across Human-Machine Interface (HMI) applications. These sensors enable sleek, seamless designs that enhance both product aesthetics and system-level performance. By enabling design engineers to create sensor functionality in fully enclosed surfaces, they help prevent dirt and moisture ingress, making devices easier to clean and maintain—benefits now familiar to anyone using modern smart devices.

This technical article examines the evolving landscape of HMI sensor technologies, comparing capacitive and resistive (force-based) approaches. It highlights the performance trade-offs, design considerations and environmental factors that influence sensor selection. Special emphasis is placed on the capabilities of next-generation force sensors, like enhanced sensitivity, material compatibility and resilience in challenging conditions. Through this comparison, the article outlines how advancements in force-sensing technologies, such as Qorvo's, are shaping the future of intuitive, reliable, and robust touch interfaces.

A Look Beyond the Traditional Touch Approach

Today, thanks to smartphones, we are familiar with capacitive touch technology, which has become widely adopted across numerous applications beyond our phones. While this solid-state sensing technology offers convenience, it also comes with a few drawbacks, including the potential for unintentional activation from accidental touches or swipes. For example, we are all very familiar with making an unintended phone call because our capacitive touch screen was accidentally swiped while inside our pocket or purse. While detecting the proximity or light touch of a finger may suffice in some capacitive touch sensor scenarios, it fails to replicate the haptic sensation and information conveyed by the intentional press of a mechanical button. Therefore, it can lead to false triggering touch events.

Furthermore, capacitive touch systems only work well with certain materials like glass or plastic, which limit design flexibility. In contrast, resistive force sensors can function through a wider range of materials, including metal, wood and plastic, offering more versatility for product design. Moreover, capacitive touch performance is also more susceptible to environmental factors like humidity and temperature, making it less reliable in certain conditions. These limitations can restrict the practical use of capacitive touch sensors in many applications. Table 1 below compares the features of capacitive touch sensors and Qorvo’s MEMS Force Sensors, highlighting their key differences and showcasing the advantages of using Qorvo’s MEMS technology in various applications.

Table 1: Comparison between capacitive touch sensor and Qorvo MEMS Force Sensor.

Capacitive and resistive force touch sensors each offer distinct advantages, and understanding their differences is key to making the right choice for an application. While cost may be a consideration, the decision should ultimately be guided by the specific user environment and desired experience. It's not just about how each sensor type functions, but about selecting the one that best aligns with the end-user requirements—whether that means precision, durability, material compatibility or resistance to environmental factors.

Comparing Market Available Force Sensors

Table 2 provides a comparison of Qorvo’s MEMS Sensors against other force sensor technologies currently available on the market. Focusing on key parameters such as sensitivity, compact size, durability and linearity, Qorvo’s Sensors clearly stand out. These advantages translate into a more reliable, responsive and high-quality user experience—giving product designers the performance edge needed to differentiate their solutions.

Table 2: Comparing between force sensor technologies.

Moreover, Qorvo Piezo-Resistive MEMS Force Sensors demonstrate excellent durability, making them well-suited for demanding environments. Their robust construction ensures reliable performance over time, even in challenging conditions. This durability contributes to the longevity of the devices in which they are integrated.

Finally, the superior linearity of piezo-resistive MEMS force sensors simplifies the calibration process, ensuring that users can achieve accurate measurements with minimal effort. This linear response enhances the reliability of the sensor's output, providing consistent and precise feedback during user interactions.

Qorvo's MEMS-based Force Sensors

Next-generation force sensor technologies are now entering a market once dominated by capacitive touch sensors, offering significant improvements in usability and reliability. Unlike capacitive solutions, these advanced resistive force sensors accurately detect true user intent and provide the interruption needed to create mechanical-like haptic feedback to confirm that a button has been pressed. This approach greatly reduces the risk of false touches and enhances precision and user experience across a wide range of applications.

Qorvo's Force Sensors are truly unique yet simple in their working principle. They are based on the same principle as the strain gauge. The Qorvo design uses the full-bridge Wheatstone circuit design, as shown in Figure 1 below. Using this design and exploiting the intrinsic properties of silicon—the base material for worldwide semiconductor manufacturing—Qorvo has enabled the creation of highly sensitive piezo-resistive elements. The solution is a proprietary process that leverages advanced semiconductor design along with packaging and manufacturing techniques. Additionally, this small package houses both the Wheatstone bridge as well as a low noise amplifier (LNA) and analog-to-digital converter (ADC). Through the efficient use of chip real estate, Qorvo has integrated digital content within the same footprint as the analog sensor, allowing for the full integration of the Analog Front End, all within a footprint of around 1 mm².

Figure 1: Wheatstone Bridge and Qorvo Force Sensor

This proprietary design has allowed Qorvo to achieve an extremely small device form factor in a Wafer Level Chip Size Package (WLCSP) while maintaining unparalleled sensitivity.

Moreover, the integrated sensor design makes it practically immune to the impact of electromagnetic interference (EMI) from surrounding applications or environmental sources. As a result, engineers can focus their EMI mitigation efforts on other system components with confidence that the Qorvo Force Sensor is inherently resistant to such interference.

Deeper Dive into Force-Sensor Sensitivity

A key feature of the Qorvo Piezo-Resistive MEMS-based Force Sensors is their exceptional sensitivity, enabling precise detection of even the smallest changes in force. This capability is particularly beneficial in applications where accuracy is paramount, enabling reliable performance across a variety of use cases. The Qorvo Sensor has a high force count compared to competitors with the same strain gauge test parameters applied. This high sensitivity also allows for integration into product designs with strict material or design constraints. This means these sensors can perform effectively in scenarios where the transducer is tiny or where the material used has a high modulus of elasticity, such as metals, which typically produce small mechanical signals.

Small Form-Factor and High Versatility

In addition to their sensitivity, these Qorvo MEMS Sensors excel in both dynamic and static measurements. This versatility makes them suitable for a wide range of applications, from monitoring continuous pressure to capturing transient forces. Force sensor interactions can typically be considered quasi-static, where most interactions occur at relatively low speeds. In some cases, a persistent load, such as a "long press," might be required to trigger specific functions. For this specific use case, there is no viable alternative to the piezo-resistive implementation, as it ensures that user interactions are consistently recognized, enhancing the overall user experience.

Another significant advantage of using Qorvo’s Piezo-Resistive MEMS Force Sensors is their compact size. Their small form factor allows for seamless integration into space-constrained designs, making them ideal for modern electronic devices where minimizing footprint is essential. This characteristic is particularly valuable in applications such as wearables and portable electronics, where every millimeter counts.

With the market introduction of solid-state Micro-Electro-Mechanical System (MEMS) Force Sensors, Qorvo offers a solution that addresses these challenges seen by capacitive touch technology and brings true intent to these HMI applications. By operating in the mechanical domain, these force sensors restore the value of the mechanical button, providing intent and confirmation feedback while still allowing for sleek and seamless design. Whether used independently or in conjunction with capacitive touch, Qorvo's Force Sensors provide a complementary tool for HMI designers, opening up new possibilities in design and feature sets.

Conclusion

As the demands for HMI applications continue to grow, the limitations of traditional capacitive touch sensors have become increasingly apparent. Qorvo’s Piezo-Resistive MEMS Force Sensors offer a compelling alternative—delivering superior sensitivity, durability, and material versatility in a compact, low-power and small form factor. With integrated features such as a full Wheatstone Bridge, LNA and ADC, these sensors are engineered for precision and reliability even in harsh or space-constrained environments. By reintroducing intentional feedback into modern device designs, Qorvo is bridging the gap between mechanical responsiveness and sleek, solid-state interfaces. Whether used alone or alongside capacitive technology, Qorvo’s Force Sensors empower engineers to create more intuitive, robust, and differentiated HMI solutions for the next generation of smart devices.

Additionally, you can find more information on this subject by visiting our Qorvo Design Hub for a rich assortment of videos, technical articles, white papers, tools, and more. For technical support, please visit Qorvo.com or reach out to Technical Support.

About the Authors

Our authors bring a wealth of technical expertise in developing and optimizing Human Machine Interface (HMI) solutions. With a deep understanding of customer needs and industry trends, they collaborate closely with our design teams to drive innovation and deliver cutting-edge solutions that support industry-leading products.

Thank you to our main contributors of this article; Magnus Ahlstedt (Director, Product Marketing), Julius Tsai (Director, MEMS & Solutions) and David Schnaufer (Corporate, Technical Marketing Manager) for their contributions to this blog post, ensuring our readers stay informed with expert knowledge and industry trends.