In 2000, Patek Philippe began an Advanced Research program to develop next-generation technologies for watchmaking. These projects resulted in a number of experimental watch movements, many with silicon (“silicium” or “Silinvar”) components, as well as a number of limited-production watches available to the general public.
The first fruit of the Advanced Research project was introduced in 2005. Inside a special Annual Calendar, Ref. 5250 was Cal. 315 S IRM QA LU Si, which contained a silicon escape wheel. This wheel is produced from a microprocessor-style silicon wafer using deep reactive ion etching (DRIE). They found that this wheel, paired with traditional ruby escapement pallets, had the same friction characteristics as lubricated steel but needed no lubrication. This was paired with lubrication-free ceramic ball bearings for the winding rotor and produced in limited numbers.
100 special Annual Calendar watches, Ref. 5250 were produced with this movement, and these included a special “loupe” on the rear sapphire crystal so the silicon escapement can be viewed.
The next year, 2006, Patek introduced another Advanced Research component the “Spiromax” hairspring. One issue with Silicon components is that their physical properties change with temperature. This is especially difficult for a hairspring, which must maintain precisely the same elasticity over time and temperature. Patek solved this issue by coating the silicon hairspring in silicon dioxide. The company also incorporated their patented “Patek Philippe terminal curve” to maintain a flat yet concentric oscillation pattern.
The Spiromax hairspring and silicon escape wheel were brought together in a special Cal. 324 variant. The product of this development was another Annual Calendar, Ref. 5350, this time with 300 pieces produced.
For BaselWorld 2008, Patek Philippe debuted a silicon anchor to create a complete silicon escapement. This new component was dubbed “Pulsomax” and included all three advancements to date in one Cal. 324 movement. This movement features a re-worked escape wheel with 16 teeth instead of the traditional 20 and a new anchor design.
This movement was used in another Annual Calendar, Ref. 5450. Again, it was produced in 300 pieces.
The culmination of the Advanced Research Silinvar project was announced in 2011: The “GyromaxSi” balance. This hourglass-shaped component is crafted of Silinvar with gold weights affixed to the rim. Four adjusters are placed at the rim, two on either side of each weight. Like the other Advanced Research silicon components, the GyromaxSi balance is DIRE etched.
The Pulsomax escapement, Spiromax hairspring, and GyromaxSi balance were brought together with a new name, “Oscillomax”. They were used in a special Cal. 240 variant, this time with a perpetual calendar complication added as well. The resulting watch, Perpetual Calendar Ref. 5550, was produced in 300 pieces.
Although the Advanced Research series is often thought to be synonymous with the progression of Silinvar components outlined above, Patek Philippe has produced other Advanced Research watches as well. These do not fit well within the Silinvar series but are nevertheless important technical developments for the company.
At Basel World in 2012, Patek unveiled their first-ever regulator watch, Annual Calendar Regulator, Ref. 5235G. This watch features an hour hand at 12 00, a central minute hand, and small seconds at 6 00. It also features an annual calendar complication.
This watch does not use the Cal. 240 micro-rotor movement as it might first appear. Rather, it uses an all-new micro-rotor movement, Cal. 31-260 REG QA. Measuring just 5.08 mm thick, the movement contains 313 parts and 29 jewels. Being an Advanced Research product, it includes the Pulsomax escapement, Gyromax balance, and Spiromax hairspring though not the GyromaxSi balance. Unusually, the movement runs 10% faster than Cal. 240 at 3.2 Hz or 23,040 A/h. A display caseback allows a bit of visibility but the “loupe” feature is not present.
Patek Philippe surprised enthusiasts in 2017 by introducing a very-different Advanced Research watch, the Aquanaut Travel Time Ref. 5650. This watch featured no Silinvar components at all, was a sporty Aquanaut model, and lacked exotic complications. Instead, Patek Philippe focused on simplifying the complex mechanism used to set the second time zone in the Cal. 324 movement. This was accomplished using steel springs rather than levers and pivots, and is displayed in an opening in the dial from 7 00 to 11 00.