31 may comprise silicon, germanium (Ge), chalcogenide glass, gallium arsenide (GaAs), zinc sulfide (ZnS), zinc selenide (ZnSe) or a combination thereof, but the present disclosure is not limited thereto. In addition, in one embodiment of the present disclosure, the reflective index of the optical lens 31 may be greater than 2.0.

In the present disclosure, when the material of the optical lens 31 and the material of the upper substrate 3′ are the same, the upper substrate 3′ may be patterned through a lithography process to form the optical lens 31 on the upper substrate 3′. Alternatively, when the material of the optical lens 31 and the material of the upper substrate 3′ are the same or different, the material of the optical lens 31 may be first deposited on the upper substrate 3′, followed by patterning through a lithography process to form the optical lens 31 on the upper substrate 3′. By combining the optical lens 31 and the upper substrate 3′ or integrating the optical lens 31 and the upper substrate 3′, no additional optical lenses are required, which can simplify the manufacturing process or save costs.

Next, as shown in FIG. 3B, the lower substrate 1′ and the upper substrate 3′ are assembled through a bonding process. More specifically, by performing the bonding process on the first bonding units 11 of the lower substrate 1′ and the second bonding units 32 of the upper substrate 3′, the upper substrate 3′ and the lower substrate 1′ are assembled to form a sealed space SP, wherein the sensing units S and the optical lens 31 are overlapped in the normal direction Z of the sensing device. In the present disclosure, the bonding process may include thermo-compression bonding, eutectic bonding, laser welding, other suitable processes or a combination thereof.

Then, the lower substrate 1′ and the upper substrate 3′ are cut into appropriate sizes to form the sensing device. Hence, as shown in FIG. 3C, the sensing device may comprise: a first substrate 1; a plurality of sensing units S disposed on the first substrate 1 and used for sensing light with wavelengths within a wavelength range; and a second substrate 3 disposed opposite to the first substrate 1 and assembled to the first substrate 1, wherein the second substrate 3 has an overlapping area R1 overlapping with the sensing units S in a normal direction Z of the first substrate 1, wherein the second substrate 3 has an optical lens 31 in the overlapping area R1, the optical lens 31 comprises a plurality of micro-structures 311, and a pitch P between the micro-structures 311 is less than or equal to a maximum wavelength value of the wavelength range.

In this disclosure, the material of the first substrate 1 is as described above, the material of the second substrate 3 may be referred to the material of the upper substrate 3′, the sensing units S are as shown in FIG. 1, the material of the optical lens 31 is as described above, and these are not described again. In the present disclosure, the sensing units S may sense light in the infrared wavelength range. For example, the sensing units S may sense light in the wavelength range between 8 μm and 20 μm. The optical lens 31 may converge or diverge light and may be used to improve the sensing effect of the sensing units S.

As shown in FIG. 3C, in one embodiment of the present disclosure, the second substrate 3 has a recess 33, and the optical lens 31 may be disposed in the recess 33. In one embodiment of the present disclosure, a distance D1 between the optical lens 31 and the sensing units S is between 150 μm to 250 μm in the normal direction Z of the first substrate 1. In the present disclosure, the distance D1 is defined as the distance between the surface of the optical lens 31 and the surface of the passivation layer 29 of the sensing unit S (for example, the fourth passivation layer 29 of the sensor S1 in FIG. 2). In one embodiment of the present disclosure, the second substrate 3 may comprise a first surface 3a and a second surface 3b opposite to the first surface 3a, wherein the first surface 3a is closer to the first substrate 1 than the second surface 3b, and the optical lens 31 may be disposed on the first surface 3a of the second substrate 3.

In the present disclosure, as shown in FIG. 3C, the sensing device may further comprise: first bonding units 11 disposed on the first substrate 1, wherein the sensing units S are disposed between the first bonding units 11; and second bonding units 32 disposed on the second substrate 3, wherein the optical lens 31 is disposed between the second bonding units 32. The first substrate 1 and the second substrate 3 may be assembled through the first bonding units 11 and the second bonding units 32 to form a sealed space SP. The sealed space SP may be a vacuum or close to a vacuum, which can reduce the interference of other external environment factors (such as moisture, air, etc.) on the sensing signals. In addition, the sensing device may further comprise a pad 12 disposed on the first substrate 1, wherein the pad 12 is disposed adjacent to the sensing array Ar and is electrically connected to the sensing array Ar. The sensing array Ar may be electrically connected to external components (such as the drivers Dr1, Dr2 or the electronic component E shown in FIG. 1) through the pad 12 to transmit or receive signals.

FIG. 4 is a schematic view of a sensing device according to one embodiment of the present disclosure. The sensing device in FIG. 4 is similar to that shown in FIG. 3C, except for the following differences.

In one embodiment of the present disclosure, as shown in FIG. 4, the sensing device may further comprise an optical film 4 disposed on the second substrate 3. More specifically, the optical film 4 may be disposed on a side of the second substrate 3 away from the optical lens 31. For example, the optical film 4 may be disposed on the second surface 3b of the second substrate 3, but the present disclosure is not limited thereto. In other embodiments of the present disclosure, even not shown in the figure, the optical film 4 may be disposed on the optical lens 31. For example, the optical film 4 may be disposed on the first surface 3a of the second substrate 3 and the surface 31a of the optical lens 31. In other embodiments of the present disclosure, even not shown in the figure, the optical film 4 may be disposed on the first surface 3a and the second surface 3b of the second substrate 3. The optical film 4 may be used to reduce the reflection of incident light and/or block light in unwanted wavelength ranges to increase the transmittance of light in a specified wavelength range, thereby improving the sensing effect. In the present disclosure, the specified wavelength range may be, for example, between 8 μm and 20 μm or between 8 μm and 14 μm, but the present disclosure is not limited thereto. In one embodiment of the present disclosure, the optical film