The Hardcore Tech of MEMS Force-Tactile Sensors: Silicon Strain Gauges and Glass Micro-Melt Bonding

2026-10-12

The vast majority of conventional six-axis force sensors are built with metal foil strain gauges bonded to an elastic element using adhesive. After long-term storage and use, the adhesive bonding process is prone to aging and loosening — a problem that has remained unsolved for decades. FocusOneMicro chose a more challenging yet promising path: MEMS silicon strain gauges + glass micro-melt bonding. FocusOneMicro’s core technologies:

Technology 1 · Sensing:silicon-based strain gauges — replacing metal foil strain gauges with MEMS silicon strain gauges as the sensing element.
Technology 2 · Manufacturing:glass micro-melt bonding — no adhesive in the bonding layer; strain gauges are sintered onto the elastic element by heating glass powder.

01 The Pain Points of Conventional Metal Foil Strain Gauges

Metal foil strain gauges are bonded to the elastic beams with adhesive. The adhesive layer is prone to aging and creep. Over time, micro-movement occurs, causing significant zero drift and a severe degradation of sensor accuracy.

Mounting is also a problem. Metal foil strain gauges are mostly mounted by hand, which is highly dependent on the worker’s skill. Sidewall beam bonding in particular is easily misaligned, skewing the sensor’s overall output. This process is hard to automate, slow to mass-produce, difficult to keep consistent, and costly to scale down.

Conventional metal foil strain gauges rely heavily on manual workmanship

Core Technology 1: Silicon-Based Strain Gauges

Silicon-based strain gauges are fabricated using the piezoresistive effect, with sensitivity 50–100× that of conventional metal foil. Under the same deformation, they produce a much larger signal, and they are less likely to lose elasticity under overload. FocusOneMicro turned this material property into a mass-producible strain gauge, launching MEMS silicon strain gauge force-tactile sensors.

Silicon-Based Strain Gauges · Sensing Layer
100× sensitivity vs. conventional metal foil strain gauges	1/40 the minimum area vs. conventional metal foil strain gauges	~1/30 the power consumption at the same excitation voltage
Area and sensitivity figures are comparisons with metal foil strain gauges of the same specification; power is calculated as P = V²/R

MEMS silicon strain gauges come from wafers fabricated by photolithography in semiconductor fabs

Compared with metal foil strain gauges, it offers six advantages:

01	High quality, high reliability	The glass micro-melt bonding process sinters the strain gauges onto the elastic element at high temperature, forming a dense inorganic glass structure. Firmness and reliability are significantly improved, long-term displacement is minimized, and the sensor’s zero point and accuracy remain more stable.
02	Small size	The area can be under 0.3 mm², while the minimum area of conventional metal foil strain gauges is typically over 12 mm².
03	Low power consumption	Silicon strain gauges can achieve 10 kΩ resistance, far higher than the 300–400 Ω of metal foil. Under the same excitation voltage, current and power consumption are greatly reduced, benefiting multi-axis simultaneous powering and high-density integration.
04	High sensitivity	Under the same deformation, the output signal of a silicon strain gauge is significantly higher than that of a metal foil strain gauge, with higher SNR and stronger electromagnetic interference immunity. Stable and reliable force signals can be obtained without thousand-fold amplification circuits.
05	Good linearity	Through system calibration and temperature compensation, stable linear output can be maintained across the full measurement range.
06	Suited for mass production	The glass micro-melt bonding process better fits industrial mass production, with better consistency, substantially reduced calibration workload, and significant cost advantage.

Core Technology 2: Glass Micro-Melt Bonding

Glass micro-melt bonding heats glass powder at high temperature to sinter the silicon strain gauges onto the elastic element, directly replacing adhesive bonding. It fundamentally solves the poor long-term stability caused by adhesive aging and creep, as well as the poor consistency caused by manual mounting.

A force sensor fabricated with the glass micro-melt bonding process

Glass Micro-Melt · Manufacturing Layer
Zero adhesive in the bonding step	Glass interface, unlike adhesive bonding	Batch-consistent process — consistency independent of manual mounting

From MEMS silicon strain gauges, to glass micro-melt sintering onto the elastic element, to the final force sensor taking shape

The value delivered by glass micro-melt bonding can be summed up in three points:

Firm bonding, excellent long-term stability
No organic adhesive layer — no aging, no creep
Process-guaranteed consistency, independent of manual mounting

04 Comparison of Technology Routes

There are five common force-sensing routes. Placed side by side on the same set of dimensions, the differences are clear at a glance:

Five force-sensing routes compared across five dimensions: stability, stiffness, dynamic characteristics, SNR, and cost advantage

MEMS silicon strain gauge type	Silicon strain gauges with glass micro-melt bonding. Stability is guaranteed by glass sintering; stiffness comes from the combination of silicon and the metal elastic element; SNR and dynamic response benefit from the high gauge factor; cost is amortized through wafer-scale mass production. (FocusOneMicro)
Metal foil strain gauge type	Nothing stands out, nothing fails badly: accuracy is stable but depends on manual mounting; stiffness and SNR are limited by the adhesive layer and size; mass-production efficiency is low; cost rises with labor.
Capacitive type	Good structural stiffness and high resolution, but the tiny capacitance changes are highly susceptible to environmental interference; shielding and calibration costs are high, and long-term stability depends on the stability of the dielectric medium.
Optical type	High sensitivity and precision, but requires light source, optical path, and image processing; structural stiffness and interference immunity are limited by the optical path; high demands on machining and alignment precision; the most expensive.
Piezoelectric type	Fastest dynamic response — suitable only for dynamic measurement; static force decays over time; requires high-impedance circuitry; poor SNR and long-term stability; structural stiffness limited by crystal size.

05 Conclusion

MEMS silicon strain gauges enable miniaturized, high-sensitivity sensing, while glass micro-melt bonding solves manufacturingconsistency and reliability — these two engineering challenges each now have their own solution. It is batch-delivery consistency that is the precondition for high precision to truly land in practice.