Beyond the Surface: Innovations in Touch Sensor Technology for Enhanced Human-Machine Interfaces

Semiconductor technology is now deeply embedded in nearly every aspect of modern life, enabling connectivity and automation in our homes, workplaces and urban environments. From simple tasks like activating devices to complex control systems, these advancements rely on both physical touch and wireless interfaces to enhance user experiences. In almost every market area, this technological shift has driven the evolution of smart surfaces—redefining human-machine interface (HMI) by replacing traditional mechanical buttons with seamless, interactive panels. Early touch sensor implementations faced significant limitations, such as poor sensitivity to touch, lack of usability in cold conditions, shrinking application sizes and overall durability concerns. These challenges underscored the need for advanced sensing solutions capable of overcoming these constraints. In addition, traditional mechanical buttons offer only two levels of input—on or off—while the introduction of force sensing unlocks multiple levels of intent, enabling a new dimension of depth and functionality for a variety of use cases.

New HMI sensor technology is enabling high-sensitivity touch detection across various materials. Its robust design makes it ideal for automotive, industrial, consumer and many more applications. Designed to meet automotive and other stringent standards, these new solid-state solutions eliminate mechanical button failures and reduce maintenance costs while enhancing reliability and usability.

Integrated into smart surface applications, Qorvo HMI Force Sensor solutions enable highly sensitive HMI multi-level sensing, XYZ sensing, edge sensing and wake-up sensing with low power consumption and in a small form factor. This paper explores advancements in HMI technology, with a focus on Qorvo’s innovative Force Sensor solutions. It examines how Qorvo’s integrated, solid-state Force Sensors overcome the limitations of traditional HMI designs by enabling highly sensitive, compact and reliable touch interfaces. Key topics include sensor architecture, performance comparisons between competitors and the benefits of miniaturization and low power consumption across various applications.

The Basics of HMI Sensors

At a high level, an effective force-sensing system requires four key components: a sensing element that converts the sensed force into an electrical signal, a low noise amplifier to amplify the signal, an analog-to-digital converter (ADC) to convert the analog signal to a digital output and a microcontroller unit (MCU) to process this signal, as illustrated in below Figure 1.

Figure 1: A comparison between traditional and Qorvo's Force Sensor solution.

Figure 1 compares traditional force-sensing system designs with Qorvo's innovative new solution. Qorvo's all-silicon design integrates both the low noise amplifier and ADC directly within a smaller sensor device – providing applications with an order of magnitude of reduction in form factor, resulting in a smaller footprint than competing designs. Additionally, Qorvo's Sensors come with I2C interface functionality to operate with the customer's host signal-processing MCU.

Qorvo's Force Sensors operate on the same principle as a strain gauge and piezoresistive effect but leverage advanced proprietary technology to deliver significantly higher precision in force measurement. By harnessing silicon's intrinsic piezoresistive properties through advanced semiconductor manufacturing techniques, Qorvo creates sensors with exceptional sensitivity, up to 50 times greater than conventional strain gauges, allowing remarkable precision at the system level. This capability allows accurate monitoring of force. Therefore, Qorvo's Piezoresistive Sensors are ideal for miniature and highly sensitive applications.

All Qorvo’s MEMS Sensors use a full Wheatstone Bridge sensor element configuration. At its core, it meticulously combines electronics and mechanics into one tiny package. See below Figure 2.

Figure 2: Wheatstone Bridge strain gauge method.

This full-Wheatstone Bridge method not only improves sensitivity but also improves temperature compensation and provides a larger output signal. Moreover, the full-bridge configuration offers a linear output directly proportional to the applied force, ensuring greater measurement accuracy. As an example, shown in Figure 3 below, applying pressure to the top of the Qorvo Digital Force Sensor reference design’s aluminum casing produces a strong, linear force count response. This demonstrates the sensor’s ability to deliver consistent and accurate signal output for a given applied force.

Figure 3: Linearity of force output.

Further Analysis of the Qorvo Force Sensor

Qorvo Force Sensors can detect everything from a feather-light finger touch or a gloved hand to varying levels of force, distinguishing between gentle and strong touch. As seen in the brick test in Figure 4 below, the Qorvo Force Sensor is positioned at the bottom of a large brick made of solid ABS material. This test shows how sensitive these force sensors are in a real situation. This high-sensitivity sensor functionality means applications that in the past required many sensors to operate can be done with fewer sensors while achieving the same result.

Figure 4: Sensor test showing high sensitivity of Qorvo Force Sensors.

Further analysis comparing a competing sensor technology to a Qorvo Force Sensor highlights Qorvo’s significantly superior sensitivity and performance. In the following tests, two sensor types were evaluated under identical conditions for a direct comparison. As shown in Figure 5, the Qorvo Sensor demonstrates a force sensitivity six times greater than that of the competing sensor. This comparison displays how Qorvo Sensors are much better suited for applications that require more dense or thicker surfaces.

Figure 5: Comparison between Qorvo and competing force sensors.

Qorvo's enhanced sensitivity enables its sensors to perform exceptionally well across a wide range of surfaces, including harder and thicker materials like aluminum or stainless steel, where competing sensors often struggle to detect applied forces effectively.

Figure 6: Poison ratio for various adhesive and touch surfaces used in force sensor applications.

Beyond hard or thick materials, Qorvo Sensors are also well-suited for seamless or pliable surfaces. For example, conventional toothbrushes often use dome-type switches that can develop surface cracks over time and are vulnerable to moisture ingress due to environmental exposure. In contrast, Qorvo’s Sensors eliminate the need for mechanical gaps or moving parts, reducing the risk of wear, cracks and moisture-related failures, making them ideal for sealed, durable product designs.

Small Size and Low Power Consumption

As noted above, Qorvo Force Sensors feature a compact form factor. Unlike competing solutions, Qorvo provides a highly integrated solution inside a small package using a proprietary packaging technique. Offering a uniquely efficient and integrated design. Using silicon to build a fully integrated module not only addresses the small size requirements for customers, it also has the added benefits of lowering the overall power consumption of the sensor device. Thereby providing customers with lower power consumption for their overall systems. Operating at single digit microamp current levels, Qorvo's Sensor consumes less power than the system's overall leakage current, making it a viable replacement for traditional mechanical power switches.

A Final Word

Qorvo’s innovative HMI Force Sensor solutions deliver a unique combination of precision, durability, compact size and low power consumption—addressing the key challenges faced by traditional force-sensing technologies. By integrating advanced piezoresistive sensing with the full-Wheatstone Bridge architecture and on-chip amplification and conversion, Qorvo enables highly sensitive, reliable and space-efficient force detection across a wide range of materials and environments. Whether in sleek consumer devices or rugged industrial systems, Qorvo is redefining human-machine interaction through smarter, more responsive and more resilient sensor technology. As a leader in HMI sensor technology, Qorvo is committed to delivering industry-leading quality, with its sensors fully qualified to meet the rigorous AEC-Q100 automotive standard. Our solutions perform reliably even in extreme temperatures and high-humidity environments.

Additionally, you can find more interesting collateral on this subject by visiting our Qorvo Design Hub for a rich assortment of videos, technical articles, white papers, tools and more.

For more information on this and other Qorvo automotive design solutions, 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 Sensor Fusion applications. 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: Julius Tsai (Director, MEMS & Solutions), Omar Leung (Director, Customer Solutions), Magnus Ahlstedt (Director of Product Marketing) 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.